JP5200890B2 - Image processing apparatus and control method thereof - Google Patents

Description

  The present invention relates to an image processing apparatus and a control method thereof, and in particular, an image processing apparatus and a control method thereof that can effectively remove image noise regardless of whether the image source is a moving image source or a still image source. About.

  Some image processing apparatuses such as printers can print and display as still images not only when the image source is a still image source but also when it is a moving image source. For example, in a printer, when the image source is a moving image source, a still image is generated based on the moving image source, and the generated still image can be printed.

  Here, for a still image obtained from a still image source, as proposed in Japanese Patent Application Laid-Open No. 2003-189236 (Patent Document 1), conditions such as sensitivity at the time of image acquisition are acquired, and this image acquisition is performed. There is a technique for efficiently reducing image noise based on the conditions at the time.

  On the other hand, the moving image source is compressed at a higher compression rate than the still image source, and in particular, the compression rate of the color difference component is higher. Image noise is also characterized in that a still image obtained from a still image source has a lot of white noise due to lack of sensitivity, but a still image obtained from a moving image source has a lot of mosquito noise due to image quality degradation during high compression.

As described above, since the nature of the generated image noise differs depending on whether the image source is a moving image source or a still image source, it is desirable to appropriately remove the image noise depending on the type of the image source. ing.
JP 2003-189236 A

  Therefore, the present invention has been made in view of the above problems, and an image processing apparatus capable of effectively removing image noise and its control regardless of whether the image source is a moving image source or a still image source. It aims to provide a method.

In order to solve the above problems, an image processing apparatus according to the present invention provides:
Image source acquisition means for acquiring an image source of a video source or a still image source;
Determining means for determining whether the image source acquired by the image source acquiring means is a moving image source or a still image source;
If the determination means determines that the source is a moving image source, the matrix size of the smoothing range used in the noise removal processing of the color difference plane is larger than the matrix size of the smoothing range used in the noise removal processing of the luminance plane. If it is determined that the image is a still image source by the determination means, the size of the matrix of the smoothing range used in the noise plane noise removal processing is set to the smoothing used in the color difference plane noise removal processing. Setting means for setting to be larger than the size of the matrix of the conversion range;
Luminance plane noise removal processing and chrominance plane noise removal processing are performed on image data based on the image source acquired by the image source acquisition unit with the size of the smoothing range matrix set by the setting unit. Noise removal processing execution means;
It is characterized by providing.

In this case, the image data of the image source acquired by the image source acquisition unit is further provided with a first conversion unit that converts the image data of the image source into a representation of the color space of YCbCr.
The noise removal processing execution unit may perform the noise removal processing based on the image data converted into the YCbCr color space representation by the first conversion unit.

  In this case, the first conversion means may convert the image data expressed in the RGB color space into an expression in the YCbCr color space.

  In this case, a second conversion unit that converts the image data from which noise has been removed by the noise removal processing execution unit into image data expressed in an RGB color space may be further provided.

  The image processing apparatus may further include a print execution unit that executes printing based on the image data that has been subjected to noise removal processing by the noise removal processing execution unit.

An image processing apparatus control method according to the present invention includes:
Acquiring an image source of a video source or a still image source;
Determining whether the acquired image source is a video source or a still image source;
When it is determined that the image source is a moving image source, the matrix size of the smoothing range used in the noise removal processing of the color difference plane is larger than the matrix size of the smoothing range used in the noise removal processing of the luminance plane. If the image source is determined to be a still image source, the size of the smoothing range matrix used in the noise plane noise removal processing is set to the smoothing used in the color difference plane noise removal processing. A step of setting the size to be larger than the size of the matrix of the conversion range;
A step of performing a noise plane noise removal process and a color difference plane noise removal process on image data based on the acquired image source at the set smoothing range matrix size;
It is characterized by providing.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below do not limit the technical scope of the present invention.

  FIG. 1 is a block diagram illustrating an example of the internal configuration of the image processing apparatus 10 according to the present embodiment. As can be seen from FIG. 1, the image processing apparatus 10 according to the present embodiment is configured by a printer, and more specifically, is configured by a color inkjet printer. However, the image processing apparatus 10 is not limited to a printer, and may be configured by an image display apparatus such as a photo viewer.

