JP2010141454A - Image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus capable of quickly and exactly controlling the gain of image data captured repeatedly. <P>SOLUTION: Raw image data output from a pre-processing circuit 20 is written in a raw image area 32a at an SDRAM 32 by a data write-in circuit 30w. The image data stored in the raw image area 32a is read by a data read-out circuit 30r. A post-processing circuit 34 applies processing to the image data read by the data read-out circuit 30r. Wherein, the processing contains gain control which refers to a gain factor. A CPU 26 refers to an intensity distribution of raw image data interested by the data write-in circuit 30w, and specifies a percentage of pixels belonging to a default low intensity range in the raw image data interested by the data write-in circuit 30w. Moreover, the CPU 26 adjusts the capacity of a gain factor corresponding to the pixels belonging to the default low intensity range among gain factors referred for gain control, with reference to the percentage specified in the above way. As the result, the gain of the image data can be quickly and exactly controlled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus which is applied to a video camera and adjusts the gain of image data forming a moving image.

An example of this type of device is disclosed in Patent Document 1. According to this background art, the ratio of pixels belonging to a predetermined low luminance area is calculated with reference to a histogram representing the luminance distribution of image data. The gradation curve is changed with reference to the calculated ratio, and the image data is subjected to luminance correction (gain control) according to the changed gradation curve.
JP 2001-189862 A

  However, the background art assumes gain control in a printer, that is, gain control of image data corresponding to a still image, and there is a limit to gain control of image data that is repeatedly captured like a moving image.

  Therefore, a main object of the present invention is to provide an image processing apparatus that can quickly and accurately control the gain of image data that is repeatedly captured.

  An image processing apparatus according to the present invention (10: reference numeral corresponding to the embodiment; the same applies hereinafter) includes a writing means (30w) for writing image data into the memory (32), and a reading for reading out the image data written by the writing means from the memory. Means (30r), processing means (34) for performing processing including gain control with reference to a gain coefficient on the image data read by the reading means, and pixels belonging to a predetermined luminance range are converted into image data to be noticed by the writing means Corresponding to the pixels belonging to the predetermined luminance range among the gain factors referred to for gain control, specifying means (S9 to S15) for specifying the occupying ratio with reference to the luminance distribution of the image data noted by the writing means Adjusting means (S31 to S53) for adjusting the magnitude of the specific gain coefficient with reference to the ratio specified by the specifying means.

  The image data is written into the memory by the writing means. The image data written by the writing unit is read from the memory by the reading unit. The processing means performs processing including gain control with reference to a gain coefficient on the image data read by the reading means. The specifying unit specifies a ratio of pixels belonging to the predetermined luminance range in the image data focused on by the writing unit with reference to a luminance distribution of the image data focused on by the writing unit. The adjusting means adjusts the magnitude of the specific gain coefficient corresponding to the pixel belonging to the predetermined luminance range among the gain coefficients referred to for gain control with reference to the ratio specified by the specifying means.

  As described above, the ratio of the pixels belonging to the predetermined luminance range is specified with reference to the luminance distribution of the image data noticed by the writing unit. On the other hand, gain control is performed on the image data read by the reading unit. Furthermore, the magnitude of the specific gain coefficient is adjusted with reference to the ratio specified from the image data noted by the writing means. As a result, the gain of the image data can be controlled quickly and accurately.

  Preferably, the image data noted by the writing means corresponds to image data according to the first format, and the processing executed by the processing means is a conversion process for converting the format of the image data read by the reading means into the second format. including.

  More preferably, the first format corresponds to a format in which each of a plurality of pixels has any one color information of a plurality of colors, and the second format has a format in which each of a plurality of pixels has all color information of a plurality of colors. It corresponds to.

  Preferably, the gain control corresponds to a processing operation for increasing the gain as the gain coefficient increases, and the adjustment means includes coefficient correction means (S33, S41, S49) for increasing the specific gain coefficient as the ratio increases.

  More preferably, the predetermined luminance range includes a plurality of low luminance ranges different from each other, the specifying unit performs a ratio specifying process corresponding to each of the plurality of low luminance ranges, and the coefficient correcting unit includes a plurality of low luminance ranges. Coefficient correction processing is executed corresponding to each.

