JP2004336245A - Correction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cope with even dynamic variations such as temperature or secular variations by correcting the ununiformity between a plurality of imaging regions in real time. <P>SOLUTION: The correction apparatus is provided with: a plurality of level adjustment means 113, 114 for respectively independently adjusting a level of a plurality of imaging signals outputted from a plurality of output terminals; an output level detection means 116 for detecting an output level of a plurality of the level adjustment means; a focal degree discrimination means 117 for discriminating a focal degree of an imaging optical system of an imaging element; and a correction coefficient decision means 117 for deciding a correction coefficient to decrease a level difference of each imaging signal on the basis of a result of the detection of the output level detection means 116 and a result of the focal degree discrimination by the microcomputer 117, and the correction coefficient decision means 117 gives the decided correction coefficient to the level adjustment means 113, 114 so as to decreasingly adjust the level differences of each imaging signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a correction device, in particular, an imaging surface divided into a plurality of regions, an amplifier for amplifying an imaging signal in each region, and a solid-state imaging device having a plurality of imaging signal output terminals connected to the output. It is suitable for use in a correction device for correcting a signal.
[0002]
[Prior art]
In recent years, with the progress of digital signal processing technology and semiconductor technology, a consumer digital video standard for digitally recording moving picture signals of a standard television system, for example, NTSC system or PAL system, has been proposed. A digital video camera in which a device and an imaging device are integrated has been commercialized. Some of such digital video cameras have a still image recording function by utilizing the feature of digital recording.
[0003]
Further, there is also a digital camera equipped with a digital I / F for connection to a computer or the like, and having a function of taking a captured image into the computer. Further, an apparatus that includes a plurality of recording media and is capable of selecting a recording medium according to the purpose of use of an image has been put to practical use.
[0004]
In such an apparatus, when a recorded image is connected to a television and played back, the image size is determined by the digital video standard, for example, 720 × 480 pixels, and there is no problem. When transferring an image to another medium, a larger number of pixels may be required due to a problem in image quality.
[0005]
With the increase in the number of pixels of the image sensor, it is necessary to drive the image sensor at a higher frequency in order to read information of all pixels of the image sensor. There is a problem that causes an increase in power.
[0006]
Therefore, a method of increasing the data rate of imaging information while keeping the driving frequency of the imaging element low has been considered. As one of such methods, there is a method in which an imaging surface is divided into a plurality of regions, each region has an independent charge transfer unit, an amplifier, and an output terminal, and imaging signals are read out in parallel.
[0007]
FIG. 11 shows an example of an imaging device using the above-described imaging device. In FIG. 11, the imaging surface of the imaging device 1100 is divided into two regions on the left and right. 1101 and 1102 are photoelectric conversion and vertical transfer units; 1103 and 1104 are horizontal transfer units; 1105 and 1106 are amplifiers; 1107 and 1108 are output terminals. The use of the imaging device having such a structure has an advantage that imaging information having a data rate twice as high as the driving frequency of the imaging device can be obtained.
[0008]
On the other hand, a disadvantage of this method is that when an image is generated by combining two regions due to the non-uniformity of the characteristics of the amplifier and the external peripheral circuit in each region, a boundary line occurs due to a level difference between the regions. There is a problem that image quality deteriorates.
[0009]
As a method of reducing the image quality deterioration due to these non-uniformities, there is a method in which a black level and a standard white level of each area are measured in advance to obtain a correction coefficient, and the non-uniformity is corrected by the correction coefficient at the time of imaging. It is considered.
[0010]
FIG. 11 shows a configuration example of such a correction circuit. A subject image formed on the imaging device 1100 by an imaging optical system (not shown) is converted into an electric signal by the imaging device 1100, and the output terminal 1107 and the output terminal 1107 are provided in accordance with a driving pulse supplied from a driving timing generation circuit (not shown). Output from 1108.
[0011]
The two-system image signals obtained from the image sensor 1100 are subjected to analog signal processing by analog signal processing units 1109 and 1110, and then A / D converted, and supplied to black level correction circuits 1111 and 1112 and a black level difference detection circuit 1113. Is done. The black level difference detection circuit 1113 detects a black level difference from the two systems of image signals and calculates a correction coefficient.
[0012]
The correction coefficient is supplied to black level correction circuits 1111 and 1112, and the difference between the black levels is corrected based on the correction coefficient. The signal of the optical black pixel of the image sensor 1100 is used for detecting the difference between the black levels. The detection and the calculation of the correction value are performed only once at a predetermined time, and the obtained correction coefficient is stored in the memory 1120, so that the detection is not performed in the subsequent photographing, and the black level is determined by the correction coefficient stored in the memory 1120. The difference is corrected.