  As shown in FIG. 1, the image processing apparatus 10 includes a CPU (Central Processing Unit) 20, a ROM (Read Only Memory) 22, a card interface 24, a communication interface 26, a screen interface 28, and a device control unit 30. These are connected to each other via an internal bus 32.

  A random access memory (RAM) 34 that is a dedicated volatile storage device is connected to the CPU 20. For example, the CPU 20 performs various controls of the image processing apparatus 10 by reading and executing various programs stored in the ROM 22. When executing the program, the CPU 20 stores temporary data in the RAM 34 as necessary.

  The ROM 22 is an example of a nonvolatile storage device, and various programs and data in the image processing device 10 are stored in a nonvolatile manner. The card interface 24 is an interface for inserting and using a card-type external device 100 such as a PC card in the image processing apparatus 10. For example, in the case of a PC card, there are various types such as a flash memory card, a hard disk, a SCSI card, and a modem card.

  The communication interface 26 is an interface for connecting various types of external devices 102 such as an imaging device such as a camera or a notebook or desktop personal computer to the image processing apparatus 10. As a connection standard between the image processing apparatus 10 and the external device 102, a wired standard such as USB or RS232C may be used, or a wireless standard such as IrDA or Bluetooth may be used.

  The screen interface 28 is an interface for a display screen 36 provided in the image processing apparatus 10. The display screen 36 is configured by, for example, an LCD (Liquid Crystal Display). In the present embodiment, for example, a reduced image for allowing the user to arbitrarily select an image to be printed is displayed on the display screen 36. The display screen 36 is composed of a touch panel, and also serves as a user interface for a user to input an instruction to the image processing apparatus 10.

  The apparatus control unit 30 is connected to a RAM 40, a print head 42, a carriage 44, a paper feed mechanism 46, and a scanner 48. The print head 42, the carriage 44, the paper feed mechanism 46, and a scanner. Mechanical control of 48 is performed. The RAM 40 is a volatile storage device dedicated to the device control unit 30 and temporarily stores data necessary for the device control unit 30 to perform these mechanical controls. The device control unit 30 is configured by, for example, an ASIC (Application Specific IC).

  In the present embodiment, in particular, the apparatus control unit 30 performs overall control of printing using the print head 42, the carriage 44, and the paper feed mechanism 46. That is, printing is performed on a print medium such as paper while ejecting printing ink from the print head 42 mounted on the carriage 44 and alternately moving the carriage 44 in the scanning direction (direction intersecting the paper feeding direction). The paper feed mechanism 46 performs printing on the print medium by sequentially feeding a print medium such as paper in the paper feed direction in accordance with printing by the carriage 44.

  The apparatus control unit 30 also performs control at the time of image reading using the scanner 48. For example, a document set on the image reading surface of the scanner 48 by a user is read using a line image sensor, and a series of processes for temporarily storing them as image data in the RAM 44 is controlled.

  Next, an image noise removal process executed by the image processing apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart for explaining an example of image noise removal processing executed by the image processing apparatus 10. This image noise removal process is realized by the CPU 20 reading and executing an image noise removal process program stored in the ROM 22, for example. The image noise removal process is a process executed as a part of the print execution process when the user designates an image to be printed, a layout, or the like and instructs the image processing apparatus 10 to print. It is.

  First, as shown in FIG. 2, the image processing apparatus 10 acquires image source information (step S10). For example, image data of an image source stored in the card type external device 100 is read. The image source file to be read is designated in advance by the user, or automatically designated based on processing executed by the image processing apparatus 10.

  Next, the image processing apparatus 10 determines whether or not the read image source is a moving image source (step S12). That is, the image processing apparatus 10 determines whether the read image source is a moving image source or a still image source. In this embodiment, this determination is made by using the extension of the file name. For example, if the extension of the file name is mpg, rm, avi, mov, etc., it is determined that the file is a moving image file and a moving image source. On the other hand, if the extension of the file name is jpg, gif, png, bmp or the like, it is determined that the file is a still image file and a still image source.

  Note that it may be determined whether the image source is a moving image source or a still image source based on information other than the file name extension. For example, when the data in the file includes information indicating whether it is a moving image file or a still image file, the determination may be made based on this data.