  Preferably, the image forming apparatus further includes a creation unit (S7) that creates a histogram representing a luminance distribution of image data focused by the writing unit in parallel with the writing process of the writing unit, and the specifying unit refers to the histogram created by the creating unit. To do.

  Preferably, the image processing apparatus further includes an image pickup unit (16, 20) having an image pickup surface for capturing the object scene and repeatedly outputting image data noticed by the writing unit.

  The image processing program according to the present invention includes a writing means (30w) for writing image data to the memory (32), a reading means (30r) for reading image data written by the writing means from the memory, and an image read by the reading means. Image data in which pixels belonging to a predetermined luminance range are noted by the writing means to the processor (26) of the image processing apparatus (10) including processing means (34) for performing processing including gain control with reference to the gain coefficient for the data Specific step (S9 to S15) for specifying the ratio of the image data with reference to the luminance distribution of the image data to be noticed by the writing means, and the pixels belonging to the predetermined luminance range among the gain coefficients referred to for gain control Execute adjustment steps (S31 to S53) to adjust the magnitude of the corresponding specific gain coefficient with reference to the ratio specified in the specific step This is an image processing program.

  The image processing method according to the present invention comprises a writing means (30w) for writing image data to the memory (32), a reading means (30r) for reading image data written by the writing means from the memory, and an image read by the reading means. An image processing method executed by an image processing apparatus (10) including processing means (34) for performing processing including gain control with reference to a gain coefficient on data, wherein pixels belonging to a predetermined luminance range are noted by a writing means Specific step (S9 to S15) for specifying the ratio of the image data in the image data with reference to the luminance distribution of the image data noted by the writing means, and a predetermined luminance range among the gain coefficients referred to for gain control An adjustment step for adjusting the magnitude of the specific gain coefficient corresponding to the pixel belonging to the pixel with reference to the ratio specified by the specific step Comprising a-flops (S31 ~ S53).

  According to the present invention, the ratio of the pixels belonging to the predetermined luminance range is specified with reference to the luminance distribution of the image data noticed by the writing unit. On the other hand, gain control is performed on the image data read by the reading unit. Furthermore, the magnitude of the specific gain coefficient is adjusted with reference to the ratio specified from the image data noted by the writing means. As a result, the gain applied to the image data can be controlled quickly and accurately.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  Referring to FIG. 1, a digital video camera 10 of this embodiment includes a focus lens 12 and an aperture unit 14 driven by drivers 18a and 18b, respectively. The optical image of the object scene that has passed through these members is irradiated onto the imaging surface of the imager 16 and subjected to photoelectric conversion by a plurality of light receiving elements provided on the imaging surface. The imaging surface is covered with a primary color Bayer array color filter 16f shown in FIG. 2, and the charge generated by each of the plurality of light receiving elements is any one of R (Red), G (Green), and B (Blue). Have information.

  When the power is turned on, the CPU 26 instructs the driver 18c to repeat the exposure operation and the charge readout operation in order to start through image processing under the imaging task. The driver 18c exposes the imaging surface in response to a vertical synchronization signal Vsync periodically generated from an SG (Signal Generator) (not shown), and raster scans the charges generated on the imaging surface in response to the same vertical synchronization signal Vsync. Read in mode. From the imager 16, a raw image signal based on the read charges is periodically output.

  The preprocessing circuit 20 performs processing such as CDS (Correlated Double Sampling), AGC (Automatic Gain Control), and A / D conversion on the raw image signal of each frame output from the imager 16, and raw image data that is a digital signal. Are output periodically. The output raw image data is periodically written in the raw image area 32 a of the SDRAM 32 by the data writing circuit 30 w provided in the memory control circuit 30.

  Thereafter, the raw image data stored in the raw image area 32a is periodically read out with a delay of one frame by a data reading circuit 30r provided in the memory control circuit 30. The post-processing circuit 34 performs processing such as white balance adjustment, color separation, γ correction, noise removal, YUV conversion, and gain control on the raw image data read by the data reading circuit 30r, and the YUV format generated thereby. Are periodically output to the memory control circuit 30. The output image data is periodically written in the YUV image area 32b of the SDRAM 32 by the data writing circuit 30w.

  The LCD driver 36 periodically reads the image data stored in the YUV image area 32b through the data read circuit 30r, and drives the LCD monitor 38 based on the read image data. As a result, a real-time moving image (through image) of the object scene is displayed on the monitor screen.