[0013]
Next, each signal is supplied to white level correction circuits 1114 and 1115 and a white level difference detection circuit 1116. The white level difference detection circuit 1114 detects a white level difference from the two systems of image signals and calculates a correction coefficient. The correction coefficient is supplied to black and white level correction circuits 1114 and 1115, and the difference between the white levels is corrected based on the correction coefficient.
[0014]
To detect a difference in white level, the image sensor 1100 is irradiated with uniform light so as to obtain a standard white level, and an image signal at that time is used. The detection and the calculation of the correction value are performed only once at a predetermined time, and the obtained correction coefficient is stored in the memory 1121 so that the detection is not performed in the subsequent photographing and the correction coefficient stored in the memory 1121 is used. The correction of the white level difference is performed.
[0015]
The signal subjected to the white level correction is subjected to γ correction processing, contour correction processing, color correction processing, and the like in a camera signal processing circuit 1118 after the left and right images are synthesized as one image by a screen synthesis circuit 1117. , And are output from an output terminal 1119 as a luminance signal and a color difference signal.
[0016]
[Problems to be solved by the invention]
However, in the above-described conventional example, the correction coefficient is calculated only under predetermined conditions, such as when a standard white image is captured, and thus there is a problem that real-time properties are lacking. For this reason, it is not possible to cope with dynamic fluctuations such as temperature fluctuations or temporal fluctuations, or fluctuations in the degree of focus of the imaging optical system, and it may not be possible to sufficiently correct non-uniformity between regions. there were.
[0017]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made in view of the above-described circumstances. It is an object of the present invention to be able to cope with dynamic fluctuations.
[0018]
[Means for Solving the Problems]
The correction device of the present invention is a correction device that corrects a plurality of imaging signals from a plurality of output units of an imaging device,
Level adjusting means for adjusting the levels of the plurality of imaging signals; and a level adjusting means for adjusting a level difference between the plurality of imaging signals based on a degree of focus of an imaging optical system that forms a subject image on an imaging device. Correction coefficient determining means for determining a correction coefficient,
The correction coefficient determined by the correction coefficient determination means is supplied to the level adjustment means, and adjustment is performed so that the level difference between the image pickup signals is reduced.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment in which the correction device of the present invention is applied to an imaging device will be described with reference to the accompanying drawings.
(First Embodiment)
FIG. 1 is a diagram schematically showing an embodiment in which the present invention is applied to a single-panel video camera.
In FIG. 1, reference numeral 100 denotes a CCD area sensor in which an imaging area is divided into two, each having an output terminal; 101, a photoelectric conversion unit and a vertical transfer unit; and 103 and 104, a horizontal transfer unit; It is divided into two parts in the horizontal direction.
[0020]
Output amplifiers 105 and 106 amplify signal charges, and 107 and 108 are output terminals for imaging signals. Reference numerals 109 and 110 denote analog front ends for performing correlated double samples and AD conversion. 111 and 112 are black level detecting and correcting means, 113 and 114 are gain adjusting means for adjusting gain, and 115 is a screen synthesizing means for synthesizing two systems of image signals to generate one image.
[0021]
Reference numeral 116 denotes a step evaluation value generating means for detecting non-uniformity between the two systems, 117 a microcomputer for controlling the system, 118 a camera signal processing means, 119 an output terminal, and 120 a rewritable nonvolatile memory. A memory 121 is an imaging optical system.
[0022]
Next, the operation of the video camera of the present embodiment having the above configuration will be described.
The optical system 121 is for forming a subject image on the CCD 100, and the microcomputer 117 controls focus and aperture.
The subject image formed on the CCD 100 by the optical system 121 is converted into an electric signal by a photoelectric conversion unit 101, and then divided into two systems by horizontal transfer paths 103 and 104 and supplied to output amplifiers 105 and 106. Is done.
In the present embodiment and the embodiments described later, a correction device for detecting and correcting non-uniformity between two systems is configured by the gain adjustment units 113 and 114, the step evaluation value generation unit 116, and the microcomputer 117. are doing.
[0023]
The signal charges are amplified to a predetermined level by the output amplifiers 105 and 106, and output from the first output terminal 107 and the second output terminal 108. Hereinafter, the image signal obtained from the first output terminal 107 is referred to as a left channel signal, and the image signal obtained from the second output terminal 108 is referred to as a right channel signal.