  When it is determined that the read image source is a moving image source (step S12: YES), the image processing apparatus 10 sets the luminance correction level to “1” and the color difference correction level to “5” ( Step S14).

  On the other hand, when it is determined that the read image source is not a moving image source (step S12: NO), that is, when it is determined that it is a still image source, the image processing apparatus 10 sets the luminance correction level to “3”. The color difference correction level is set to “1” (step S16).

  After step S14 or step S16, the image processing apparatus 10 converts the image data expressed in the RGB color space into a representation in the YCbCr color space (step S18).

  Next, the image processing apparatus 10 performs noise removal on the Y plane of the image data obtained in step S18 (step S20). When removing the noise, a smoothing process is performed. The size of the matrix of the smoothing range used in the smoothing process varies depending on the level set in step S14 or step S16.

  FIG. 3 is a diagram illustrating an example of the level-by-level smoothing range table TB10 that holds the relationship between the level set in step S14 or step S16 and the size of the smoothing range matrix. In the present embodiment, the level-specific smoothing range table TB10 is stored in, for example, the ROM 22, and the image processing apparatus 10 refers to this as necessary.

  As shown in FIG. 3, in this embodiment, level 1 performs smoothing processing using a matrix of 3 vertical pixels × 3 horizontal pixels, and level 2 converts a matrix of 7 vertical pixels × 7 horizontal pixels. In level 3, smoothing is performed using a matrix of vertical 9 pixels × horizontal 9 pixels, and in level 4, smoothing is performed using a matrix of vertical 15 pixels × horizontal 15 pixels. In level 5, smoothing processing is performed using a matrix of 21 vertical pixels × 21 horizontal pixels. In the smoothing process, the value of the operator of each pixel in the matrix of the smoothing range is set and weighted is arbitrary.

  Next, as shown in FIG. 2, the image processing apparatus 10 removes noise from the Cb plane of the image data obtained in step S18 (step S22), and removes noise from the Cr plane (step S24). A smoothing process is also performed at the time of noise removal in step S22 and step S24, and the size of the matrix of the smoothing range used in the smoothing process is also set in step S14 or step S16 as in step S20. Based on the level.

  Next, the image processing apparatus 10 converts the image data subjected to noise removal expressed in the YCbCr color space into an expression in the RGB color space (step S26). That is, the image data is restored to the original representation of the RGB color space. Thereby, the image noise removal process according to the present embodiment ends.

  After the image noise removal processing is completed, the image processing apparatus 10 performs printing based on the image data from which noise has been removed by the image noise removal processing. That is, printing is performed by driving the print head 42, the carriage 44, and the paper feed mechanism 46 based on the image data from which noise has been removed. As a result, a still image is printed on the print medium.

  As described above, according to the image noise removal processing according to the present embodiment, when the image source is a still image source, the image processing apparatus 10 sets the luminance correction level to “3” and the color difference correction level. Is set to “1” so that the smoothing filter is applied only to the non-edge portion of the luminance plane (Y plane). For this reason, it is possible to effectively reduce random noise in the luminance portion of the still image.

  On the other hand, when the image source is a moving image source, the image processing apparatus 10 sets the color correction plane (Cb plane and Cr) by setting the luminance correction level to “1” and the color difference correction level to “5”. A smoothing filter with a large range is applied to the plane. For this reason, the block noise of the color difference part of a moving image can be reduced effectively.

  As described above, when the image source is a moving image source, the size of the smoothing range matrix used in the noise removal processing of the color difference plane is larger than the size of the smoothing range matrix used in the noise removal processing of the luminance plane. If the image source is determined to be a still image source, the size of the smoothing range matrix used in the luminance plane noise removal processing is set to the smoothing used in the color difference plane noise removal processing. By setting to be larger than the size of the matrix of the range, it is possible to effectively remove moving image-specific image noise and still image-specific image noise.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, when the image source is a still image source, the luminance correction level is set to “3” and the color difference correction level is set to “1”, while the image source is a moving image source. In some cases, the luminance correction level is set to “1” and the color difference correction level is set to “5”. What kind of levels should be set for the luminance correction level and the color difference correction level? It can be changed arbitrarily. In the present embodiment, these setting levels are divided into five stages, but it is possible to arbitrarily set the number of stages. Further, the size of the matrix for setting the smoothing range can be arbitrarily changed.

