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WO2012072855A1 - Calibrating method and apparatus - Google Patents

Calibrating method and apparatus Download PDF

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Publication number
WO2012072855A1
WO2012072855A1 PCT/FI2010/050986 FI2010050986W WO2012072855A1 WO 2012072855 A1 WO2012072855 A1 WO 2012072855A1 FI 2010050986 W FI2010050986 W FI 2010050986W WO 2012072855 A1 WO2012072855 A1 WO 2012072855A1
Authority
WO
WIPO (PCT)
Prior art keywords
image
calibration
brightness
ambient
data
Prior art date
Application number
PCT/FI2010/050986
Other languages
French (fr)
Inventor
Max Lindfors
Original Assignee
Nokia Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nokia Corporation filed Critical Nokia Corporation
Priority to PCT/FI2010/050986 priority Critical patent/WO2012072855A1/en
Publication of WO2012072855A1 publication Critical patent/WO2012072855A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46Colour picture communication systems
    • H04N1/56Processing of colour picture signals
    • H04N1/60Colour correction or control
    • H04N1/603Colour correction or control controlled by characteristics of the picture signal generator or the picture reproducer
    • H04N1/6052Matching two or more picture signal generators or two or more picture reproducers
    • H04N1/6055Matching two or more picture signal generators or two or more picture reproducers using test pattern analysis
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/80Camera processing pipelines; Components thereof
    • H04N23/84Camera processing pipelines; Components thereof for processing colour signals
    • H04N23/85Camera processing pipelines; Components thereof for processing colour signals for matrixing
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/80Camera processing pipelines; Components thereof
    • H04N23/84Camera processing pipelines; Components thereof for processing colour signals
    • H04N23/88Camera processing pipelines; Components thereof for processing colour signals for colour balance, e.g. white-balance circuits or colour temperature control

Definitions

  • telemedicine refers to the practice of medicine over a distance.
  • diagnostics, treatment decisions and recommendations are based on images, data, documents and/or other information transmitted through telecommunication systems.
  • telemedicine there is a growing interest in mobile phones, both for image acquisition and for image viewing, because of the usability and economic efficiency of mobile phones. By using these advances in mobile telemedicine, it is possible to take an image with a mobile phone and view the image with another mobile phone by a remotely located physician or another specialist.
  • a physician or a specialist practicing telemedicine is responsible for the appropriate quality of his services. Medical opinions and recommendations can be given and medical decisions made if the quality of image/s, data or other information received is of sufficiently high standard and the systems used are adequately operational.
  • the contrasts of patient images are relevant in telemedicine systems, but the contrast is not correctly reproduced by either conventional or mobile imaging systems.
  • a method for receiving image data in an apparatus determining ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieving a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieving an ambient correcting value corresponding to the ambient illumination data; and applying the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
  • a calibration correction matrix and ambient correcting value are applied to correct original image data so that image data may be displayed at the second location as it was originally seen by the camera at the first location.
  • the calibration correction matrix is produced in a calibration process, wherein the first and second apparatus are calibrated to each other and the ambient correcting value for ambient illumination data of the second location is produced by a calibration process, wherein the second apparatus is calibrated at the second location or at a corresponding condition, by a first apparatus.
  • an apparatus comprising a processor and a memory including computer program code, the memory and the computer program code being configured to, with the processor, cause the apparatus to receive image data; determine ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
  • a system comprising at least an image displaying device and an image capturing device, both comprising a processor and a memory including computer program code, the memory and the computer program code configured to, with the at least one processor, cause the system to: transmit image data from the image capturing device; receive image data in the image displaying device; determine ambient illumination condition of the image displaying device for obtaining ambient illumination data by the image displaying device; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device by the image displaying device; and retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
  • an apparatus comprising means for receiving image data; means for determining ambient illumination condition of the apparatus for obtaining ambient illumination data retrieving ambient illumination data; means for retrieving a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; means for retrieving an ambient correcting value corresponding to the ambient illumination data; and means for applying the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
  • a computer program product stored on a storage medium comprising a computer program code configured to, with at least one processor, cause an apparatus to receive image data, determine ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
  • Fig. 1 shows a flow chart of image data correcting process according to an example embodiment
  • Fig. 2 shows an apparatus arranged to receive and view images according to an example embodiment
  • Fig. 3 shows a flow chart of a calibration process of two mobile apparatuses according to an example embodiment
  • Fig. 4 shows a calibration process of two apparatuses according to an example embodiment
  • Fig. 5 shows an operation of an apparatus according to an example embodiment
  • Fig. 6 shows a flow chart of an operation of an image correcting process according to an example embodiment.
  • a device capturing and transmitting an image data and a device receiving and displaying corrected image data may not have to be identical or technically substantially similar. However, if these devices are identical or technically substantially similar, for example, the same model, or these devices behave identically, it might be beneficial to users of devices for displaying reproduced corrected images.
  • Figure 1 shows a flow chart of an image correcting process according to an example embodiment.
  • an apparatus that is, for example, an image displaying device such as a mobile communication device, mobile phone, laptop, camera, personal digital assistant (PDA), tablet or other means to receive image data, to correct the received image data and to display corrected image data.
  • the received image data may be received from an image capturing device that may have captured said image data or may have received said image data from some other device that is substantially technically identical to the image capturing device, for example, the same model.
  • Both devices may comprise a camera or other means capturing image data and a display or other means displaying image data.
  • the devices may have been calibrated to each other.
  • One calibration method suitable to be used in this embodiment is disclosed in connection with figure 3.
  • the devices may not necessarily be calibrated to each other. Instead, it may be sufficient that the devices are calibrated to some other identical device e.g. the same product model or a device that technically behaves substantially identically or a device that is technically similar enough.
  • the calibration may not need to be done device-to-device, but, for example, within a group comprising devices with the same product model. It may be sufficient that any two devices within that group have been calibrated to each other. After calibration image data captured by one device may be reproduced as captured on a display of any other device within that group.
  • the image displaying device receives image data e.g. from the image capturing device.
  • the image displaying device may receive the image data, for example, as email, MMS or other suitable type depending on the selected channel.
  • the image displaying device determines ambient illumination condition of the image displaying device for obtaining ambient illumination data.
  • the image displaying device may determine the ambient illumination condition by an ambient light level information value from an ambient light sensor (ALS) and an ambient light color information value from the camera of the image displaying device, for example from a front-side camera.
  • the image displaying device may store this ambient illumination data relating to ambient illumination condition in a memory.
  • the memory may be any means for storing, for example, any internal memory of the apparatus or an external memory such as a micro secure digital (SD) card or a server.
  • SD micro secure digital
  • the image displaying device retrieves a calibration correction matrix from a memory.
  • the memory may be some other means for storing or the same memory, wherein the data relating to ambient illumination condition is stored.
  • the calibration correction matrix is a calibration profile mathematically defining the relation between red, green and blue (RGB) intensity values and/or brightness of display of the image displaying device and RGB intensity values of the camera of the image capturing device.
  • the calibration correction matrix may comprise one coefficient that is determined during calibration.
  • the coefficient may be used as a multiplier to correct brightness and/or RGB intensity values of the received image data.
  • the calibration correction matrix may also comprise several coefficients, if the image is divided into parts, so that each coefficient acts as a multiplier for one part of the image.
  • the calibration correction matrix comprises a correction coefficient for each pixel of the image data to be corrected. If there is not the calibration correction matrix for the image displaying device in the memory, the user of the image displaying device may be requested to calibrate the image displaying device.