[0024]
The left and right imaging signals are subjected to correlated double sampling processing and A / D conversion by analog front ends 109 and 110, and then supplied to black level detection and correction units 111 and 112. The black level detection and correction means 111 and 112 use the dummy signal portion or the optical black signal portion of the image pickup signal so that the black levels of the two systems of image pickup signals coincide with the digital code "0". Correction is performed. Thereby, the error of the offset component between the two systems is removed.
[0025]
The signals whose black levels have been corrected are subjected to gain adjustment by gain adjusting means 113 and 114. The gain applied at the time of gain adjustment is supplied from the microcomputer 117. In the conventional imaging apparatus, the gain of the signal amount in a low illuminance environment is increased by an analog circuit. However, in the imaging apparatus that handles two types of imaging signals as in the present embodiment, the gain adjustment by the analog circuit is performed. Can be a factor of non-uniformity between the two systems. Therefore, in the present embodiment, the gain adjustment is performed by digital operation using the gain adjustment means 113 and 114, thereby eliminating the influence of circuit variation, temporal variation, and temperature variation.
[0026]
In addition, not only gain adjustment for image brightness but also correction of gain error between the two systems is performed here. Generally, the difference in gain between the two systems depends on the magnitude of the output level of the CCD area sensor 100.
[0027]
FIG. 3 is a characteristic diagram showing an example of an output level between two systems and a gain difference between channels. In FIG. 3, the horizontal axis represents the output level of the left channel of the CCD 100, and the vertical axis represents the ratio of the input signal (left channel) of the gain adjustment unit 114 to the signal of the input signal (right channel) of the gain adjustment unit 113, that is, 2 It represents the gain difference of the signal level between the systems.
[0028]
For example, assuming that the left channel output level of the CCD 100 is L0 and the right channel output level is L0right when an image of a subject of a certain brightness is captured, the gain difference E0 at this time is given by the following equation (1).
E0 = L0right / L0 (1)
As shown in this figure, since the relationship between the signal level and the gain difference is not constant, the correction amount of the gain is not a fixed value, and the correction amount needs to be changed according to the gain-up amount.
[0030]
In this embodiment, the reference level Lref is set for the signal after gain adjustment, and the level difference between the two systems is always 0 at the reference level Lref regardless of the gain-up amount, that is, the signal of each channel is set to the reference level Lref. Gain correction is performed so that they match. As the level of the reference level Lref, a gray level of about 75% is selected after the γ correction for the reference white.
[0031]
For example, when the left channel output level of the CCD 100 is L0 and the gain is increased so that the output level of the gain adjustment unit 114 becomes the reference level Lref, the gain A0 given to the left channel gain adjustment unit 114 can be expressed by the following equation. .
A0 = reference level Lref / L0 (2)
Further, at this time, the gain A0right given to the gain adjustment means 113 of the right channel can be expressed by the following equation, where the gain correction amount is C0.
A0right = A0 × C0 (3) and C0 is obtained by the following equation.
C0 = 1.0 / E0 (4)
Similarly, when the output level of the left channel of the CCD 100 is L1, the gain correction amount C1 when the output level of the gain adjustment unit 114 is a gain-up amount that becomes the reference level Lref is obtained by the following equation.
C1 = 1.0 / E1 (5)
FIG. 4 shows a characteristic example of the gain correction amount with respect to the gain increase amount. This correction characteristic differs for each component of the CCD 100 or the analog front ends 109 and 110.
[0035]
Next, measurement of the gain correction characteristic will be described.
The step evaluation value generation means 116 calculates an evaluation value of the screen step based on the pixel values in the rectangular area specified near the boundary of the divided area, and outputs the evaluation value to the microcomputer 117.
[0036]
FIG. 2 shows an example of a rectangular area in the screen. As shown in FIG. 2, rectangular regions 203 and 204 are set near the boundary between the two divided regions 201 and 202, and the pixel values in these regions are used for evaluating a screen step.
[0037]
The CCD 100 has an on-chip color filter attached to a pixel portion in order to capture a color image on a single plate. The on-chip color filters are arranged, for example, as shown at 205 in FIG. The step evaluation value generation means 116 selects a pixel value of one color among them, calculates an average value in the area, and uses this as an evaluation value of the screen step.
[0038]
At the time of measuring the gain correction characteristic, an image of a subject having a uniform brightness is taken, and the microcomputer 117 sets the same gain multiplier to the gain adjustment means 113 and 114 to perform the measurement. The average level of the pixels in one rectangular area 203 is set to the level of the left channel, and the average level of the pixels in the other rectangular area 204 is set to the level of the right channel and output to the microcomputer 117.
[0039]
The microcomputer 117 calculates the gain correction amount of the right channel based on the level of the left channel as described above. By performing such a measurement at predetermined intervals at the output level of the CCD 100, a gain correction characteristic is generated.
