JP4297651B2 - Image signal processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image signal processing apparatus that detects and corrects noise pixels included in an image signal.
[0002]
[Prior art]
An image signal generated by an image sensor such as an image sensor may include random noise generated at random or fixed pattern noise such as pixel defects.
[0003]
Noise called a pixel defect appears as a white spot or a black spot on the reproduction screen due to defective pixels among a plurality of light receiving pixels arranged in the image sensor. Some conventional techniques for correcting this pixel defect use a characteristic that a pixel defect occurs at a fixed position over a plurality of screens. Specifically, since the pixel defect occurs at a certain position, random noise can be removed and the pixel defect can be detected by performing time integration over a plurality of screens. This time integration can be performed by accumulating the image signals at the same position on the image using a memory. Further, once a pixel defect is detected, the position can be stored in the memory. In subsequent imaging, it is possible to automatically correct the image signal corresponding to the pixel defect position stored in the memory without performing pixel defect detection processing. As a pixel defect correction method, there is a method of interpolating image signals of peripheral pixels at a pixel defect position. That is, the interpolation value of the peripheral pixel is used as the image signal at the pixel defect position.
[0004]
On the other hand, the pixel position where random noise occurs changes irregularly. Therefore, when time integration is performed, an image signal including noise and an image signal not including noise are averaged, and random noise cannot be detected. Further, it is not possible to store the generated position and automatically correct it. Random noise increases when the gain (gain) of the image signal is increased or the exposure time of the imaging device is increased. In other words, in the image signal obtained under imaging conditions with low illuminance, the contribution of electrons generated in the image sensor due to thermal noise, etc. is relatively small because of the small amount of electrons generated by photoelectric conversion of incident light from the subject. Become bigger. Here, for example, the contour enhancement process deteriorates the S / N ratio of the image quality. Conventionally, image signal processing that affects the S / N ratio is controlled in accordance with the gain of the image signal and the like, thereby reducing image quality degradation due to random noise. For example, when the gain is increased, the noise feeling of the image is reduced by reducing the amplitude of the aperture signal to weaken the contour enhancement. The conventional image signal correction process for such random noise is not a process in units of pixels such as an interpolation process for pixel defects, but a process that is uniformly applied to the entire screen.
[0005]
[Problems to be solved by the invention]
As described above, the conventional correction processing for random noise has an effect on pixels other than the noise pixels, and thus has a problem that it cannot be applied with sufficient strength to obtain a sufficient effect.
[0006]
Similarly to the correction for pixel defects, performing an interpolation process that replaces an image signal of a pixel in which random noise has occurred with an image signal obtained by interpolating the surrounding pixels, the frequency of occurrence of random noise is less than that of pixel defects. Since it is much higher, the resolution of the image is significantly reduced, which is generally not preferable.
[0007]
On the other hand, when random noise is significant as in low-illumination imaging conditions, it may be desirable to suppress the noise sensation at the expense of some resolution. However, conventionally, random noise and pixel defects are corrected by a separate circuit configuration and separate processing, and interpolation processing cannot be applied to random noise by switching processing according to imaging conditions and the like. For example, in a conventional pixel defect correction circuit that performs time integration, random noise cannot be detected as described above, and interpolation processing of the random noise cannot be performed.
[0008]
The present invention has been made to solve the above problems, and an object of the present invention is to provide an image signal processing apparatus capable of suitably correcting random noise included in an image signal and obtaining an image of good image quality. It is another object of the present invention to provide an image signal processing apparatus that can flexibly correct random noise and pixel defects according to imaging conditions and the like.
[0009]
[Means for Solving the Problems]
The image signal processing apparatus according to the present invention, when an image signal for displaying a reproduced image in one screen unit is a pixel defect that does not include an image component among a plurality of pixels constituting the screen. An image signal processing device that performs interpolation processing and performs correction processing when a noise pixel includes a noise component exceeding a predetermined level, and is a maximum level and a minimum level of image signals of a plurality of peripheral pixels adjacent to a target pixel And a second reference range that includes the first reference range and is wider than the first reference range is set, and the signal level of the target pixel is set to the first reference range. Determination that the target pixel is determined to be the noise pixel when the target pixel is outside the first reference range, and that the target pixel is determined to be the pixel defect when the signal level of the target pixel is outside the second reference range A correction circuit that performs a level correction process on the noise pixel based on a determination result of the path, the determination circuit, and a plurality of peripheral pixels for the pixel defect based on the determination result of the determination circuit. An interpolation circuit that performs an interpolation process based on the signal level.