  Referring to FIG. 3, an evaluation area EVA is allocated at the center of the imaging surface. In addition to the above-described processing, the preprocessing circuit 20 executes simple Y conversion processing that simply converts raw image data into Y data.

  The AE evaluation circuit 22 integrates Y data belonging to the evaluation area EVA among the Y data generated by the preprocessing circuit 20 every time the vertical synchronization signal Vsync is generated. The calculated integral value is output to the CPU 26 as an AE evaluation value.

  Further, the AF evaluation circuit 24 extracts the high frequency component of the Y data belonging to the same evaluation area EVA from the Y data output from the preprocessing circuit 20, and the vertical synchronization signal Vsync is generated from the extracted high frequency component. Integrate every time. The calculated integral value is output to the CPU 26 as an AF evaluation value.

  The CPU 26 executes through image AE processing based on the output from the AE evaluation circuit 22 in parallel with the through image processing, and calculates an appropriate EV value. The aperture amount and the exposure time that define the calculated appropriate EV value are set in the drivers 18b and 18c, respectively. As a result, the brightness of the through image is appropriately adjusted.

  The CPU 26 also executes through-image AF processing based on the output from the AF evaluation circuit 24 under a continuous AF task in parallel with the through-image processing. The focus lens 12 is set to the focal point by the driver 18a when the output of the AF evaluation circuit 24 satisfies the AF activation condition. As a result, the focus of the through image is appropriately adjusted.

  When a recording start operation is performed by the key input device 28, the CPU 26 activates the I / F 40. The I / F 40 periodically reads the image data stored in the YUV image area 32b through the data reading circuit 30r, and writes the read image data to the moving image file in the recording medium 42 in a compressed state. The I / F 40 is stopped by the CPU 26 when a recording end operation is performed on the key input device 28. As a result, the image data recording process is completed.

  The post-processing circuit 34 is configured as shown in FIG. The white balance adjustment circuit 46 adjusts the white balance of the raw image data given from the data reading circuit 30r. The raw image data having the adjusted white balance is subjected to color separation processing by the color separation circuit 48. As a result, interpolated image data in which each pixel has all the R, G, and B color information is created.

  The noise removal circuit 50 removes noise from the interpolated image data output from the color separation circuit 48, and the γ correction circuit 52 performs γ correction on the interpolated image data output from the noise removal circuit 50. Interpolated image data having γ characteristics is converted into YUV format image data by the YUV conversion circuit 54. Of the converted image data, U data and V data are output as they are, and Y data is output through gain control by the amplifier 56, that is, through contrast adjustment.

  The CPU 26 determines the luminance distribution of the object scene image under the luminance distribution determination task in parallel with the through image processing. Specifically, the CPU 26 takes in the Y data simply generated by the preprocessing circuit 20 and creates a histogram representing the luminance distribution based on the taken Y data. The CPU 26 further calculates a ratio of pixels having luminance levels belonging to each of the predetermined low luminance ranges R1 to R3 to all pixels corresponding to one frame with reference to the created histogram.

  Referring to FIG. 5, low luminance range R1 corresponds to a range having a luminance level of 0% to 5%, low luminance range R2 corresponds to a range having a luminance level of 5% to 10%, and low luminance. The range R3 corresponds to a range having a luminance level of 10% to 20%. The Y data is expressed by 8 bits, and the luminance level of “255” corresponds to 100%.

  In the following, the proportion of pixels having a luminance level belonging to the low luminance range R1 is defined as “RT1”, the proportion of pixels having a luminance level belonging to the low luminance range R2 is defined as “RT2”, and the low luminance range R3 The ratio of pixels having a luminance level belonging to is defined as “RT3”.

  The calculated ratios RT1 to RT3 are registered in a register designated under the luminance distribution determination task in the registers RGST1 or RGST2 shown in FIG. The designated register is changed between the registers RGST1 and RGST2 every time the vertical synchronization signal Vsync is generated.

  The CPU 26 adjusts the gain coefficient referred to by the amplifier 56 under a contrast adjustment task in parallel with the through image processing. Specifically, the CPU 26 takes in the interpolated image data given from the γ correction circuit 52 and sequentially designates each of the plurality of pixels forming the taken in interpolated image data. The CPU 26 also designates a register different from the register designated under the luminance distribution determination task under the contrast adjustment task. Further, the CPU 26 adjusts the gain coefficient corresponding to the designated pixel in the following manner based on the luminance level of the designated pixel and the ratios RT1 to RT3 registered in the designated register.