[0040]
The microcomputer 117 stores the generated gain correction characteristic in a rewritable non-volatile memory 120 such as an EEPROM (Electrically Erasable Programmable Read Only Memory). The generation of the gain correction characteristic is executed, for example, at the time of factory adjustment. Therefore, it cannot respond to dynamic fluctuations such as temporal fluctuations and temperature fluctuations, and the gain difference remains as an error.
[0041]
Next, correction of the residual gain error at the time of general photographing will be described.
FIG. 5 is a diagram showing a configuration in which a correction coefficient is determined based on the degree of focus of an imaging optical system that forms an object image on an image sensor, and the determined correction coefficient is provided to a gain adjustment unit to provide different output terminals of a CCD area sensor. 1 shows a configuration of a block for correcting a residual gain error, which is executed by a microcomputer 117 which is a correction coefficient determining means for performing adjustment so as to reduce a level difference between image pickup signals output from the microcomputer. The signals A, B, C, and D in FIG. 5 correspond to the signals A, B, C, and D in FIG. 1, where reference symbol A denotes a left channel step evaluation value, reference sign B denotes a right channel step evaluation value, Symbol C is a left channel gain adjustment value, and symbol D is a right channel gain adjustment value.
[0042]
The left channel step evaluation value A and the right channel step evaluation value B input to the microcomputer 117 are input to the gain error calculation means 501, and the gain error E is obtained. The gain error E is obtained by the following equation.
E = B / A Expression (6)
The gain error amount E obtained by the gain error calculating means 501 is simply a ratio of pixel levels, and is affected not only by non-uniformity between channels but also by a level difference of the subject itself. Therefore, in order to perform correct gain error correction, it is necessary to eliminate a subject-dependent level difference component. In the present embodiment, the subject-dependent level difference component is eliminated by the limiter unit 502 and the integration unit 503.
[0044]
FIG. 6 shows the input / output characteristics of the limiter unit 502. The origin in FIG. 6 represents a point where limiter input = limiter output = 1.0. Since there is a level ratio between channels, the value when there is no gain error is 1.0.
[0045]
As shown in FIG. 6, when the level difference ratio exceeds the threshold value TH, the limiter output becomes 1.0. The threshold value TH is determined in association with the residual gain error amount. As a result of this processing, a level difference that is large is regarded as a subject-dependent level difference and is eliminated.
[0046]
FIG. 7 shows the internal configuration of the integration means 503. After subtracting the input signal X (0) from the signal Y (-1) delayed by a predetermined time in the subtraction means 701, the coefficient k is multiplied by the coefficient unit 702. The output of the coefficient unit 702 is added to the delay signal by the adding means 703 to become an output, while being supplied to the delay means 704. When the output signal is expressed as Y (0), the following expression is obtained.
Y (0) = kX (0) + (1−k) Y (−1) (0 <k <1) Expression (7)
The delay time is a time equal to the vertical scanning period of the CCD. By this processing, an average value of the error amounts for the past 1 / k frames is obtained. Normally, the subject is not fixed for a long time in the angle of view, so by taking an average over a plurality of frames, the level difference component depending on the subject is canceled out and eliminated.
[0048]
The information on the degree of focus is input to the coefficient unit 701, whereby the coefficient k given to the coefficient unit 702 is controlled. The coefficient control will be described later.
[0049]
Through the above processing, the level difference due to the subject is eliminated, and the gain error due to the non-uniformity between the channels is extracted. Next, the gain error amount is multiplied by a coefficient by the correction amount control unit 504. This coefficient corresponds to the feedback gain of the gain error correction loop. When the gain is large, the correction capability is high, but it becomes unstable against disturbances such as erroneous detection, and when the gain is small, it is stable against disturbances, but the correction capability is low.
[0050]
The output of the correction amount control unit 504 is supplied to a gain correction amount calculation unit 506. The output of the gain correction characteristic table 505 is also supplied to the gain correction amount calculation means 506. The gain correction characteristic table 505 is a table in which the gain correction characteristics described above are tabulated, and as shown in FIG. 4, a gain correction amount is obtained corresponding to the gain increase amount.
[0051]
In the gain correction amount calculating means 506, the gain adjustment value for the right channel is actually calculated by multiplying the two input signals by the gain up amount. Then, the gain adjustment value thus calculated is supplied to the gain adjustment means 113 shown in FIG. The gain increasing amount itself is supplied to the gain adjusting means 114.