  • the image displaying device retrieves the ambient correcting value from a memory, wherein the ambient correcting value corresponds ambient illumination data of the determined ambient illumination condition of the image displaying device.
  • the ambient correcting value corresponds ambient illumination data of the determined ambient illumination condition of the image displaying device.
  • There may have been stored a plurality of ambient correcting values corresponding to different ambient illumination data of ambient illumination conditions of image viewing in the memory, and these values are stored in connection with ambient calibration values for ambient illumination data of different ambient illumination conditions.
  • the image displaying device may retrieve at least two ambient correcting values that are the closest ones to the ambient illumination data of the ambient illumination condition and interpolate an ambient correcting value that corresponds to the ambient illumination data of the image displaying device.
  • software of the image displaying device may ask the user of the image displaying device to calibrate the image displaying device in current ambient illumination condition if there is no ambient correcting value that corresponds to ambient illumination data of the determined ambient illumination condition in the memory or if interpolating may not be done.
  • the calibration for the current ambient illumination condition may be executed on the devices, so that the image displaying device is being calibrated and the image capturing device is used as a calibrator.
  • the calibration may be performed in the location where image viewing is going to take place with the image displaying device or in condition similar to the ambient illumination condition of the location of the image displaying device.
  • the image displaying device is placed as it will be used for image viewing.
  • the calibration software runs on both devices.
  • the image capturing device is placed to mimic eyes of the user of the image displaying device.
  • the calibration software of the image displaying device provides a calibration image to the display of the image displaying device.
  • the image capturing device captures, without flash, an image of the calibration image and transmits the brightness value of the captured image to the image displaying device.
  • calibration software of the image displaying device is arranged to compare brightness of the calibration image that was actually displayed on the display of the image displaying device against brightness of the image captured by the camera of the image capturing device and stores this offset data as an ambient correcting value.
  • the image displaying device also stores its ALS data and ambient light color information value from the camera, for example, from a front-side camera, of the image displaying device as an ambient illumination data to refer this calibrated ambient correcting value, so that an ambient correcting value corresponding to ambient illumination data of a certain ambient illumination condition may be retrieved.
  • the software of the image displaying device may calculate at least one ambient correcting value for the current ambient illumination data including corrections related to the effect of the ambient light that was detected from the display of the image displaying device.
  • the ambient correcting value for the current ambient illumination data is stored into the memory.
  • both devices transmit their information about brightness values of at least one displayed image and at least one captured image to an external computing device, for example, to a server, that compares brightness values and calculates the ambient correcting value for adjusting brightness value of the received image data and further stores it for later use or transmits it to the image displaying device.
  • the memory is not physically located in the image displaying device, in which case the memory checking is carried out by communicating with an external memory, such as a micro SD card or a server instead of accessing internal memory, and wherein the external memory may comprise a plurality of ambient correcting values for different ambient illuminations for similar devices as the image displaying device and/or for a plurality of different kind of devices.
  • an external memory such as a micro SD card or a server instead of accessing internal memory
  • the external memory may comprise a plurality of ambient correcting values for different ambient illuminations for similar devices as the image displaying device and/or for a plurality of different kind of devices.
  • the ambient correcting value and the calibration correction matrix is applied to the received image data.
  • the software on the image displaying device may form a corrected image data based on the received image data by applying the ambient correcting value and the calibration correction matrix to received image data.
  • the corrected image data is displayed on the display of the image displaying device as an output image, wherein brightness and RGB intensity values are set according to instructions of the calibration correction matrix and the ambient correcting value.
  • the software of the image displaying device may further be arranged to determine ambient illumination condition at intervals during the displaying of the output image, for example, at one- minute intervals. If the ambient illumination condition changes comparing to earlier ambient illumination condition, the software retrieves a new ambient correcting value corresponding to the changed ambient illumination data of the ambient illumination condition from the memory and uses the ambient correcting value in connection with correcting the received image data so that the changed condition, for example, during the viewing is taken into account.
  • FIG. 2 illustrates a simplified structure of an apparatus 200 capable of receiving and correcting image data according to an example embodiment.
  • the apparatus may be, for example, a mobile terminal, a mobile phone, a smart phone, a PDA device, an Internet access device (Internet tablets), a laptop computer, personal computer (PC) or any other data processing device that may comprise means for displaying image data such as a display and means for image capturing such as a camera.
  • the apparatus 200 comprises I/O means (I/O) 202, a central processing unit (CPU) 204, a memory (MEM) 206 and 256, and computer program code 216 residing in the memory 206 for implementing, for example, calibration.
  • I/O I/O
  • CPU central processing unit
  • MEM memory
  • computer program code 216 residing in the memory 206 for implementing, for example, calibration.
  • the memory 206 may comprise a read-only memory (ROM) portion and a rewriteable portion, such as a random access memory (RAM) and FLASH memory.
  • the information used to communicate with different external parties e.g. an image displaying apparatus calibrated with an image displaying apparatus or other identical apparatus that is calibrated with the image displaying apparatus, is transmitted through the I/O means (I/O) 202 to/from the CPU 204.
  • the apparatus 200 may be implemented as a mobile station, so it includes a transceiver Tx/Rx (208), which communicates with the wireless network, typically with a base transceiver station (BTS) through an antenna 210, but also through Bluetooth® with another phone, for example, in connection with calibration process.
  • Tx/Rx 208
  • Ul 212 equipment includes at least a display and a camera, such as a front side camera for determining of ambient illumination data of ambient illumination condition but it may also include a keypad and connecting means, for example, for a separate display, if there is a need to view the reproduced image also on a bigger display.
  • the apparatus 200 may also comprise an ambient light sensor (ALS) 214 for determining of ambient illumination condition.
  • ALS ambient light sensor
  • Figure 3 illustrates a method for calibration process for apparatuses A and B according to another example embodiment, wherein both apparatuses A and B comprise at lease a display and a camera.
  • Calibration software may run on both apparatuses at the same time and the apparatuses may be located in a darkened room.
  • apparatus A is going to be calibrated and apparatus B acts as a calibrator.
  • the calibration software of apparatus A displays a calibration image at the display of apparatus A, and at stage 31 1 , the camera of apparatus B captures an image of the calibration image without flash.
  • apparatus B transmits brightness and/or RGB intensity values of the captured image to apparatus A.
  • the calibration software of apparatus compares brightness and/or RGB intensity values of the calibration image that was actually displayed against the brightness and/or RGB intensity values of the image captured by apparatus B.
  • this data is stored to a memory. This stored data establishes the offset values of brightness and/or RGB intensity values of the display of apparatus A and the camera of apparatus B.
  • Apparatus B is calibrated and apparatus A acts as a calibrator.
  • the calibration software of apparatus B displays a calibration image and at stage 321 apparatus A captures an image of the calibration image on the display of apparatus B without flash.
  • apparatus B transmits brightness and/or RGB intensity values of the displayed image to apparatus A.
  • the calibration software of apparatus A compares the brightness and/or RGB intensity values of image that was actually displayed against a brightness value captured by the camera of apparatus A
  • the calibration of apparatus B with apparatus A may not be necessary (stages 320 to 323) for creating a calibration correction matrix. It may be possible to create a calibration correction matrix on the basis of the calibration of apparatus A with apparatus B.
  • the calibration software on apparatus A creates and stores a calibration correction matrix on the basis of offsets of these brightness and/or RGB intensity values of displayed and captured images. Then apparatus A forms and stores the calibration correction matrix, wherein the matrix mathematically defines the relation between brightness or RGB intensity values of the display and RGB intensity values of camera.