[0010]
According to the present invention, the determination circuit compares the original image signal between the target pixel and its peripheral pixels to determine whether the target pixel is a pixel defect or a noise pixel. Since the determination circuit performs determination based on comparison with surrounding pixels without basically performing time integration on the original image signal, it is possible to detect random noise. The image signal processing circuit performs a predetermined intended signal processing on the original image signal of normal pixels to generate a target image signal. On the other hand, interpolation processing is performed for pixel defects, and level correction processing is performed for noise pixels. Here, the level correction processing for the noise pixel can remove and mitigate the noise component included in the original image signal of the noise pixel. That is, the image signal processing circuit performs noise pixel level correction processing in units of pixels. Specifically, the determination circuit is set with a first reference range and a second reference range that includes the first reference range and is wider. These reference ranges are set for each target pixel based on the image signal of the surrounding pixels. When the image signal of the target pixel is within the first reference range, the difference in the image signal from the surrounding pixels is relatively small, and when the image signal of the target pixel is outside the second reference range, the image signal of the target pixel is relatively When the image signal of the target pixel is outside the first reference range and inside the second reference range, the difference from the image signal of the peripheral pixel is moderate. It is. The determination circuit determines a target pixel having a large difference from surrounding pixels as a pixel defect, and determines a target pixel having a medium difference as a noise pixel. In general, the larger the signal level difference between the target pixel and the surrounding pixels, the lower the frequency of occurrence of the event, so that pixel defects with low frequency of occurrence can be suitably corrected by interpolation, while noise pixels with high frequency of occurrence are corrected. On the other hand, by performing level correction processing that does not perform interpolation, noise pixels can be made inconspicuous on the image while suppressing deterioration in resolution.
[0011]
In a preferred aspect of the present invention, the determination circuit uses the range from the maximum level to the minimum level of the image signals of the plurality of peripheral pixels as the first reference range, and the image signals of the plurality of peripheral pixels An image signal having a range from a level obtained by adding a difference between the maximum level and the minimum level to an average level to a level obtained by subtracting a difference between the maximum level and the minimum level from the average level as the second reference range. It is a processing device.
[0012]
A preferred aspect of the present invention further includes a register for storing a predetermined offset value, and the determination circuit defines a range from a maximum level to a minimum level of the image signals of the plurality of peripheral pixels as the first reference range. In addition, the image signal processing apparatus uses a range from a level obtained by adding the predetermined offset value to the maximum level to a level obtained by subtracting the predetermined offset value from the maximum level as the second reference range.
[0013]
According to a preferred aspect of the present invention, the image signal processing further includes a color signal generation circuit that generates a color difference signal from the input image signal, and the correction circuit sets a gain amount of the color difference signal corresponding to the noise pixel to be low. Device.
[0014]
A preferred aspect of the present invention is an image signal processing device further comprising an aperture generation circuit that generates an aperture signal of an input image signal, wherein the correction circuit sets a low level of the aperture signal corresponding to the noise pixel. is there.
[0015]
Another image signal processing apparatus according to the present invention further includes a register for storing a plurality of offset values, and the determination circuit selectively takes an arbitrary offset value from the plurality of offset values stored in the register, The fetched offset value is added to or subtracted from at least one of the first and second reference ranges to change and control the first and second reference ranges.
[0016]
According to the present invention, the first reference range and the second reference range set for each target pixel are changed and controlled according to the imaging conditions and the like. For example, when the imaging condition for obtaining the original image signal is low illuminance and there is a lot of random noise, the S / N ratio of the image decreases. In such a case, if you want to reduce the noise of the image even if the resolution is sacrificed to some extent, the second reference range is narrowed, and not only the original pixel defect but also random noise with a large noise component is interpolated. Try to remove it. As described above, according to the present invention, flexible noise correction can be performed according to imaging conditions and the like.