[0052]
The signal after the gain adjustment is supplied to the screen synthesizing means 115 and the step evaluation value generating means 116. The screen synthesizing unit 115 synthesizes the signals of the two systems and outputs them to the camera signal processing circuit 118 and the AF evaluation value generating unit 122 as an image of one screen. The camera signal processing circuit 118 performs signal processing such as γ correction, color correction, and contour correction, and outputs the image signal from a terminal 119.
[0053]
On the other hand, the AF evaluation value generation means 122 generates an evaluation value required for the focus degree determination by a method such as extracting an edge component of the screen and outputs the evaluation value to the microcomputer 117. The microcomputer 117 determines the degree of focus using this evaluation value, and controls the imaging optical system 121 based on the result, thereby implementing an autofocus operation. Note that the method of generating the AF evaluation value and the method of determining the degree of focus are not essential in the present invention, and will not be described in detail.
[0054]
As described above, when measuring the level difference between the left and right screens from a general captured image, a level change of the subject itself may be cited as a disturbance element. The level change of the subject itself changes depending on the degree of focusing, and becomes maximum in the focused state. In the present embodiment, using this property, variable control of the characteristics of the correction loop is performed according to the degree of focusing.
[0055]
FIG. 10 shows the characteristics of coefficient control with respect to the degree of focus, and shows the operation of the coefficient control means in FIG. In FIG. 10, the horizontal axis indicates the degree of focusing, and the degree of focusing increases as going to the right. The vertical axis represents the output coefficient. With respect to the output coefficient at the time of focusing, the coefficient value increases as the degree of focusing decreases.
[0056]
By such control, the number of frames to be averaged is increased at the time of focusing where the level difference of the subject itself appears to be the largest in the image pickup signal, and is stable against disturbance (= the level difference of the subject itself). Is performed. On the other hand, when the subject is out of focus, the level difference of the subject itself becomes small, and thus control is performed with emphasis on responsiveness rather than loop stability.
[0057]
(Second embodiment)
FIG. 8 is a diagram schematically showing an embodiment of the image recording / reproducing apparatus of the present invention. FIG. 9 is a flowchart for explaining the operation of the recording / reproducing apparatus according to the second embodiment of the present invention. The operation shown in the flowchart of FIG. 9 is performed by the microcomputer 817 in FIG.
[0058]
In FIG. 8, the flow of signal processing from the image sensor 800 to the camera signal processing means 818 is the same as in the first embodiment described above, and a description thereof will be omitted.
[0059]
The image signal processed by the camera signal processing unit 818 is supplied to the recording / reproducing unit 819. The recording / reproducing means 819 performs recording on a recording medium (not shown) and reproduction from the recording medium. An output image signal of the recording / reproducing means 819 is output to the outside through an output terminal 823.
[0060]
The recording operation control switch 824 is connected to the microcomputer 817, and the user of the image recording / reproducing apparatus can control the start and stop of the recording operation by pressing the switch 824.
[0061]
Next, the operation of the recording / reproducing apparatus of the present embodiment will be described with reference to the flowchart of FIG.
As shown in FIG. 9, when the processing is started in step S901, next, in step S902, the level difference between the left channel and the right channel is calculated, and the level difference is larger than a predetermined specified value A. Then, it is determined whether or not the recording / reproducing means 819 is in a recording stop state.
[0062]
As a result of this determination, if it is, the process proceeds to step S903, and if not, the conditional branch of terminating is executed.
In the next step S903, control is performed so that the imaging optical system is largely deviated from the in-focus position. After that, the process advances to step S904 to control the gain correction control loop to operate in the high-speed pull-in mode.
[0063]
The high-speed pull-in mode means that the value of the feedback gain applied by the correction amount control unit 504 in FIG. 5 is made larger than usual and / or the number of frames averaged by the integration unit 503 is reduced. By doing so, it refers to an operation state in which the response of gain correction is improved.
[0064]
Next, in step S925, the level difference between the left and right channels is evaluated. If the level difference is smaller than the reference value B, or if the recording operation has been started, the process proceeds to step S926. Keep the mode state. By setting the reference value B at this time to a value smaller than the above-described reference value A, a hysteresis characteristic is provided.
[0065]
In step S906, control is performed so that the control loop for gain correction operates in the normal mode. Subsequently, in step S907, the focus control is returned to the normal auto focus mode, and a series of operations ends. This operation is repeatedly executed at a predetermined cycle.
[0066]
By this control, the detected level difference between the left and right channels becomes large, and if it becomes difficult to determine whether the level difference is inherent to the subject itself, by keeping the imaging optical system in a blurred state, It is possible to easily determine the level difference of the device itself and the level difference caused by the non-uniformity between the left and right channels.
[0067]
Furthermore, by increasing the response of the gain correction loop so that the state is completed in a short time, the blurred state does not continue for a long time.