  When the luminance level of the designated pixel belongs to the low luminance range R1, the CPU 26 determines whether or not the ratio RT1 registered in the specified register exceeds the threshold value TH. If the determination result is affirmative, the gain coefficient of the specified pixel is determined. Is set to “G1 + α”, and if the determination result is negative, the gain coefficient of the designated pixel is set to “G1−α”.

  When the luminance level of the designated pixel belongs to the low luminance range R2, the CPU 26 determines whether or not the ratio RT2 registered in the specified register exceeds the threshold value TH. If the determination result is affirmative, the gain coefficient of the specified pixel is determined. Is set to “G2 + α”, and if the determination result is negative, the gain coefficient of the designated pixel is set to “G2−α”.

  When the luminance level of the designated pixel belongs to the low luminance range R3, the CPU 26 determines whether or not the ratio RT3 registered in the specified register exceeds the threshold value TH. If the determination result is affirmative, the gain coefficient of the specified pixel is determined. Is set to “G3 + α”, and if the determination result is negative, the gain coefficient of the designated pixel is set to “G3-α”.

  When the detected luminance level is out of any of the low luminance ranges R1 to R3, the CPU 26 sets the gain coefficient to “1.0”. The constant G1 indicates “1.2”, the constant G2 indicates “1.5”, and the constant G3 indicates “2.0”. The constant α indicates “0.1”.

  Therefore, as shown in FIG. 7, the gain coefficient is set to “G1−α” when RT1 ≦ TH, and is set to “G1 + α” when RT1> TH. The gain coefficient is set to “G2−α” when RT2 ≦ TH, and is set to “G2 + α” when RT2> TH. Further, the gain coefficient is set to “G3−α” when RT3 ≦ TH, and is set to “G3 + α” when RT3> TH.

  The luminance distribution determination task calculates the ratios RT1 to RT3 by paying attention to the raw image data before being written in the SDRAM 30. In contrast, the contrast adjustment task adjusts the gain coefficient for gain control of YUV image data based on the raw image data read from the SDRAM 30. Further, the reading of the raw image data from the SDRAM 30 is executed with a delay of one frame with respect to the writing of the raw image data to the SDRAM 30. Therefore, as shown in FIG. 8, the ratios RT1 to RT3 calculated by the brightness determination task are used for gain control of YUV image data corresponding to the raw image data referenced for the calculation process.

  The amplifier 56 shown in FIG. 4 increases the gain of Y data as the gain coefficient set in this way increases. As a result, when the Y data input to the amplifier 56 has the histogram shown in FIG. 9A, the low-luminance level pixels decrease and the medium-luminance level pixels increase as shown in FIG. 9B. Y data is output from the amplifier 56.

  The CPU 26 executes a plurality of tasks including a luminance distribution determination task shown in FIG. 10 and a contrast adjustment task shown in FIGS. 11 to 13 in parallel. Note that control programs corresponding to these tasks are stored in the flash memory 44.

  Referring to FIG. 10, in step S1, one of registers RGST1 and RGST2 is designated. When the vertical synchronization signal Vsync is generated, YES is determined in step S3, Y data output from the preprocessing circuit 20 is captured in step S5, and a histogram showing the luminance distribution of the pixels forming the captured Y data is displayed in step S7. Create with.

  In step S9, the ratio of the pixels belonging to the low luminance range R1 to the Y data captured in step S5 is calculated as “RT1”. In step S11, the ratio of the pixels belonging to the low luminance range R2 to the Y data captured in step S5 is calculated as “RT2”. In step S13, the ratio of the pixels belonging to the low luminance range R3 to the Y data captured in step S5 is calculated as “RT3”. In any of steps S9 to S11, the histogram created in step S5 is referred to.

  In step S15, the ratios RT1 to RT3 calculated in this way are registered in the designated register. When the registration process is completed, the process proceeds to step S17, and the designation register is changed between the registers RSGT1 and RGST2. When the change of the designated register is completed, the process returns to step S3.