[0017]
The image signal processing apparatus according to a preferred aspect of the present invention further includes an automatic gain control circuit that adjusts a gain so that a signal level of an input image signal falls within a predetermined range, and the determination circuit includes the automatic gain control circuit. An arbitrary offset value is selected from a plurality of offset values stored in the register according to the gain amount. The image signal processing apparatus according to another preferred aspect of the present invention further includes an exposure control circuit that controls an exposure amount of a solid-state imaging device that photoelectrically converts incident light and accumulates information charges, and the determination circuit includes the exposure An arbitrary offset value is selected from a plurality of offset values stored in the register in accordance with the exposure amount selected by the control circuit.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a block diagram showing a schematic configuration of an image signal processing apparatus according to an embodiment of the present invention. This image signal processing apparatus receives a CCD output signal (original image signal) composed of sequentially read pixel values from a CCD image sensor, and uses luminance signal generation processing and color signal generation processing as original signal processing. On the other hand, noise correction processing is also performed by detecting noise pixels.
[0020]
The input CCD output signal is input to the memory circuit 3. The memory circuit 3 has a plurality of line memories and a plurality of latches, and stores image signals for an appropriate number of lines. Here, for example, it is configured to store image signals for three lines, and as shown in FIG. 2, the image signal P ₀ of the target pixel and the image signals P _{1 to} P of a plurality of peripheral pixels adjacent to the target pixel. Stores ₈ . Then, the image signal stored in the memory circuit 3 is output to the determination circuit 2 and the delay circuit 4. The determination circuit 2 sets the first reference range J and the second reference range K based on the input image signal, and detects pixel defects and random noise (noise pixels) included in the CCD output signal.
[0021]
FIG. 3 is a diagram illustrating a method for setting the first and second reference ranges J and K with reference to a plurality of peripheral pixels P _{1 to} P ₈ adjacent to the target pixel P ₀ . The vertical direction in FIG. 3 corresponds to the signal level. First, the maximum level Lmax and the minimum level Lmin of the peripheral pixels P _{1 to} P ₈ are generated, and the maximum level Lmax and the minimum level Lmin are set as the first determination reference value A and the second determination reference value B, respectively. A range from the first determination reference value A to the second determination reference value B is defined as a first reference range J. Subsequently, the peripheral pixels P _{1 to} P ₈ are averaged to generate an average level Lav, and a third determination reference value is obtained by adding or subtracting the difference ΔL between the maximum level Lmax and the minimum level Lmin to the average level Lav. C, a fourth determination reference value D is generated. A range from the third determination reference value C to the fourth determination reference value D is defined as a second reference range K.
[0022]
The determination circuit 2 compares the signal level of the image signal of the target pixel P ₀ with the first to fourth determination reference values A to D, and is included in any of the first and second reference ranges J and K. To determine whether the target pixel P ₀ is a pixel defect or a noise pixel. When the signal level of the target pixel P ₀ is equal to or higher than the third determination reference value C or equal to or lower than the fourth determination reference value D and is not included in any of the first and second reference ranges J and K, the target The pixel is determined to be a pixel defect that does not include an image signal in the signal. On the other hand, when the signal level of the target pixel P ₀ is equal to or higher than the first determination reference value A and lower than the third determination reference value C, or equal to or lower than the second determination reference value B and higher than the fourth determination reference value D. That is, when it is not included in the first reference range J and is included in the second reference range K, the target pixel P ₀ is determined to be a noise pixel including a noise component exceeding a predetermined level in the signal. The When the signal level of the target pixel P ₀ is smaller than the first determination reference value A and larger than the second determination reference value B, that is, when it is included in the first reference range J, the target pixel P ₀ is a noise. It is determined that the pixel signal is a normal pixel signal.
[0023]
Then, the determination circuit 2 generates determination signals Da and Db corresponding to the respective determination results. For example, when the target pixel P ₀ is detected as a pixel defect, the determination signal Da is raised to the “H (High)” level. On the other hand, when the target pixel P ₀ is detected as a noise pixel, the determination signal Db is raised to “H” level.
[0024]
Note that the setting method of the first reference range J and the second reference range K may be changed as follows. For example, a predetermined offset value OF is stored in the register 6 and, as shown in FIG. 4, the offset value OF is added to or subtracted from the first and second determination reference values A and B. And fourth determination reference values C and D are generated. When setting the offset value OF, a suitable offset value for determining a pixel defect and a noise pixel by performing a simulation or the like is preferably used to determine the pixel defect and the noise pixel included in the CCD output signal. Can be detected.