By controlling this operation not to be performed during the recording operation, it is possible to prevent the user from missing a shooting opportunity.
[0068]
(Another embodiment of the present invention)
The present invention may be applied to a system including a plurality of devices or an apparatus including one device.
[0069]
Further, a transmission medium such as the Internet or the like is transmitted to a computer in an apparatus or a system connected to the various devices so as to operate various devices so as to realize the functions of the above-described embodiments. Also, the present invention provides a program code of software for realizing the functions of the above-described embodiment through the above-described embodiment, and executes the above-described various devices according to a program stored in a computer (CPU or MPU) of the system or the apparatus. Are included in the scope of the present invention.
[0070]
In this case, the program code itself of the software implements the functions of the above-described embodiment, and the program code itself and a unit for supplying the program code to the computer, for example, the program code is stored. The storage medium described constitutes the present invention. As a storage medium for storing such a program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0071]
When the computer executes the supplied program code, not only the functions described in the above-described embodiments are realized, but also the OS (Operating System) running on the computer or another program. It goes without saying that such a program code is also included in the embodiment of the present invention when the functions described in the above embodiment are realized in cooperation with application software or the like.
[0072]
Further, after the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, a CPU provided in the function expansion board or the function expansion unit based on the instruction of the program code. The present invention also includes a case in which the functions of the above-described embodiments are implemented by performing some or all of the actual processing.
[0073]
Examples of embodiments of the present invention are listed below.
[Embodiment 1] A correction device for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
Level adjusting means for adjusting the levels of the plurality of imaging signals; and a level adjusting means for adjusting a level difference between the plurality of imaging signals based on a degree of focus of an imaging optical system that forms a subject image on an imaging device. Correction coefficient determining means for determining a correction coefficient,
A correction device, wherein the correction coefficient determined by the correction coefficient determination means is supplied to the level adjustment means so as to perform adjustment so that the level difference between the respective imaging signals is reduced.
[Embodiment 2] An output level detection unit that detects output levels of the plurality of imaging signals,
The correction apparatus according to claim 1, wherein the correction coefficient determination unit determines a correction coefficient based on the level detection result such that a level difference between the plurality of imaging signals is reduced.
[0074]
[Embodiment 3] The output level detecting means includes an area selecting means for selecting a predetermined area from among the plurality of imaging signals, and an average for calculating an average level in the area selected by the selected area selecting means. The correction device according to the second embodiment, further comprising a level calculation unit.
[0075]
[Embodiment 4] The output level detection unit includes a color signal selection unit that selects a predetermined color signal from the plurality of imaging signals, and a detection result is obtained by using the color signal selected by the color signal selection unit. The correction device according to the second or third embodiment, wherein the correction device generates
[0076]
[Embodiment 5] The correction coefficient determining unit calculates a gain error between image signals from a plurality of detection results, and a subject-dependent level difference component in the plurality of image signals. Threshold setting means for setting the threshold value, and when a signal of the gain error calculation means is input, a reference value is output when the gain error exceeds the threshold value, and the gain error Non-linear processing means for outputting the input gain error as it is when it does not exceed, and a correction coefficient is determined based on an output signal of the non-linear processing means. The correction device according to the paragraph.
[0077]
[Embodiment 6] The correction coefficient determination unit includes an evaluation value generation unit that generates an evaluation value from a detection result of the output level detection unit, and an evaluation value generated by the evaluation value generation unit averaged over a plurality of frames. Evaluation value averaging means, and a frame number setting means for setting the number of frames to be averaged by the evaluation value averaging means,
The correction apparatus according to any one of embodiments 2 to 5, wherein a correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number setting unit.
[0078]
[Embodiment 7] Frame number control means for variably controlling the number of frames to be averaged by the evaluation value averaging means in accordance with the degree of focus of an imaging optical system for forming a subject image on the image sensor. The correction device according to claim 6, characterized in that:
[0079]
[Eighth Embodiment] In the correction device, when the correction coefficient determination unit is operating in a first operation mode, if the level difference between the imaging signals becomes larger than a first specified value, the image formation is performed. The optical system is controlled so as to be out of focus, and control is performed to shift the operation mode of the correction coefficient determination means to the second operation mode, so that the level difference between the imaging signals is smaller than the second specified value. When the value becomes smaller, the operation mode of the correction coefficient determination unit is shifted to the first mode, and the imaging operation control unit controls the imaging optical system to be in focus. The correction device according to any one of Embodiments 2 to 7, wherein
[0080]
[Embodiment 9] The correction apparatus according to Embodiment 8, wherein the imaging control operation by the imaging operation control is repeatedly executed at predetermined intervals.