  Referring to FIG. 11, in step S21, it is determined whether or not the vertical synchronization signal Vsync is generated. In step S23, a register different from the register specified by the luminance distribution determination task is specified. Therefore, if the register RGST1 is specified by the luminance distribution determination task, the register RGST2 is specified by the contrast adjustment task. If the register RGST2 is specified by the luminance distribution determination task, the register RGST1 is specified by the contrast adjustment task.

  In step S25, the interpolated image data output from the γ correction circuit 52 shown in FIG. 4 is fetched. In step S27, the leading pixel of the fetched interpolated image data is designated, and in step S29, the luminance level of the designated pixel is detected. In step S31, it is determined whether or not the detected luminance level belongs to the low luminance range R1, in step S39 it is determined whether or not the detected luminance level belongs to the low luminance range R2, and in step S47, it is detected. It is determined whether or not the brightness level belongs to the low brightness range R3.

  If “YES” in the step S31, the process proceeds to a step S33 to determine whether or not the ratio RT1 registered in the register designated in the step S23 exceeds the threshold value TH. If YES, the gain coefficient corresponding to the designated pixel is set to “G1 + α” in step S35. If NO, the gain coefficient corresponding to the designated pixel is set to “G1-α” in step S37. When the process of step S35 or S37 is completed, the process proceeds to step S57.

  If “YES” in the step S39, the process proceeds to a step S41 to determine whether or not the ratio RT2 registered in the register designated in the step S23 exceeds the threshold value TH. If YES, the gain coefficient corresponding to the designated pixel is set to “G2 + α” in step S43. If NO, the gain coefficient corresponding to the designated pixel is set to “G1-α” in step S45. When the process of step S43 or S45 is completed, the process proceeds to step S57.

  If “YES” in the step S47, the process proceeds to a step S49, and it is determined whether or not the ratio RT2 registered in the register designated in the step S23 exceeds a threshold value TH. If YES, the gain coefficient corresponding to the designated pixel is set to “G3 + α” in step S51. If NO, the gain coefficient corresponding to the designated pixel is set to “G1-α” in step S53. When the process of step S51 or S53 is completed, the process proceeds to step S57.

  If all of steps S31, S39, and S47 are NO, the process proceeds to step S55, and the gain coefficient corresponding to the designated pixel is set to “1.0”. When the process of step S55 is completed, the process proceeds to step S57.

  In step S57, it is determined whether or not the designated pixel is the final pixel of the interpolated image data captured in step S25. If NO, the next pixel is designated in step S59, and then the process returns to step S29. If YES, the process directly returns to step S21.

  As can be seen from the above description, the raw image data output from the preprocessing circuit 20 is written into the raw image area 32a of the SDRAM 32 by the data writing circuit 30w. The image data stored in the raw image area 32a is read by the data reading circuit 30r. The post-processing circuit 34 performs processing including gain control with reference to the gain coefficient on the image data read by the data reading circuit 30r.

  The CPU 26 refers to the ratio of the pixels belonging to the low luminance ranges R1 to R3 to the raw image data noted by the data writing circuit 30w, that is, the ratios RT1 to RT3, referring to the luminance distribution of the raw image data noted by the data writing circuit 30w. (S9 to S15). The CPU 26 also refers to the ratios RT1 to RT3 specified in the above manner for the magnitudes of the specific gain coefficients corresponding to the pixels belonging to the low luminance ranges R1 to R3 among the gain coefficients referred to for gain control. Adjust (S31 to S53).

  As described above, the ratio of the pixels belonging to the low luminance ranges R1 to R3 is specified with reference to the luminance distribution of the raw image data focused by the data writing circuit 30w. On the other hand, gain control is performed on the raw image data read by the data reading circuit 30r. Further, the magnitude of the specific gain coefficient is adjusted with reference to the ratios RT1 to RT3 specified from the raw image data noted by the data writing circuit 30w. As a result, the gain of the image data can be controlled quickly and accurately.

  In this embodiment, a digital video camera is assumed, but the present invention can also be applied to an image processing apparatus such as a video recorder.