  • This calibration correction value matrix is going to be used in connection with correcting received image data so that received image data may be reproduced on the display of apparatus A as it was originally captured.
  • both apparatuses A and B display at least one calibration image and capture at least one image before any data is transmitted for forming of the calibration correction matrix.
  • both apparatuses A and B transmit brightness or RGB intensity values of displayed and captured images to an external computing device, for example, to a server or some other computer that compares offsets of values and calculates and form the calibration correction matrix and transmits the matrix to apparatus A or stores it for later use.
  • Figure 4 illustrates a calibration process between apparatuses A and B according to an exemplified embodiment, wherein apparatuses A and B are substantially similar from a technical point of view.
  • These apparatuses may communicate with each other by using Bluetooth® or any other means suitable for forming connection between apparatuses A and B.
  • the apparatus A is going to be calibrated and apparatus B is going to be used as a calibrator.
  • Apparatus A displays calibration images at different display brightness settings and a camera 400 of apparatus B captures, without flash, at least one image from said calibration images.
  • apparatus B transmits the brightness and/or RGB intensity values of captured images to apparatus A e.g.
  • apparatus B is going to be calibrated by apparatus A.
  • the calibration software of apparatus B displays a series of calibration images on the display 420 of apparatus B again at different display brightness settings and apparatus A captures images of calibration images of apparatus B by a camera 430 without flash.
  • apparatus A transmits the brightness and/or RGB intensity values of captured images to apparatus B by Bluetooth®.
  • the calibration software of apparatus B compares the values of images that were actually displayed against the captured images. This offset data of values is transmitted to apparatus A e.g. via Bluetooth®.
  • FIG. 5 illustrates an operating situation of an apparatus for viewing received image data according to another example embodiment.
  • a doctor using an apparatus B 510 needs comments about an X-ray 520 from a specialist using an apparatus A 530.
  • Apparatuses B 510 and A 530 are technically substantially identical and they have been calibrated to each other.
  • the doctor captures an image of the X-ray 520 by a camera 540 of his apparatus B 510 and sends image data of the X-ray 520 by a multimedia message to the apparatus A 530 of the specialist.
  • the doctor uses his apparatus B 510 in a good viewing condition that is, for example, in a darkened room, but the specialist is out in bright sunshine when apparatus A 530 receives the image data of X-ray 520. Bright sunshine may decrease viewing conditions. So before viewing the received image of the X-ray 520 the apparatus A 530 determinates ambient illumination condition of apparatus A 530 from an ambient light level value from an ambient light sensor (ALS) 550 and an ambient light color information value from the camera 560 of apparatus A 530 for obtaining ambient illumination data. At next stage, apparatus A 530 retrieves an ambient correcting value corresponding to the ambient illumination data from a memory of apparatus A 530. Further, apparatus A 530 retrieves a calibration correction matrix from the memory of apparatus A 530.
  • ALS ambient light sensor
  • the calibration correction matrix is stored in the memory of apparatus A 530 in connection with the calibration process of apparatuses B 510 and A 530 or the calibration correction matrix is transmitted to apparatus A 530 after a calibration of two other phones that are substantially technically similar to apparatus A 510.
  • the apparatus A 530 uses the ambient correcting value and the calibration correction matrix to correct the received image data.
  • apparatus A 530 is capable of display the corrected image data of X-ray 520 as an output image 570 on the display and the output image 570 is shown as the camera 540 of apparatus B 510 saw it in the ambient illumination condition of apparatus B 510.
  • apparatus A 530 or any other apparatus receiving image data to be displayed is calibrated with some other apparatus than the apparatus that transmits the image data.
  • the apparatus used for calibrating is substantially technically similar to the apparatus 510, for example, the same model.
  • the software of apparatus A 530 may include predetermined threshold values, lux levels, for ambient illumination data of the ambient illumination conditions and may warn the user of apparatus A 530 if he is attempting to display image data in too low or too high ambient illumination conditions or may turn the display off when the ambient illumination data is not within the threshold values.
  • the software determines ambient illumination condition of apparatus A 530 at intervals during the viewing of an image, for example, at one-minute intervals. If ambient illumination condition changes compared to earlier ambient illumination condition of apparatus 510, the software checks if ambient illumination data of the changed ambient illumination condition is still within threshold values and ambient illumination condition is suitable for viewing the image. Thus changed condition, for example, during the viewing may be taken into account. It is also possible to arrange the software to determine ambient illumination condition of apparatus A 530 at intervals, if the ambient illumination data is at first determined to be outside the threshold values and ambient illumination condition is not suitable for displaying the image. In which case, the ambient illumination conditions may be re-determined until condition changes suitable for displaying the image or the ambient illumination conditions may be re-determined at predetermined times, for example, ten times, if condition is not changed suitable for viewing the image before that.
  • Figure 6 shows a method for image data correcting process according to an embodiment.
  • image data is received.
  • ambient illumination condition of an apparatus is determined from an ambient light sensor and from a camera of the apparatus for obtaining ambient illumination data.
  • a calibration correction matrix is retrieved.
  • an ambient correcting value for the ambient illumination data is retrieved.
  • the calibration correction matrix and the ambient correction value is applied to received image data.
  • a terminal device may comprise circuitry and electronics for handling, receiving and transmitting data, computer program code in a memory, and a processor that, when running the computer program code, causes the terminal device to carry out the features of an embodiment.

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Abstract

Various embodiments relate to a method, apparatus, system, and a computer program product for image correction. In the method image data is received in an apparatus. Ambient illumination condition of the apparatus is determined for obtaining ambient illumination data. A calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device and an ambient correcting value corresponding to the ambient illumination data are retrieved. The calibration correction matrix and the ambient correcting value are applied to the received image data so that corrected image data is obtained.

Description

Calibrating method and apparatus Background
The term telemedicine refers to the practice of medicine over a distance. In telemedicine, diagnostics, treatment decisions and recommendations are based on images, data, documents and/or other information transmitted through telecommunication systems. In telemedicine, there is a growing interest in mobile phones, both for image acquisition and for image viewing, because of the usability and economic efficiency of mobile phones. By using these advances in mobile telemedicine, it is possible to take an image with a mobile phone and view the image with another mobile phone by a remotely located physician or another specialist.
A physician or a specialist practicing telemedicine is responsible for the appropriate quality of his services. Medical opinions and recommendations can be given and medical decisions made if the quality of image/s, data or other information received is of sufficiently high standard and the systems used are adequately operational. The contrasts of patient images are relevant in telemedicine systems, but the contrast is not correctly reproduced by either conventional or mobile imaging systems.
Summary
According to a first aspect, there is provided a method for receiving image data in an apparatus; determining ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieving a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieving an ambient correcting value corresponding to the ambient illumination data; and applying the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data. In other words, an image captured by a first apparatus at a first location can be displayed by a second apparatus at a second location in a substantially similar form as the camera of the first apparatus originally captured the image. A calibration correction matrix and ambient correcting value are applied to correct original image data so that image data may be displayed at the second location as it was originally seen by the camera at the first location. The calibration correction matrix is produced in a calibration process, wherein the first and second apparatus are calibrated to each other and the ambient correcting value for ambient illumination data of the second location is produced by a calibration process, wherein the second apparatus is calibrated at the second location or at a corresponding condition, by a first apparatus.