  In the above-described embodiment, the case where the image source image data acquired in step S10 is expressed in the RGB color space is described as an example. It may be expressed in space. Furthermore, when the acquired image data of the image source is expressed in the YCbCr color space, the conversion process in step S18 is unnecessary, and the conversion process for returning to the original color space in step S26 is also unnecessary. It becomes.

  Furthermore, for the image noise removal process described in the above-described embodiment, a program for executing this image noise removal process is recorded on a flexible disk, a CD-ROM (Compact Disc-Read Only Memory), a ROM, a memory card, or the like. It is possible to record on a medium and distribute in the form of a recording medium. In this case, the above-described embodiment can be realized by causing the image processing apparatus 10 to read and execute the program recorded on the recording medium.

  The image processing apparatus 10 may include other programs such as an operating system or another application program. In this case, in order to utilize another program included in the image processing apparatus 10, a program including an instruction for calling a program that realizes processing equivalent to the above-described embodiment from among the programs included in the image processing apparatus 10 May be recorded on a recording medium.

  Furthermore, such a program can be distributed not as a recording medium but as a carrier wave through a network. The program transmitted in the form of a carrier wave on the network is taken into the image processing apparatus 10, and the above-described embodiment can be realized by executing this program.

  Further, when a program is recorded on a recording medium or transmitted as a carrier wave on a network, the program may be encrypted or compressed. In this case, the image processing apparatus 10 that has read the program from the recording medium or the carrier wave needs to execute the program after decoding or decompressing the program.

  In the above-described embodiment, the case where the image noise removal process is realized by software has been described as an example. However, each of these processes may be realized by hardware such as an ASIC (Application Specific IC). Furthermore, each of these processes may be realized by cooperation of software and hardware.

  FIG. 4 is a block diagram for explaining an example of the configuration of the image processing apparatus 10 when the above-described image noise removal processing is realized by hardware. As shown in FIG. 4, the image processing apparatus 10 in FIG. 4 includes an image source acquisition unit 200, a determination unit 202, a setting unit 204, and a noise removal processing execution unit 206. They are connected to each other.

  The image source acquisition unit 200 acquires an image source of a moving image source or a still image source. For example, the image source acquisition unit 200 reads and acquires the image source stored in the image source storage unit 220. The image source storage unit 220 includes, for example, the card type external device 100 and the external device 102 described above.

  The determination unit 202 determines whether the image source acquired by the image source acquisition unit 200 is a moving image source or a still image source. When the determination unit 202 determines that the image source is a moving image source, the setting unit 204 determines the size of the matrix of the smoothing range used in the color difference plane noise removal process by the luminance plane noise removal process. It is set to be larger than the matrix size of the smoothing range to be used. For example, as in the above-described embodiment, by setting the luminance correction level to “1”, the luminance plane noise is removed using a matrix of 3 vertical pixels × 3 horizontal pixels, and the color difference correction level is set. By setting “5” to “5”, it is set so that noise removal processing of the color difference plane is performed using a matrix of 21 vertical pixels × 21 horizontal pixels.

  On the other hand, when the determination unit 204 determines that the image source is a still image source, the setting unit 204 sets the size of the smoothing range matrix used in the noise plane noise removal processing to the color difference plane noise removal processing. Is set to be larger than the size of the matrix of the smoothing range used in. For example, as in the above-described embodiment, by setting the luminance correction level to “3”, it is set to perform noise plane noise removal processing using a matrix of vertical 9 pixels × horizontal 9 pixels, and the color difference correction level. By setting “1” to “1”, it is set to perform noise removal processing of the color difference plane using a matrix of 3 vertical pixels × 3 horizontal pixels.

  The noise removal processing execution unit 206 performs luminance plane noise removal processing on the image data based on the image source acquired by the image source acquisition unit 200 with the size of the smoothing range matrix set by the setting unit 204. Performs noise removal processing on the color difference plane.