[0025]
The determination signal Da is used for controlling the interpolation processing circuit 8. The interpolation processing circuit 8 performs interpolation processing on the CCD output signal that has passed through the delay circuit 4. The interpolation processing circuit 8 acquires pixel values of peripheral pixels used for interpolation of the target pixel from the CCD output signal input from the delay circuit 4. For example, the delay amount of the delay circuit 4 is the timing at which the determination signal Da corresponding to a certain pixel (target pixel) is output from the determination circuit 2, and all the pixel values of peripheral pixels necessary for interpolation of the target pixel are interpolated. It is set to be stored in the circuit 8. When the determination signal Da corresponding to the target pixel is at “H” level, the interpolation processing circuit 8 performs an interpolation process using the pixel values of the held peripheral pixels, and obtains the pixel value of the target pixel as The obtained interpolation value is output. On the other hand, when the determination signal Da corresponding to the target pixel is at the “L” level, the interpolation processing is not performed, and the pixel value input from the delay circuit 4 is output to the target pixel as it is. In this way, the interpolation processing circuit 8 generates and outputs an image signal obtained by performing the interpolation processing on the pixel defect.
[0026]
The luminance signal generation circuit 10 generates a luminance signal Y based on the image signal output from the interpolation processing circuit 8. The color signal generation circuit 12 generates color difference signals U and V based on the image signal output from the interpolation processing circuit 8. The luminance gain adjustment circuit 14 and the color gain adjustment circuit 16 adjust the gain of the luminance signal Y generated by the luminance signal generation circuit 10 and the color difference signal generated by the color signal generation circuit 12, respectively, and the luminance signal after gain adjustment. Y ′ and the color difference signals U ′ and V ′ after gain adjustment are output to a signal processing circuit or the like at the subsequent stage.
[0027]
Here, the gain amount used in the color gain adjustment circuit 16 is variably controlled by the color gain control circuit 18. When the determination signal Db output from the determination circuit 2 is “L” level, the color gain control circuit 18 sets the color gain for the color difference signal of the corresponding pixel to a standard value, while the determination signal Db is “H”. In the case of “level”, the color gain is set to a value smaller than the standard value. In this way, the color of the noise pixel is lightened. As a result, the noise pixel has a color different from the actual color. By displaying the color lightly, the flickering of the image due to the noise is suppressed, and the noise becomes inconspicuous.
[0028]
FIG. 5 is a processing flowchart for explaining the operation of the apparatus described above. The determination circuit 2 sequentially captures the CCD output signal (S50), whether the pixel value is not less than the third determination reference value C or not more than the fourth determination reference value D (S55), and the pixel value is the first. It is determined whether or not the determination criterion value A is greater than or equal to the third criterion value C and less than the third criterion value C, or less than the second criterion value B and less than the fourth criterion value D (S60). Accordingly, determination signals Da and Db are generated. Specifically, when the determination circuit 2 determines that the pixel value is greater than or equal to the third determination reference value C or less than or equal to the fourth determination reference value D (S55), the determination signal Da is set to the “H” level. Thus, the interpolation processing circuit 8 is instructed to perform interpolation processing (S65). Further, when the pixel value is less than the third determination reference value C and greater than the fourth determination reference value D (S55) and is equal to or greater than the first determination reference value A or equal to or less than the second determination reference value B. (S60), the determination circuit 2 raises the determination signal Db to the “H” level, and accordingly, the color gain control circuit 18 changes the color gain set in the color gain adjustment circuit 16 to a value smaller than the standard value. (S70). On the other hand, when the pixel value is less than the first determination reference value A and greater than the second determination reference value B, the determination circuit 2 lowers both the determination signals Da and Db to the “L” level, thereby interpolating. The processing circuit 8 does not execute the interpolation process, and the color gain is kept at the standard value in the color gain control circuit 18. Based on the image signal output from the interpolation processing circuit 8, the luminance signal generation circuit 10 and the color signal generation circuit 12 generate the luminance signal Y and the color difference signals U and V, respectively (S75), and the luminance gain adjustment circuit 14, The color gain adjustment circuit 16 performs gain adjustment for multiplying these Y, U, and V signals by the set gain amount (S80). At this time, if the color gain is changed to a value smaller than the standard value for the color difference signals U and V in step S70, the gain adjustment is performed using the changed color gain. Is called. The gain-adjusted Y ′, U ′, V ′ signals are output to the outside of the apparatus (S85).