It is a block diagram which shows the structure of one Example of this invention. It is an illustration figure which shows an example of a structure of the color filter applied to the FIG. 1 Example. It is an illustration figure which shows an example of the allocation state of the evaluation area in an imaging surface. It is a block diagram which shows an example of a structure of the post-processing circuit applied to FIG. 1 Example. It is an illustration figure which shows an example of the allocation state of low-luminance range R1-R3. FIG. 3 is an illustrative view showing one example of a configuration of a register applied to the embodiment in FIG. 1; 5 is a graph showing an example of a gain coefficient referred to by the amplifier of the embodiment in FIG. FIG. 2 is a timing diagram showing a part of the operation of the embodiment in FIG. 1. (A) is a graph which shows an example of the luminance distribution before performing contrast adjustment, (B) is a graph which shows an example of the luminance distribution after performing contrast adjustment. It is a flowchart which shows a part of operation | movement of CPU applied to the FIG. 1 Example. It is a flowchart which shows a part of other operation | movement of CPU applied to the FIG. 1 Example. It is a flowchart which shows a part of other operation | movement of CPU applied to the FIG. 1 Example. FIG. 12 is a flowchart showing yet another portion of behavior of the CPU applied to the embodiment in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Digital video camera 16 ... Imager 22 ... AE evaluation circuit 24 ... AF evaluation circuit 26 ... CPU
32 ... SDRAM
44 ... Flash memory

Claims (9)

Writing means for writing image data to memory,
Reading means for reading out the image data written by the writing means from the memory;
Processing means for performing processing including gain control with reference to a gain coefficient on the image data read by the reading means;
A specifying unit for specifying a ratio of pixels belonging to a predetermined luminance range in the image data focused on by the writing unit with reference to a luminance distribution of the image data focused on by the writing unit; and reference for the gain control An image processing apparatus comprising: an adjusting unit that adjusts the magnitude of a specific gain coefficient corresponding to a pixel belonging to the predetermined luminance range among the gain coefficients to be adjusted with reference to a ratio specified by the specifying unit. The image data noted by the writing means corresponds to the image data according to the first format,
The image processing apparatus according to claim 1, wherein the process executed by the processing unit includes a conversion process for converting the format of the image data read by the reading unit into a second format. The first format corresponds to a format in which each of a plurality of pixels has color information of any one of a plurality of colors,
The image processing apparatus according to claim 2, wherein the second format corresponds to a format in which each of a plurality of pixels has all color information of the plurality of colors. The gain control corresponds to a processing operation for increasing the gain as the gain coefficient increases,
The image processing apparatus according to claim 1, wherein the adjustment unit includes a coefficient correction unit that increases the specific gain coefficient as the ratio increases. The predetermined luminance range includes a plurality of different low luminance ranges;
The specifying means executes a ratio specifying process corresponding to each of the plurality of low luminance ranges,
The image processing apparatus according to claim 4, wherein the coefficient correction unit executes coefficient correction processing corresponding to each of the plurality of low luminance ranges. A creation unit that creates a histogram representing a luminance distribution of image data to be noticed by the writing unit in parallel with the writing process of the writing unit;
The image processing apparatus according to claim 1, wherein the specifying unit refers to a histogram created by the creating unit.   The image processing apparatus according to claim 1, further comprising an imaging unit that has an imaging surface that captures an object scene and that repeatedly outputs image data of interest by the writing unit. Write means for writing image data into a memory, read means for reading image data written by the write means from the memory, and processing including gain control with reference to a gain coefficient for the image data read by the read means In a processor of an image processing apparatus provided with processing means,
A specifying step of specifying a ratio of pixels belonging to a predetermined luminance range in the image data noted by the writing means with reference to a luminance distribution of the image data noted by the writing means, and reference for the gain control An image processing program for executing an adjustment step of adjusting a magnitude of a specific gain coefficient corresponding to a pixel belonging to the predetermined luminance range among the gain coefficients to be adjusted with reference to a ratio specified by the specifying step. Write means for writing image data into a memory, read means for reading image data written by the write means from the memory, and processing including gain control with reference to a gain coefficient for the image data read by the read means An image processing method executed by an image processing apparatus including processing means,
A specifying step of specifying a ratio of pixels belonging to a predetermined luminance range in the image data noted by the writing means with reference to a luminance distribution of the image data noted by the writing means, and reference for the gain control An image processing method comprising: an adjustment step of adjusting a magnitude of a specific gain coefficient corresponding to a pixel belonging to the predetermined luminance range among the gain coefficients to be adjusted with reference to a ratio specified by the specifying step.

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