[0081]
[Embodiment 10] The correction apparatus according to embodiment 8 or 9, wherein the second prescribed value is smaller than the first prescribed value.
[0082]
[Embodiment 11] The correction apparatus according to any one of Embodiments 8 to 10, wherein the first operation mode of the correction coefficient determination unit has lower responsiveness than the second operation mode.
[0083]
[Embodiment 12] An image recording / reproducing apparatus that uses an image sensor that outputs a plurality of image signals and records an image signal captured by the image sensor on a recording medium,
Level adjustment means for independently adjusting the levels of the plurality of imaging signals, output level detection means for detecting the output levels of the plurality of level adjustment means, and focus degree determination for determining the focus degree of the imaging optical system Means, and a correction coefficient determining means for determining a correction coefficient such that the levels of the respective imaging signals become equal based on the output level detection result by the output level detecting means and the focus degree determination result by the focus degree determining means. Prepare,
An image recording / reproducing apparatus, wherein the correction coefficient is given to the level adjusting means so as to perform adjustment so that the levels of the respective imaging signals become equal.
[0084]
[Thirteenth Embodiment] When the correction coefficient determination unit is operating in the first operation mode, the level difference between the imaging signals becomes larger than a first specified value, and the imaging signals are stored in a recording medium. When the recording unit for recording is in the recording stop state, the image forming optical system that forms the subject image on the image sensor is controlled so as to be out of focus, and the operation mode of the correction coefficient determination unit is changed to the second mode. 2 is performed, and when the level difference between the imaging signals is smaller than a second specified value or when the recording unit is in a recording operation state, the correction coefficient determining unit The image recording / reproducing apparatus according to embodiment 11, further comprising: an imaging operation control unit configured to shift the operation mode to the first mode and to control the imaging optical system to be in a focused state.
[0085]
[Embodiment 14] The image recording / reproducing apparatus according to embodiment 12, wherein the imaging operation control means repeatedly executes the control operation at predetermined intervals.
[0086]
[Embodiment 15] The image recording / reproducing apparatus according to Embodiment 12, wherein the second prescribed value is smaller than the first prescribed value.
[0087]
[Embodiment 16] The image recording / reproduction according to any one of Embodiments 12 to 14, wherein the first operation mode of the correction coefficient determination unit has lower responsiveness than the second operation mode. apparatus.
[0088]
[Embodiment 17] A correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
A level adjustment process for adjusting the levels of the plurality of imaging signals, and a level difference between the plurality of imaging signals based on a focus degree of an imaging optical system that forms a subject image on an imaging device. Correction coefficient determination processing for determining a correction coefficient,
A correction method, wherein a correction coefficient determined by the correction coefficient determination processing is applied to the level adjustment processing so as to perform adjustment so as to reduce a level difference between image pickup signals.
(Eighteenth Embodiment) An output level detection process for detecting output levels of the plurality of imaging signals,
18. The correction method according to claim 17, wherein the correction coefficient determination processing determines a correction coefficient based on the level detection result such that a level difference between the plurality of imaging signals is reduced.
[0089]
[Embodiment 19] The output level detection processing includes an area selection processing for selecting a predetermined area from the plurality of imaging signals, and an average for calculating an average level in the area selected by the selection area selection processing. The correction method according to embodiment 18, comprising a level calculation process.
[0090]
[Embodiment 20] The output level detection process includes a color signal selection process of selecting a predetermined color signal from the plurality of imaging signals, and the output level detection process is performed using the color signal selected by the color signal selection process. 20. The correction method according to embodiment 18 or 19, wherein a result is generated.
[0091]
[Embodiment 21] The correction coefficient determination process is a process of calculating a gain error between respective imaging signals from a plurality of detection results, and eliminating a subject-dependent level difference component in the plurality of imaging signals. A threshold setting process for setting a threshold value, and when a signal of the gain error calculation process is input, a reference value is output when the gain error exceeds the threshold value, and the gain error If not exceeded, the input gain error is output as it is,
The correction method according to any one of embodiments 18 to 20, wherein a correction coefficient is determined based on an output signal of the non-linear processing.
[0092]
[Embodiment 22] The correction coefficient determination process includes an evaluation value generation process of generating an evaluation value from a detection result of the output level detection process, and an evaluation value generated by the evaluation value generation process being averaged over a plurality of frames. Evaluation value averaging process, and a frame number setting process of setting the number of frames to be averaged by the evaluation value averaging process,
The correction method according to any one of embodiments 18 to 21, wherein a correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number setting process.