According to a second aspect, there is provided an apparatus comprising a processor and a memory including computer program code, the memory and the computer program code being configured to, with the processor, cause the apparatus to receive image data; determine ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
According to a third aspect, there is provided a system comprising at least an image displaying device and an image capturing device, both comprising a processor and a memory including computer program code, the memory and the computer program code configured to, with the at least one processor, cause the system to: transmit image data from the image capturing device; receive image data in the image displaying device; determine ambient illumination condition of the image displaying device for obtaining ambient illumination data by the image displaying device; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device by the image displaying device; and retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data. According to a fourth aspect, there is provided an apparatus comprising means for receiving image data; means for determining ambient illumination condition of the apparatus for obtaining ambient illumination data retrieving ambient illumination data; means for retrieving a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; means for retrieving an ambient correcting value corresponding to the ambient illumination data; and means for applying the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
According to a fifth aspect, there is provided a computer program product stored on a storage medium comprising a computer program code configured to, with at least one processor, cause an apparatus to receive image data, determine ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
Brief Description of the Drawings
In the following, various embodiments are described in more detail with reference to the appended drawings, in which:
Fig. 1 shows a flow chart of image data correcting process according to an example embodiment;
Fig. 2 shows an apparatus arranged to receive and view images according to an example embodiment;
Fig. 3 shows a flow chart of a calibration process of two mobile apparatuses according to an example embodiment;
Fig. 4 shows a calibration process of two apparatuses according to an example embodiment; Fig. 5 shows an operation of an apparatus according to an example embodiment; and Fig. 6 shows a flow chart of an operation of an image correcting process according to an example embodiment.
Detailed Description of Some Embodiments In the following, several embodiments will be described in the context of mobile telemedicine and methods and apparatuses for the same. It is to be noted, however, that the invention is not limited to mobile telemedicine or mobile phones. In fact, the different embodiments have applications in any mobile environment where a reproduction quality of the viewed image is required. In addition to mobile phones, for example, smart phones and personal digital assistants (PDA) may also benefit from the use of the different embodiments. A device capturing and transmitting an image data and a device receiving and displaying corrected image data may not have to be identical or technically substantially similar. However, if these devices are identical or technically substantially similar, for example, the same model, or these devices behave identically, it might be beneficial to users of devices for displaying reproduced corrected images.
Figure 1 shows a flow chart of an image correcting process according to an example embodiment. According to this embodiment, an apparatus that is, for example, an image displaying device such as a mobile communication device, mobile phone, laptop, camera, personal digital assistant (PDA), tablet or other means to receive image data, to correct the received image data and to display corrected image data. The received image data may be received from an image capturing device that may have captured said image data or may have received said image data from some other device that is substantially technically identical to the image capturing device, for example, the same model. Both devices may comprise a camera or other means capturing image data and a display or other means displaying image data. The devices may have been calibrated to each other. One calibration method suitable to be used in this embodiment is disclosed in connection with figure 3. However, it is to be noted that the devices may not necessarily be calibrated to each other. Instead, it may be sufficient that the devices are calibrated to some other identical device e.g. the same product model or a device that technically behaves substantially identically or a device that is technically similar enough. The calibration may not need to be done device-to-device, but, for example, within a group comprising devices with the same product model. It may be sufficient that any two devices within that group have been calibrated to each other. After calibration image data captured by one device may be reproduced as captured on a display of any other device within that group.
At stage 100, the image displaying device receives image data e.g. from the image capturing device. The image displaying device may receive the image data, for example, as email, MMS or other suitable type depending on the selected channel. At stage 1 10, the image displaying device determines ambient illumination condition of the image displaying device for obtaining ambient illumination data. The image displaying device may determine the ambient illumination condition by an ambient light level information value from an ambient light sensor (ALS) and an ambient light color information value from the camera of the image displaying device, for example from a front-side camera. The image displaying device may store this ambient illumination data relating to ambient illumination condition in a memory. The memory may be any means for storing, for example, any internal memory of the apparatus or an external memory such as a micro secure digital (SD) card or a server.
In addition, it may be possible to arrange threshold values, lux levels, for ambient illumination data of the image displaying device and warn the user of the image displaying device if he is attempting to view an image in too low or too high ambient illumination conditions, or may turn the display of the image displaying device off if the data relating to ambient illumination condition is not within the threshold values. At stage 120, the image displaying device retrieves a calibration correction matrix from a memory. The memory may be some other means for storing or the same memory, wherein the data relating to ambient illumination condition is stored. The calibration correction matrix is a calibration profile mathematically defining the relation between red, green and blue (RGB) intensity values and/or brightness of display of the image displaying device and RGB intensity values of the camera of the image capturing device. The calibration correction matrix may comprise one coefficient that is determined during calibration. The coefficient may be used as a multiplier to correct brightness and/or RGB intensity values of the received image data. The calibration correction matrix may also comprise several coefficients, if the image is divided into parts, so that each coefficient acts as a multiplier for one part of the image. In addition, it is possible that the calibration correction matrix comprises a correction coefficient for each pixel of the image data to be corrected. If there is not the calibration correction matrix for the image displaying device in the memory, the user of the image displaying device may be requested to calibrate the image displaying device.
At stage 130, the image displaying device retrieves the ambient correcting value from a memory, wherein the ambient correcting value corresponds ambient illumination data of the determined ambient illumination condition of the image displaying device. There may have been stored a plurality of ambient correcting values corresponding to different ambient illumination data of ambient illumination conditions of image viewing in the memory, and these values are stored in connection with ambient calibration values for ambient illumination data of different ambient illumination conditions. According to another example embodiment, if there is no ambient correcting value that exactly corresponds ambient illumination data of ambient illumination condition, the image displaying device may retrieve at least two ambient correcting values that are the closest ones to the ambient illumination data of the ambient illumination condition and interpolate an ambient correcting value that corresponds to the ambient illumination data of the image displaying device.
According to example embodiment software of the image displaying device may ask the user of the image displaying device to calibrate the image displaying device in current ambient illumination condition if there is no ambient correcting value that corresponds to ambient illumination data of the determined ambient illumination condition in the memory or if interpolating may not be done. The calibration for the current ambient illumination condition may be executed on the devices, so that the image displaying device is being calibrated and the image capturing device is used as a calibrator. The calibration may be performed in the location where image viewing is going to take place with the image displaying device or in condition similar to the ambient illumination condition of the location of the image displaying device. The image displaying device is placed as it will be used for image viewing. The calibration software runs on both devices. The image capturing device is placed to mimic eyes of the user of the image displaying device. The calibration software of the image displaying device provides a calibration image to the display of the image displaying device. The image capturing device captures, without flash, an image of the calibration image and transmits the brightness value of the captured image to the image displaying device. Then calibration software of the image displaying device is arranged to compare brightness of the calibration image that was actually displayed on the display of the image displaying device against brightness of the image captured by the camera of the image capturing device and stores this offset data as an ambient correcting value. The image displaying device also stores its ALS data and ambient light color information value from the camera, for example, from a front-side camera, of the image displaying device as an ambient illumination data to refer this calibrated ambient correcting value, so that an ambient correcting value corresponding to ambient illumination data of a certain ambient illumination condition may be retrieved. This way, the software of the image displaying device may calculate at least one ambient correcting value for the current ambient illumination data including corrections related to the effect of the ambient light that was detected from the display of the image displaying device. The ambient correcting value for the current ambient illumination data is stored into the memory.