[0029]
As a result, noise correction is performed on the pixel defect by interpolation processing, and noise correction on the image is made inconspicuous on the image by reducing the color gain.
[0030]
The first to fourth determination reference values A to D can be changed according to, for example, the imaging conditions of the CCD image sensor. For example, a plurality of predetermined offset values OF are stored in the register 6 and the offset values OF selectively read according to the conditions are added to or subtracted from the first to fourth determination reference values A to D. It is realized by doing. For example, for the CCD output signal obtained under bright imaging conditions, the above first to fourth determination reference values A to D that are subjected to interpolation processing for pixel defects and color gain reduction processing for noise pixels are used. adopt. However, for a CCD output signal obtained under low-illumination imaging conditions where the frequency of noise pixels is high, for example, as shown in FIG. 6, the offset value OF1 is subtracted from the third determination reference value C. A new third criterion value C ′ is set, and an offset value OF2 is added to the fourth criterion value D to obtain a new fourth criterion value D ′. Thus, the third determination reference value C is set lower than normal, and the fourth determination reference value D is set higher than normal. As a result, noise pixels having relatively high levels are regarded as pixel defects, and interpolation processing is performed. According to this setting, at low illuminance, a part of random noise is corrected so that it cannot be distinguished from surrounding pixels by interpolation. In other words, at high illuminance, only pixel defects are interpolated to maintain high resolution, while at low illuminance, image noise is reduced even if the resolution is sacrificed to some extent. Noise correction can be performed.
[0031]
Illuminance information for performing this threshold change can be acquired based on gain control information in an AGC (Auto Gain Control) circuit 21, for example, as shown in FIG. The AGC 21 circuit determines the gain amount according to the gain amount setting signal AG set by the gain setting circuit 22, and gives the determined gain amount to the CCD output signal so that the signal level of the CCD output signal is within a predetermined range. Adjust the level so that it falls within the range. That is, since control is performed such that the luminance gain is increased at low illuminance, the determination circuit 2 selectively reads the offset value OF from the register 6 in conjunction with this control, and the first to fourth determination reference values A to It can be configured to automatically change D. Further, as shown in FIG. 8, the first to fourth determination reference values A to D can be changed and controlled using an exposure control circuit that controls the exposure time for the CCD image sensor in accordance with the illuminance of the imaging state. . The exposure control circuit 31 compares the integration value of the CCD output signal with a predetermined appropriate range, and performs expansion / contraction control of the exposure time of the CCD image sensor based on the comparison result. In this case, the exposure amount determination signal ES instructing expansion / contraction of the exposure time is also output to the determination circuit 2, and the determination circuit 2 selectively reads the offset value OF according to the exposure amount determination signal ES. Can do. Thus, the first to fourth determination reference values A to D can be changed in conjunction with the exposure time, that is, the illuminance condition.
[0032]
Further, the above-described apparatus employs color gain adjustment as noise correction processing for the noise pixel Pb, which is noise when the threshold value B is greater than or equal to the threshold value B and less than the threshold value A. However, other noise correction processing that makes noise inconspicuous without interpolation processing may be employed. For example, a configuration in which the intensity of the aperture signal is switched in units of pixels according to the determination signal Db is possible. In this configuration, by reducing the intensity of the aperture signal with respect to the noise pixel Pb, the edge enhancement with respect to the noise pixel Pb is suppressed and can be made inconspicuous.
[0033]
【The invention's effect】
According to the image signal processing apparatus of the present invention, random noise is corrected in units of pixels. That is, since only the noise pixel can be selectively corrected, it is possible to appropriately correct the noise while avoiding the influence of the noise correction of the entire image.
[0034]
Also, instead of uniform noise correction, noise correction with different effects is adopted according to the noise intensity, and furthermore, noise intensity to which noise correction with different effects is applied can be variably controlled, By these, more suitable noise correction is realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an image signal processing apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a target pixel P ₀ and peripheral pixels.
FIG. 3 is an explanatory diagram illustrating a method for setting first and second reference ranges J and K with reference to a plurality of peripheral pixels P _{1 to} P ₈ adjacent to a target pixel P ₀ .
FIG. 4 is a schematic diagram illustrating the setting of first and second reference ranges.
FIG. 5 is a processing flowchart for explaining the operation of the apparatus.