[0093]
[Embodiment 23] There is provided a frame number control process for variably controlling the number of frames to be averaged in the evaluation value averaging process according to the degree of focus of an imaging optical system that forms a subject image on the image sensor. 23. The correction method according to claim 22, characterized in that:
[0094]
[Embodiment 24] In the correction method, when the level difference between the imaging signals becomes larger than a first specified value while the correction coefficient determination process is operating in the first operation mode, the image formation is performed. In addition to controlling the optical system to be in an out-of-focus state, control is performed to shift the operation mode of the correction coefficient determination process to the second operation mode, and the level difference between the imaging signals is set to be smaller than the second specified value. In the case where the image size has also become smaller, the operation mode of the correction coefficient determination process is shifted to the first mode, and an imaging operation control process for controlling the imaging optical system to be in a focused state is provided. The correction method according to any one of embodiments 18 to 23, wherein
[0095]
Twenty-fifth Embodiment A correction method according to the twenty-fourth embodiment, wherein the imaging control operation by the imaging operation control is repeatedly executed at predetermined intervals.
[0096]
[Embodiment 26] The correction method according to Embodiment 24 or 25, wherein the second specified value is smaller than the first specified value.
[0097]
Embodiment 27 The correction method according to any one of Embodiments 24 to 26, wherein the first operation mode of the correction coefficient determination process has lower responsiveness than the second operation mode.
[0098]
[Embodiment 28] A program for causing a computer to execute a correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
A level adjustment process for adjusting the levels of the plurality of imaging signals, and a level difference between the plurality of imaging signals based on a focus degree of an imaging optical system that forms a subject image on an imaging device. Correction coefficient determination processing for determining a correction coefficient,
A computer program for causing a computer to execute a process of giving a correction coefficient determined by the correction coefficient determination process to the level adjustment process and performing adjustment so as to reduce a level difference between image pickup signals.
[0099]
[Embodiment 29] A computer-readable recording medium on which the computer program according to Embodiment 28 is recorded.
[0100]
【The invention's effect】
As described above, according to the present invention, it is possible to correct non-uniformity among a plurality of imaging regions in real time, and furthermore, to perform adaptive control according to the degree of focusing of an imaging optical system. Can be performed, the level difference component depending on the subject can be effectively removed, and even when a dynamic fluctuation occurs, the step appearing in the image can be apparently eliminated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention and showing a configuration of a first embodiment in which a correction device of the present invention is applied to a video camera.
FIG. 2 is a diagram illustrating a rectangular area at a boundary of a divided screen.
FIG. 3 is a characteristic diagram showing a CCD output level and a gain difference between channels.
FIG. 4 is a diagram showing a gain correction characteristic with respect to a gain-up amount.
FIG. 5 is a block diagram illustrating a configuration example of a unit that executes a procedure of calculating a gain adjustment value according to the first embodiment.
FIG. 6 is a diagram illustrating input / output characteristics of a limiter according to the first embodiment.
FIG. 7 is a block diagram illustrating a configuration example of an integration unit according to the first embodiment.
FIG. 8 is a block diagram showing a second embodiment in which the correction device of the present invention is applied to a video camera, and showing a configuration example of a recording / reproducing device.
FIG. 9 is a flowchart illustrating an operation of the recording / reproducing apparatus according to the second embodiment.
FIG. 10 is a diagram illustrating coefficient control characteristics according to the second embodiment, and illustrating characteristics of coefficient control with respect to the degree of focus.
FIG. 11 is a block diagram illustrating an example of a conventional imaging apparatus.
[Explanation of symbols]
Reference Signs List 100 CCD area sensor 101 Photoelectric conversion unit and vertical transfer unit 103, 104 Horizontal transfer unit 105, 106 Output amplifier 107, 108 Image signal output terminal 109, 110 Analog front end 111, 112 Black level detection and correction means 113, 114 Gain adjusting means 115 screen synthesizing means 116 step evaluation value generating means 117 microcomputer for controlling the system 118 camera signal processing means 119 output terminal 120 rewritable nonvolatile memory 121 thermometer 122 AF evaluation value generating means

Claims (1)

A correction device for correcting a plurality of imaging signals from a plurality of output units of the imaging device,
Level adjusting means for adjusting the levels of the plurality of imaging signals; and a level adjusting means for adjusting a level difference between the plurality of imaging signals based on a degree of focus of an imaging optical system that forms a subject image on an imaging device. Correction coefficient determining means for determining a correction coefficient,
A correction device, wherein the correction coefficient determined by the correction coefficient determination means is supplied to the level adjustment means so as to perform adjustment so that the level difference between the respective imaging signals is reduced.

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