However, it may be that more than one calibration images are displayed and also more than one image of them may be captured. In addition, it may also be that both devices transmit their information about brightness values of at least one displayed image and at least one captured image to an external computing device, for example, to a server, that compares brightness values and calculates the ambient correcting value for adjusting brightness value of the received image data and further stores it for later use or transmits it to the image displaying device.
In addition, it may still be that the memory is not physically located in the image displaying device, in which case the memory checking is carried out by communicating with an external memory, such as a micro SD card or a server instead of accessing internal memory, and wherein the external memory may comprise a plurality of ambient correcting values for different ambient illuminations for similar devices as the image displaying device and/or for a plurality of different kind of devices.
At stage 140, the ambient correcting value and the calibration correction matrix is applied to the received image data. The software on the image displaying device may form a corrected image data based on the received image data by applying the ambient correcting value and the calibration correction matrix to received image data.
At stage 150, the corrected image data is displayed on the display of the image displaying device as an output image, wherein brightness and RGB intensity values are set according to instructions of the calibration correction matrix and the ambient correcting value.
According to another embodiment, the software of the image displaying device may further be arranged to determine ambient illumination condition at intervals during the displaying of the output image, for example, at one- minute intervals. If the ambient illumination condition changes comparing to earlier ambient illumination condition, the software retrieves a new ambient correcting value corresponding to the changed ambient illumination data of the ambient illumination condition from the memory and uses the ambient correcting value in connection with correcting the received image data so that the changed condition, for example, during the viewing is taken into account.
Figure 2 illustrates a simplified structure of an apparatus 200 capable of receiving and correcting image data according to an example embodiment. The apparatus may be, for example, a mobile terminal, a mobile phone, a smart phone, a PDA device, an Internet access device (Internet tablets), a laptop computer, personal computer (PC) or any other data processing device that may comprise means for displaying image data such as a display and means for image capturing such as a camera. The apparatus 200 comprises I/O means (I/O) 202, a central processing unit (CPU) 204, a memory (MEM) 206 and 256, and computer program code 216 residing in the memory 206 for implementing, for example, calibration. The memory 206 may comprise a read-only memory (ROM) portion and a rewriteable portion, such as a random access memory (RAM) and FLASH memory. The information used to communicate with different external parties, e.g. an image displaying apparatus calibrated with an image displaying apparatus or other identical apparatus that is calibrated with the image displaying apparatus, is transmitted through the I/O means (I/O) 202 to/from the CPU 204. The apparatus 200 may be implemented as a mobile station, so it includes a transceiver Tx/Rx (208), which communicates with the wireless network, typically with a base transceiver station (BTS) through an antenna 210, but also through Bluetooth® with another phone, for example, in connection with calibration process. Ul 212 equipment includes at least a display and a camera, such as a front side camera for determining of ambient illumination data of ambient illumination condition but it may also include a keypad and connecting means, for example, for a separate display, if there is a need to view the reproduced image also on a bigger display. The apparatus 200 may also comprise an ambient light sensor (ALS) 214 for determining of ambient illumination condition.
Figure 3 illustrates a method for calibration process for apparatuses A and B according to another example embodiment, wherein both apparatuses A and B comprise at lease a display and a camera. Calibration software may run on both apparatuses at the same time and the apparatuses may be located in a darkened room. At first, apparatus A is going to be calibrated and apparatus B acts as a calibrator. At stage 310, the calibration software of apparatus A displays a calibration image at the display of apparatus A, and at stage 31 1 , the camera of apparatus B captures an image of the calibration image without flash. Then, at stage 312, apparatus B transmits brightness and/or RGB intensity values of the captured image to apparatus A. At stage 313, the calibration software of apparatus compares brightness and/or RGB intensity values of the calibration image that was actually displayed against the brightness and/or RGB intensity values of the image captured by apparatus B. At stage 314 this data is stored to a memory. This stored data establishes the offset values of brightness and/or RGB intensity values of the display of apparatus A and the camera of apparatus B.
Apparatus B is calibrated and apparatus A acts as a calibrator. At stage 320, the calibration software of apparatus B displays a calibration image and at stage 321 apparatus A captures an image of the calibration image on the display of apparatus B without flash. At stage 322, apparatus B transmits brightness and/or RGB intensity values of the displayed image to apparatus A. At stage 323, the calibration software of apparatus A. compares the brightness and/or RGB intensity values of image that was actually displayed against a brightness value captured by the camera of apparatus A However, the calibration of apparatus B with apparatus A may not be necessary (stages 320 to 323) for creating a calibration correction matrix. It may be possible to create a calibration correction matrix on the basis of the calibration of apparatus A with apparatus B. However, when two or more calibrations are made, it may be possible to use average or weighted average values of brightness and/or RGB intensity values for creating a calibration correction matrix. It is also possible to calibrate apparatus A with one or more apparatus in addition to apparatus B, in which case, all apparatuses are technically substantially identical or the same model and averaged or weighted averaged values of brightness and/or RGB intensity values may be used for forming a calibration correction matrix.
At stage 330, the calibration software on apparatus A creates and stores a calibration correction matrix on the basis of offsets of these brightness and/or RGB intensity values of displayed and captured images. Then apparatus A forms and stores the calibration correction matrix, wherein the matrix mathematically defines the relation between brightness or RGB intensity values of the display and RGB intensity values of camera. This calibration correction value matrix is going to be used in connection with correcting received image data so that received image data may be reproduced on the display of apparatus A as it was originally captured.
According to another example embodiment there may be more than one calibration images displayed at different display brightness settings and also more than one image of them may be captured. According to another example embodiment both apparatuses A and B display at least one calibration image and capture at least one image before any data is transmitted for forming of the calibration correction matrix. According to another example embodiment both apparatuses A and B transmit brightness or RGB intensity values of displayed and captured images to an external computing device, for example, to a server or some other computer that compares offsets of values and calculates and form the calibration correction matrix and transmits the matrix to apparatus A or stores it for later use.