FIG. 6 is a schematic diagram for explaining change control of the first and second reference ranges.
FIG. 7 is a block diagram showing a schematic configuration of an image signal processing apparatus according to an embodiment of the present invention provided with an AGC circuit.
FIG. 8 is a block diagram showing a schematic configuration of an image signal processing apparatus according to an embodiment of the present invention provided with an exposure control circuit.
[Explanation of symbols]
2 determination circuit, 3 memory, 4 delay circuit, 6 register, 8 interpolation processing circuit, 10 luminance signal generation circuit, 12 color signal generation circuit, 14 luminance gain adjustment circuit, 16 color gain adjustment circuit, 18 color gain control circuit, 21 AGC circuit, 22 gain setting circuit, 31 exposure control circuit.

Claims (8)

The image signal for displaying the reproduced image in one screen unit, among the plurality of pixels constituting the screen, the interpolation processing is performed with respect to time is a specific pixel Gae containing defects, including a noise component exceeding a predetermined level An image signal processing device that performs correction processing when the pixel is a noise pixel,
A first reference range is set based on the maximum level and the minimum level of the image signals of a plurality of peripheral pixels adjacent to the target pixel, and includes the first reference range and is wider than the first reference range. A second reference range is set, and when the signal level of the target pixel is outside the first reference range and within the second reference range, the target pixel is determined as the noise pixel, and the target pixel A determination circuit that determines the target pixel as the pixel defect when the signal level of the target pixel is outside the second reference range;
A correction circuit that performs level correction processing on the noise pixel based on the determination result of the determination circuit;
An interpolation circuit that performs an interpolation process based on signal levels of the plurality of peripheral pixels for the pixel defect based on a determination result of the determination circuit;
An image signal processing apparatus comprising: The image signal processing apparatus according to claim 1,
The determination circuit sets a range from the maximum level to the minimum level of the image signals of the plurality of peripheral pixels as the first reference range, and sets the maximum level and the average level of the image signals of the plurality of peripheral pixels as the average level. An image signal processing apparatus characterized in that a range from a level obtained by adding a difference from a minimum level to a level obtained by subtracting a difference between the maximum level and the minimum level from the average level is set as the second reference range. The image signal processing apparatus according to claim 1,
A register for storing a predetermined offset value;
The determination circuit sets a range from a maximum level to a minimum level of the image signals of the plurality of peripheral pixels as the first reference range, and adds the predetermined offset value to the maximum level to the maximum level. An image signal processing apparatus characterized in that a range up to a level obtained by subtracting the predetermined offset value is used as the second reference range. In the image signal processing device according to any one of claims 1 to 3,
A color signal generation circuit for generating a color difference signal from the input image signal;
The correction circuit sets a gain amount of a color difference signal corresponding to the noise pixel to be low;
An image signal processing apparatus. In the image signal processing device according to any one of claims 1 to 3,
An aperture generation circuit for generating an aperture signal of the input image signal;
The correction circuit sets a low level of an aperture signal corresponding to the noise pixel;
An image signal processing apparatus. In the image signal processing device according to any one of claims 1 to 5,
A register for storing a plurality of offset values;
The determination circuit selectively fetches an arbitrary offset value from a plurality of offset values stored in the register, and adds or subtracts the fetched offset value to at least one of the first and second reference ranges. Changing and controlling the first and second reference ranges;
An image signal processing apparatus. The image signal processing apparatus according to claim 6.
An automatic gain control circuit for adjusting the gain so that the signal level of the input image signal falls within a predetermined range;
The determination circuit selectively fetches an arbitrary offset value from a plurality of offset values stored in the register according to the gain amount of the automatic gain control circuit, and takes the fetched offset value as the first and second offset values. Adding or subtracting to at least one of the reference ranges to change and control the first and second reference ranges;
An image signal processing apparatus. The image signal processing apparatus according to claim 6.
An exposure control circuit for controlling the exposure amount of the solid-state imaging device that photoelectrically converts incident light and accumulates information charges;
The determination circuit selectively fetches an arbitrary offset value from a plurality of offset values stored in the register in accordance with an exposure amount selected by the exposure control circuit, and the fetched offset value is the first and first offset values. Adding or subtracting to at least one of the two reference ranges to change and control the first and second reference ranges;
An image signal processing apparatus.

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