  Furthermore, the image processing apparatus 10 includes a first conversion unit 208, a second conversion unit 210, and a print execution unit 212 as optional components. The first conversion unit 208, the second conversion unit 210, and the print execution unit 212 are connected to each other together with the image source acquisition unit 200, the determination unit 202, the setting unit 204, and the noise removal processing execution unit 206 described above. It is connected to the.

  The first conversion unit 208 converts the image source image data acquired by the image source acquisition unit 200 into a YCbCr color space representation. Then, the noise removal processing execution unit 206 performs noise removal processing based on the image data converted into the YCbCr color space expression by the first conversion unit 208. For example, the first conversion unit 208 converts image data expressed in an RGB color space into an expression in a YCbCr color space.

  The second conversion unit 210 converts the image data from which noise has been removed by the noise removal processing execution unit 206 into image data expressed in an RGB color space.

  The print execution unit 212 executes printing based on the image data that has been subjected to noise removal processing by the noise removal processing execution unit 206.

  Thus, in the present invention, the image processing apparatus 10 can be realized by performing the above-described image noise removal processing of FIG. 2 by hardware.

FIG. 2 is a block diagram for explaining an example of the internal configuration of the image processing apparatus according to the present embodiment. The figure which shows the flowchart explaining an example of the image noise removal process performed with the image processing apparatus which concerns on this embodiment. The figure which shows an example of a structure of the smoothing range table classified by level which the image processing apparatus which concerns on this embodiment hold | maintains. The block diagram for demonstrating an example of a structure of the image processing apparatus at the time of implement | achieving image noise removal processing by hardware.

Explanation of symbols

10 Image processing device 20 CPU
22 ROM
24 Card interface 26 Communication interface 28 Screen interface 30 Device control unit 32 Internal bus 34 RAM
40 RAM
42 Print head 44 Carriage 46 Paper feed mechanism 48 Scanner 100 Card type external device 102 External device

Claims (6)

Image source acquisition means for acquiring an image source of a video source or a still image source;
Determining means for determining whether the image source acquired by the image source acquiring means is a moving image source or a still image source;
If the determination means determines that the source is a moving image source, the matrix size of the smoothing range used in the noise removal processing of the color difference plane is larger than the size of the matrix of the smoothing range used in the noise removal processing of the luminance plane. If it is determined that the image is a still image source by the determination means, the size of the matrix of the smoothing range used in the noise plane noise removal processing is set to the smoothing used in the color difference plane noise removal processing. Setting means for setting to be larger than the size of the matrix of the conversion range;
Luminance plane noise removal processing and chrominance plane noise removal processing are performed on image data based on the image source acquired by the image source acquisition unit with the size of the smoothing range matrix set by the setting unit. Noise removal processing execution means;
An image processing apparatus comprising: And further comprising first conversion means for converting the image source image data acquired by the image source acquisition means into a representation of a color space of YCbCr,
The noise removal processing execution means performs noise removal processing based on the image data converted into the representation of the YCbCr color space by the first conversion means.
The image processing apparatus according to claim 1.   The image processing apparatus according to claim 2, wherein the first conversion unit converts image data expressed in an RGB color space into an expression in a YCbCr color space.   4. The image processing according to claim 3, further comprising: a second conversion unit configured to convert the image data from which noise has been removed by the noise removal processing execution unit into image data expressed in an RGB color space. 5. apparatus.   The image according to any one of claims 1 to 4, further comprising: a print execution unit that executes printing based on the image data that has been subjected to noise removal processing by the noise removal processing execution unit. Processing equipment. Acquiring an image source of a video source or a still image source;
Determining whether the acquired image source is a video source or a still image source;
When it is determined that the image source is a moving image source, the matrix size of the smoothing range used in the noise removal processing of the color difference plane is larger than the matrix size of the smoothing range used in the noise removal processing of the luminance plane. If the image source is determined to be a still image source, the size of the smoothing range matrix used in the noise plane noise removal processing is set to the smoothing used in the color difference plane noise removal processing. A step of setting the size to be larger than the size of the matrix of the conversion range;
A step of performing a noise plane noise removal process and a color difference plane noise removal process on image data based on the acquired image source at the set smoothing range matrix size;
An image processing apparatus control method comprising:

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