Figure 4 illustrates a calibration process between apparatuses A and B according to an exemplified embodiment, wherein apparatuses A and B are substantially similar from a technical point of view. There is calibration software running on both phones at the same time in a darkened room that is a good viewing condition. These apparatuses may communicate with each other by using Bluetooth® or any other means suitable for forming connection between apparatuses A and B. At first, the apparatus A is going to be calibrated and apparatus B is going to be used as a calibrator. Apparatus A displays calibration images at different display brightness settings and a camera 400 of apparatus B captures, without flash, at least one image from said calibration images. At next stage, apparatus B transmits the brightness and/or RGB intensity values of captured images to apparatus A e.g. by using Bluetooth®. After this, the calibration software of apparatus A compares the values of images that were actually displayed on the display 410 against the values of the captured images. On the possible second part of calibration process, apparatus B is going to be calibrated by apparatus A. The calibration software of apparatus B displays a series of calibration images on the display 420 of apparatus B again at different display brightness settings and apparatus A captures images of calibration images of apparatus B by a camera 430 without flash. At next stage, apparatus A transmits the brightness and/or RGB intensity values of captured images to apparatus B by Bluetooth®. After that, the calibration software of apparatus B compares the values of images that were actually displayed against the captured images. This offset data of values is transmitted to apparatus A e.g. via Bluetooth®. On the basis of differences between the brightness and/or RGB intensity values actually displayed images and captured images, the software of apparatus A forms a calibration correction matrix for correcting brightness offsets and RGB color intensity value offsets of cameras and displays. Figure 5 illustrates an operating situation of an apparatus for viewing received image data according to another example embodiment. A doctor using an apparatus B 510 needs comments about an X-ray 520 from a specialist using an apparatus A 530. Apparatuses B 510 and A 530 are technically substantially identical and they have been calibrated to each other. The doctor captures an image of the X-ray 520 by a camera 540 of his apparatus B 510 and sends image data of the X-ray 520 by a multimedia message to the apparatus A 530 of the specialist. The doctor uses his apparatus B 510 in a good viewing condition that is, for example, in a darkened room, but the specialist is out in bright sunshine when apparatus A 530 receives the image data of X-ray 520. Bright sunshine may decrease viewing conditions. So before viewing the received image of the X-ray 520 the apparatus A 530 determinates ambient illumination condition of apparatus A 530 from an ambient light level value from an ambient light sensor (ALS) 550 and an ambient light color information value from the camera 560 of apparatus A 530 for obtaining ambient illumination data. At next stage, apparatus A 530 retrieves an ambient correcting value corresponding to the ambient illumination data from a memory of apparatus A 530. Further, apparatus A 530 retrieves a calibration correction matrix from the memory of apparatus A 530. The calibration correction matrix is stored in the memory of apparatus A 530 in connection with the calibration process of apparatuses B 510 and A 530 or the calibration correction matrix is transmitted to apparatus A 530 after a calibration of two other phones that are substantially technically similar to apparatus A 510. After that, the apparatus A 530 uses the ambient correcting value and the calibration correction matrix to correct the received image data. After correcting, apparatus A 530 is capable of display the corrected image data of X-ray 520 as an output image 570 on the display and the output image 570 is shown as the camera 540 of apparatus B 510 saw it in the ambient illumination condition of apparatus B 510.
It is also possible, that apparatus A 530 or any other apparatus receiving image data to be displayed is calibrated with some other apparatus than the apparatus that transmits the image data. The apparatus used for calibrating is substantially technically similar to the apparatus 510, for example, the same model. According to another example embodiment the software of apparatus A 530 may include predetermined threshold values, lux levels, for ambient illumination data of the ambient illumination conditions and may warn the user of apparatus A 530 if he is attempting to display image data in too low or too high ambient illumination conditions or may turn the display off when the ambient illumination data is not within the threshold values.
It is also possible to arrange the software to determine ambient illumination condition of apparatus A 530 at intervals during the viewing of an image, for example, at one-minute intervals. If ambient illumination condition changes compared to earlier ambient illumination condition of apparatus 510, the software checks if ambient illumination data of the changed ambient illumination condition is still within threshold values and ambient illumination condition is suitable for viewing the image. Thus changed condition, for example, during the viewing may be taken into account. It is also possible to arrange the software to determine ambient illumination condition of apparatus A 530 at intervals, if the ambient illumination data is at first determined to be outside the threshold values and ambient illumination condition is not suitable for displaying the image. In which case, the ambient illumination conditions may be re-determined until condition changes suitable for displaying the image or the ambient illumination conditions may be re-determined at predetermined times, for example, ten times, if condition is not changed suitable for viewing the image before that.
Figure 6 shows a method for image data correcting process according to an embodiment. At stage 600, image data is received. At stage 610, ambient illumination condition of an apparatus is determined from an ambient light sensor and from a camera of the apparatus for obtaining ambient illumination data. At stage 620, a calibration correction matrix is retrieved. At stage 630, an ambient correcting value for the ambient illumination data is retrieved. At stage 640, the calibration correction matrix and the ambient correction value is applied to received image data. In addition to the above described embodiments, it is also possible to apply the above mentioned methods to correct metameric failures and thus display colors correctly. According to the above described embodiments it is possible to calibrate a camera and a display of an apparatus by using another substantially identical apparatus as a calibrator so that an image may be captured with one apparatus and displayed on another apparatus in the same way the camera saw it on the apparatus capturing the image data. There is no need to use calorimeters or any other conventional methods or devices for calibration of the apparatus displaying an image captured by some other apparatus.
The various embodiments can be implemented with the help of computer program code that resides in a memory and causes the relevant apparatuses to carry out the invention. For example, a terminal device may comprise circuitry and electronics for handling, receiving and transmitting data, computer program code in a memory, and a processor that, when running the computer program code, causes the terminal device to carry out the features of an embodiment.
While the invention has been described in connection with a number of embodiments and implementations, the invention is not so limited but covers various obvious modifications and equivalent arrangements, which fall within the scope of the appended claims. Although features of the invention are expressed in certain combinations among the claims, it is contemplated that these features can be arranged in any combination and order.

Claims

Claims:
1 . A method comprising: receiving image data in an apparatus; determining ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieving a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieving an ambient correcting value corresponding to the ambient illumination data; and applying the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
2. A method according to claim 1 further comprising: displaying the corrected image data on a display of the apparatus as captured by the image capturing device.
3. A method according to claim 1 or 2 further comprising retrieving the calibration correction matrix from a memory, said calibration correction matrix comprising values for adjusting brightness or RGB intensity value of the received image data, and wherein the calibration correction matrix having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus.
4. A method according to claim 3, wherein producing the calibration correction matrix comprises: displaying at least one calibration image on the display of the apparatus; capturing at least one image of said at least one calibration image on the display of the apparatus by the calibration apparatus, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of the apparatus; transmitting brightness and/or RGB intensity values of said at least one captured image from the calibration apparatus to the apparatus; comparing the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and forming the calibration correction matrix on the basis of offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image at the apparatus.
5. A method according to claim 4, wherein producing the calibration correction matrix further comprises: displaying at least one calibration image on the display of the calibration apparatus; capturing at least one image of said at least one calibration image on the display of the calibration apparatus by the apparatus, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of said calibration apparatus; transmitting brightness and/or RGB intensity values of said at least one displayed calibration image from the calibration apparatus to the apparatus; comparing the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; applying offsets between brightness and/or RGB intensity values of said at least one calibration image displayed by the calibration apparatus and said at least one captured image by the apparatus in forming of the calibration correction matrix.
6. A method according to any of the claims 1 to 5 further comprising obtaining the ambient illumination data from an ambient light sensor (ALS) and from the camera of the apparatus.
7. A method according to any of the claims 1 to 6, wherein retrieving the ambient correcting value from a memory, said ambient correcting value comprising values for adjusting brightness value of the received image data, and wherein the ambient correcting value having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus in condition similar to the ambient illumination condition.
8. A method according to claim 7, wherein producing the ambient correcting value comprises: determining ambient illumination condition of the apparatus for obtaining ambient illumination data; displaying at least one calibration image on the display of the apparatus; capturing at least one image of said at least one calibration image on the display of the apparatus by a calibration apparatus, said at least one image comprising data on brightness value of said at least one calibration image of said apparatus; transmitting brightness value of said at least one calibration image from the calibration apparatus to the apparatus; comparing the brightness value of said at least one calibration image against the brightness value of said at least one captured image at the apparatus; and forming the ambient correcting value for the ambient illumination data on the basis of offsets between brightness values of said at least one calibration image and said at least one captured image at the apparatus.
9. A method according to any of the claims 1 to 8, wherein the received image data is transmitted by the calibration apparatus.
10. An apparatus comprising at least one processor and a memory including computer program code, the memory and the computer program code being configured to, with the processor, cause the apparatus to: receive image data; determine ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
1 1 . An apparatus according to claim 10, wherein the apparatus further comprises a display and is further caused to display the corrected image data on the display as captured by the image capturing device.
12. An apparatus according to claim 10 or 1 1 , wherein said calibration correction matrix is retrieved from a memory, said calibration correction matrix comprising values for adjusting brightness and/or RGB intensity value of the received image data, and wherein the calibration correction matrix having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus.
13. An apparatus according to claim 12, wherein the memory and the computer program code being configured to in connection with producing the calibration correction matrix, with the processor, cause the apparatus to: display at least one calibration image on the display of the apparatus; receive brightness and/or RGB intensity values of at least one captured image of said at least one displayed calibration image from the calibration apparatus, wherein said at least one captured image is captured by the calibration apparatus; compare the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and form the calibration correction matrix on the basis of offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image at the apparatus.
14. An apparatus according to claim 13, wherein the memory and the computer program code being configured to in connection with producing the calibration correction matrix, with the processor, cause the apparatus further to: capture at least one image of at least one calibration image on the display of the calibration apparatus by the apparatus, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of said calibration apparatus; receive brightness and/or RGB intensity values of said at least one calibration image from the calibration apparatus; compare the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and apply offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image in forming of the calibration correction matrix.
15. An apparatus according to any of the claims 10 to 14, wherein the ambient illumination data is obtained from an ambient light sensor (ALS) and from the camera of the apparatus.
16. An apparatus according to any of the claims 10 to 14, wherein the ambient correcting value is retrieved from the memory, said ambient correcting value comprising at least one value for adjusting brightness value of the received image data, and wherein the ambient correcting value having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus in condition similar to the ambient illumination condition.
17. An apparatus according to claim 16, wherein the memory and the computer program code being configured to in connection with producing the ambient correcting value, with the processor, cause the apparatus to: determine ambient illumination condition of the apparatus for obtaining ambient illumination data; display at least one calibration image on the display of the apparatus; receive brightness value of at least one captured image of said at least one displayed calibration image from the calibration apparatus, wherein said at least one captured image is captured by the calibration apparatus; compare the brightness value of said at least one calibration image against the brightness value of said at least one captured image at the apparatus; and form the ambient correcting value for the ambient illumination data on the basis of offsets between brightness values of said at least one calibration image and said at least one captured image at the apparatus.
18. An apparatus according to claim 16 or 17, wherein the memory comprises ambient correction values for a plurality of ambient illumination data.
19. An apparatus according to any of the claims 12 to 18, wherein the memory is an internal memory of the apparatus.
20. An apparatus according to any of the claims 12 to 18, wherein the memory is an external memory such as a micro secure digital (SD) card or a server.
21 . An apparatus according to any of the claims 10 to 20, wherein the apparatus is received image data from the calibration apparatus.
22. An apparatus according to any of the claims 10 to 21 , wherein the apparatus is a mobile phone.
23. A system comprising at least an image displaying device and an image capturing device, both comprising a processor and a memory including computer program code, the memory and the computer program code configured to, with the at least one processor, cause the system to: transmit image data from the image capturing device; receive image data in the image displaying device; determine ambient illumination condition of the image displaying device for obtaining ambient illumination data by the image displaying device; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device by the image displaying device; and retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
24. A system according to claim 23, wherein the image displaying device further comprises a display and is further caused to display the corrected image data on the display as captured by the image capturing device.
25. A system according to claim 23 or 24, wherein said calibration correction matrix is retrieved from a memory, said calibration correction matrix comprising values for adjusting brightness or RGB intensity value of the received image data, and wherein the calibration correction matrix having been produced by calibrating the image displaying device with a calibration device that is substantially technically identical to the image displaying device.
26. A system according to claim 25, wherein the memory and the computer program code being configured to in connection with producing the calibration correction matrix, with the processor, cause the system to: display at least one calibration image on the display of the image displaying device; capture at least one image of said at least one calibration image on the display of the image displaying device by the calibration device, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of the image displaying device; transmit brightness and/or RGB intensity values of said at least one captured image from the calibration device to the image displaying device; compare the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the image displaying device; and form the calibration correction matrix on the basis of offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image at the image displaying device.
27. A system according to claim 26, wherein the memory and the computer program code being configured to in connection with producing the calibration correction matrix, with the processor, cause the system further to: display at least one calibration image on the display of the calibration device; capture at least one image of said at least one calibration image on the display of the calibration device by the image displaying device, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of said calibration device; transmit brightness and/or RGB intensity values of said at least one displayed calibration image from the calibration device to the image displaying device; compare the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the image displaying device; and apply offsets between brightness and/or RGB intensity values of said at least one calibration image displayed by the calibration device and said at least one captured image by the image displaying device in forming of the calibration correction matrix.
28. A system according to any of the claims 23 or 27, wherein the ambient illumination data is obtained from an ambient light sensor (ALS) and from the camera of the image displaying device.
29. A system according to any of the claims 23 to 28, wherein the ambient correcting value is retrieved from a memory, said ambient correcting value comprising at least one value for adjusting brightness value of the received image data, and wherein the ambient correcting value having been produced by calibrating the image displaying device by a calibration device that is substantially technically identical to the image displaying device in condition similar to the ambient illumination condition.
30. A system according to claim 29, wherein the memory and the computer program code being configured to in connection with producing the ambient correcting value, with the processor, cause the system to: determine ambient illumination condition of the apparatus for obtaining ambient illumination data; display at least one calibration image on the display of the image displaying device; capture at least one image of said at least one calibration image on the display of the image displaying device by a calibration device, said at least one image comprising data on brightness value of said at least one calibration image of said image displaying device; transmit brightness value of said at least one calibration image from the calibration device to the image displaying device; compare the brightness value of said at least one calibration image against the brightness value of said at least one captured image at the image displaying device; and forming the ambient correcting value for determined ambient illumination data on the basis of offsets between brightness values of said at least one calibration image and said at least one captured image at the image displaying device.
31 . A system according to any of the claims 23 to 30, wherein the image capturing device is the calibration device.
32. A system according to any of the claims 23 to 32, wherein the image displaying device and the image capturing device are mobile phones.
33. An apparatus comprising: means for receiving image data; means for determining ambient illumination condition of the apparatus for obtaining ambient illumination data retrieving ambient illumination data; means for retrieving a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; means for retrieving an ambient correcting value corresponding to the ambient illumination data; and means for applying the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
34. An apparatus according to claim 33, wherein the apparatus further comprises means for displaying the corrected image data as captured by the image capturing device.
35. An apparatus according to claim 33 or 34, wherein the apparatus further comprises means for storing the calibration correction matrix, and wherein said calibration correction matrix comprising instructions for adjusting brightness or RGB intensity value of the received image data is retrieved from means for storing and wherein the calibration correction matrix having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus.
36. An apparatus according to claim 35, comprises further at least one means for controlling, and wherein means for storing comprises computer program code, the means for storing and the computer program code being configured to in connection with producing the calibration correction matrix, with the means for controlling, cause the apparatus to: display at least one calibration image; receive brightness and/or RGB intensity values of at least one captured image of said at least one calibration image from the calibration apparatus, wherein said at least one captured image is captured by the calibration apparatus; compare the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and form the calibration correction matrix on the basis of offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image at the apparatus.
37. An apparatus according to claim 36, the means for storing and the computer program code being configured to in connection with producing the calibration correction matrix, with the means for controlling, cause the apparatus further to: capture at least one image of at least one calibration image on the display of the calibration apparatus by the apparatus, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of said calibration apparatus; receive brightness and/or RGB intensity values of said at least one calibration image from the calibration apparatus to the apparatus; compare the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and apply offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image in forming of the calibration correction matrix.
38. An apparatus according to any of the claims 33 or 37, wherein the ambient illumination data is obtained from an ambient light sensor (ALS) and from the camera of the apparatus.
39. An apparatus according to any of the claims 33 or 38, wherein the apparatus further comprises means for storing ambient correcting value, said ambient correcting value comprising at least one value for adjusting brightness value of the received image data, and wherein the ambient correcting value having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus in condition similar to the ambient illumination condition.
40. An apparatus according to claim 39, the means for storing and the computer program code being configured to in connection with producing the ambient correcting value, with the means for controlling, cause the apparatus to: determine ambient illumination condition of the apparatus for obtaining ambient illumination data; display at least one calibration image; receive brightness value of at least one captured image of said at least one calibration image from the calibration apparatus, wherein said at least one captured image is captured by the calibration apparatus; compare the brightness value of said at least one calibration image against the brightness value of said at least one captured image; and form the ambient correcting value for determined ambient illumination data on the basis of offsets between brightness values of said at least one calibration image and said at least one captured image.
41 . An apparatus according to any of the claims 39 to 40, wherein the means for storing ambient correcting value comprises a plurality of ambient correcting values.
42. An apparatus according to any of the claims 33 to 41 , wherein the apparatus is a mobile phone.
43. A computer program product stored on a storage medium comprising a computer program code configured to, with at least one processor, cause an apparatus to: receive image data; determine ambient illumination condition of the apparatus for obtaining ambient illumination data; retrieve a calibration correction matrix comprising values for adjusting offsets between an image capturing device and an image displaying device; retrieve an ambient correcting value corresponding to the ambient illumination data; and apply the calibration correction matrix and the ambient correcting value to the received image data in order to obtain corrected image data.
44. A computer program according to claim 43 comprising computer instructions further for: displaying the corrected image data on the display as captured by the image capturing device.
45. A computer program according to claim 43 or 44 comprising computer instructions for retrieve the calibration correction matrix from a memory, the calibration correction matrix calibration correction matrix comprising values for adjusting brightness or RGB intensity value of the received image data, and wherein the calibration correction matrix having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus
46. A computer program according to claim 45, wherein producing the calibration correction matrix comprises at least computer instructions for: displaying at least one calibration image on the display of the apparatus; receiving brightness and/or RGB intensity values of at least one captured image of said at least one displayed calibration image from the calibration apparatus, wherein said at least one captured image is captured by the calibration apparatus; comparing the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and forming the calibration correction matrix on the basis of offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image at the apparatus.
47. A computer program according to claim 46, wherein producing the calibration correction matrix comprises further computer instructions for: capturing at least one image of at least one calibration image on the display of the calibration apparatus by the apparatus, said at least one captured image comprising data on brightness and/or RGB intensity values of said at least one calibration image of said calibration apparatus; receiving brightness and/or RGB intensity values of said at least one calibration image from the calibration apparatus; comparing the brightness and/or RGB intensity values of said at least one calibration image against the brightness and/or RGB intensity values of said at least one captured image at the apparatus; and applying offsets between brightness and/or RGB intensity values of said at least one calibration image and said at least one captured image in forming of the calibration correction matrix.
48. A computer program according to any of the claims 43 to 47, wherein the ambient illumination data is obtained from an ambient light sensor (ALS) and from the camera of the image displaying device
49. A computer program according to any of the claims 43 to 48 comprising computer instructions for retrieve the ambient correcting value from a memory, the ambient correcting value comprising values for adjusting brightness value of the received image data, and wherein the ambient correcting value having been produced by calibrating the apparatus with a calibration apparatus that is substantially technically identical to the apparatus in condition similar to the ambient illumination condition.
50. A computer program according to claim 49, wherein producing the ambient correcting value comprises at least computer instructions for: determing ambient illumination data of the apparatus; displaying at least one calibration image on the display of the apparatus; receiving brightness value of at least one captured image of said at least one displayed calibration image from the calibration apparatus, wherein said at least one captured image is captured by the calibration apparatus; comparing the brightness value of said at least one calibration image against the brightness value of said at least one captured image at the apparatus; and forming the ambient correcting value for determined ambient illumination data on the basis of offsets between brightness values of said at least one calibration image and said at least one captured image at the apparatus
51 . A computer program according to claim 49 or 50, wherein the memory comprises ambient correction values for a plurality of ambient illumination data.
52. A computer program according to any of the claims 45 to 51 , wherein the memory is an internal memory of the apparatus receiving the image data.
53. A computer program according to any of the claims 45 to 51 , wherein the memory is an external memory such as a micro secure digital (SD) card or a server.
54. A computer program according to any of the claims 43 to 53, wherein the apparatus is a mobile phone.
55. A computer program according to any of the claims 43 to 54, wherein the computer program is stored in at least one of the following:
an apparatus;
a mobile phone;
a memory;
a micro secure digital (SD) card.
PCT/FI2010/050986 2010-12-01 2010-12-01 Calibrating method and apparatus WO2012072855A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3544271A4 (en) * 2016-11-17 2019-09-25 JRD Communication (Shenzhen) Ltd Mobile terminal-based flash assembly and control system and control method thereof

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2363024A (en) * 2000-04-07 2001-12-05 Hewlett Packard Co Calibrating an imaging system
US20030007077A1 (en) * 2001-07-09 2003-01-09 Logitech Europe S.A. Method and system for custom closed-loop calibration of a digital camera
US20050122406A1 (en) * 2003-12-09 2005-06-09 Voss James S. Digital camera system and method having autocalibrated playback viewing performance
US20070024576A1 (en) * 2004-01-13 2007-02-01 Hassan Paddy A Correction arrangements for portable devices with oled displays
US20080259289A1 (en) * 2004-09-21 2008-10-23 Nikon Corporation Projector Device, Portable Telephone and Camera
US20090009607A1 (en) * 2005-02-24 2009-01-08 Bang & Olufsen A/S System for Providing Uniform Image Quality in Displays for Image Reproduction
US20100245590A1 (en) * 2007-11-23 2010-09-30 Cazier Robert P Camera sensor system self-calibration

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2363024A (en) * 2000-04-07 2001-12-05 Hewlett Packard Co Calibrating an imaging system
US20030007077A1 (en) * 2001-07-09 2003-01-09 Logitech Europe S.A. Method and system for custom closed-loop calibration of a digital camera
US20050122406A1 (en) * 2003-12-09 2005-06-09 Voss James S. Digital camera system and method having autocalibrated playback viewing performance
US20070024576A1 (en) * 2004-01-13 2007-02-01 Hassan Paddy A Correction arrangements for portable devices with oled displays
US20080259289A1 (en) * 2004-09-21 2008-10-23 Nikon Corporation Projector Device, Portable Telephone and Camera
US20090009607A1 (en) * 2005-02-24 2009-01-08 Bang & Olufsen A/S System for Providing Uniform Image Quality in Displays for Image Reproduction
US20100245590A1 (en) * 2007-11-23 2010-09-30 Cazier Robert P Camera sensor system self-calibration

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3544271A4 (en) * 2016-11-17 2019-09-25 JRD Communication (Shenzhen) Ltd Mobile terminal-based flash assembly and control system and control method thereof
US10764420B2 (en) 2016-11-17 2020-09-01 Jrd Communication (Shenzhen) Ltd Flash assembly of mobile terminal, control system thereof and control method thereof

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