JP2010178226A - Imaging apparatus, chromatic aberration suppressing method, and chromatic aberration suppressing circuit, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent coloring in the periphery of an overexposed image and to prevent its display. <P>SOLUTION: An imaging apparatus 10 extracts signals of primary colors at a plurality of positions around a predetermined pixel position from an image signal obtained by an imaging device in which color filters of primary colors of R, G and B are alternately arranged on a plurality of pixels that are two-dimensionally arranged in a predetermined array, and interpolates the signals at the predetermined pixel position. At that time, a neighboring overexposure detecting part 11 determines that a pixel under consideration is included in the periphery of overexposure when the level of peripheral pixels arranged in a neighborhood being within a predetermined range to the pixel under consideration included in an image composed of RGB signals exceeds a predetermined threshold. A clip level generating part 12 generates a clip level for suppressing the level of the pixel under consideration in accordance with the change amount of the levels of the pixel under consideration and the peripheral pixels. A suppression processing part 13 suppresses the level of the pixel under consideration and suppresses chromatic aberration that occurs in the pixel under consideration on the basis of the change amount of the levels and the clip level. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, a chromatic aberration suppression method, a chromatic aberration suppression circuit, and a program that are suitable for use when, for example, color information is interpolated in an image signal obtained through a Bayer color filter.

  In recent years, an imaging device such as an electronic camera has been required to have a small size, a high magnification, a large number of pixels, and a high image quality. However, it has become very difficult to manufacture a lens having high MTF (Modulation Transfer Function) characteristics corresponding to downsizing, high magnification, and multiple pixels. For this reason, by reducing the size of the lens, “chromatic aberration” occurs in which the in-focus position is shifted depending on the position and wavelength of the screen. Chromatic aberration includes not only “magnification chromatic aberration” in which the magnification of an image differs depending on colors but also “axial chromatic aberration” caused by a difference in focus position due to color, and a technique for suppressing chromatic aberration by signal processing has been proposed.

  Patent Document 1 describes a technique for suppressing color fringes around a high luminance.

JP 2007-133582 A

  By the way, when a bright part such as a metallic luster is imaged, since the part has high luminance, “whiteout” that becomes white due to chromatic aberration occurs. Conventional imaging devices have a narrow dynamic range and cannot accurately acquire high-luminance color information. However, with the recent increase in sensitivity of imaging devices, the dynamic range that can be acquired has expanded. However, along with this, it has become possible to accurately acquire even the color fringe color, such as chromatic aberration at high brightness, which has not appeared (cannot be acquired) until now, and the color fringe has influenced the image quality. .

FIG. 11 shows an example of a color fringe generated around a whiteout by suppressing chromatic aberration.
When the signal level of the Y signal (or any one of the RGB signals) is saturated, the overexposure 101 occurs. For example, the overexposure 101 is likely to occur in a high contrast image such as metallic luster or a light source, and thus the overexposure 101 is suppressed in chromatic aberration. However, a color fringe 102 may occur around the whiteout 101 due to the difference in the focal position on the optical axis. This is because there has been no effective method for suppressing axial chromatic aberration.

  Moreover, since the technique described in Patent Document 1 detects a whiteout peripheral pixel and performs achromatic processing when the pixel is purple, other colors (red and green) other than purple are used. The color fringe could not be hidden. For this reason, a technique for preventing the color fringe 102 from being displayed has been demanded.

  The present invention has been made in view of such a situation, and an object of the present invention is to suppress axial chromatic aberration so that a high-brightness image is not displayed with a color when a high-brightness image is displayed. To do.

The present invention provides a plurality of positions around a predetermined pixel position from an image signal obtained by an image sensor in which R, G, and B primary color filters are alternately arranged in a predetermined arrangement on a plurality of two-dimensionally arranged pixels. This is applied when the primary color signal is extracted and the signal at a predetermined pixel position is interpolated.
In this case, if the level of the peripheral pixels included in the image composed of the RGB signals and disposed within a predetermined range with respect to the target pixel exceeds a predetermined threshold, the target pixel is included in the periphery of the overexposure. To detect.
Next, a clip level for suppressing the level of the target pixel is generated in accordance with the amount of change in the level of the target pixel and surrounding pixels.
Then, based on the level change amount and the clip level, the level of the target pixel is suppressed, and chromatic aberration generated in the target pixel is suppressed.

  By doing so, it is possible to suppress chromatic aberration that occurs in the pixels in the surrounding areas.

  According to the present invention, since it is possible to suppress chromatic aberration that occurs in pixels around a whiteout, even if whiteout occurs in a part of an image, color fringes that occur around the whiteout can be suppressed. There is an effect that can be done.

1 is a block diagram illustrating an internal configuration example of an imaging device according to a first embodiment of the present invention. It is a block diagram which shows the internal structural example of the color fringe suppression part in the 1st Embodiment of this invention. It is a block diagram which shows the internal structural example of the smoothing process part in the 1st Embodiment of this invention. It is explanatory drawing which shows the example of the pixel of a Bayer arrangement | sequence in the 1st Embodiment of this invention. It is explanatory drawing which shows the example of the overexposure vicinity determination condition calculated | required from the absolute value of the G level of the surrounding pixel in the 1st Embodiment of this invention. It is explanatory drawing which shows the example of the clip level in the 1st Embodiment of this invention. It is a block diagram which shows the internal structural example of the imaging device in the 2nd Embodiment of this invention. It is explanatory drawing which shows the example of the pixel in the 2nd Embodiment of this invention. It is explanatory drawing which shows the example of the over-out vicinity determination condition calculated | required from the absolute value of the Y level of the surrounding pixel in the 2nd Embodiment of this invention. It is explanatory drawing which shows the example of the clip level in the 2nd Embodiment of this invention. Shows examples of color fringes that occur around white spots by suppressing axial chromatic aberration

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described. The description will be given in the following order.
1. First Embodiment (Color Fringe Suppression Processing: Example Using R, G, and B Signals)
2. Second Embodiment (Color Fringe Suppression Processing: Example Using Y Signal)
3. Modified example

<1. First Embodiment>
[Example of internal configuration of imaging device]

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the image signal processing device of the present invention is applied to the imaging device 10.

FIG. 1 shows an internal configuration example of the imaging apparatus 10.
The imaging device 10 includes a lens unit 1, a color filter 2, and an imaging element 3.

  The lens unit 1 is configured by an optical lens system or a diaphragm mechanism, and forms an image of a subject on the imaging surface of the imaging device 3. The image sensor 3 is composed of a plurality of photoelectric conversion elements arranged two-dimensionally. As this photoelectric conversion element, for example, a charge coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, or the like is used. Each photoelectric conversion element constitutes a plurality of pixels, and the position occupied by each photoelectric conversion element on the imaging surface corresponds to the pixel position.

  A red (R), green (G), or blue (B) color filter 2 is arranged on the two-dimensionally arranged pixels of the image sensor 3, and one per pixel is passed through the color filter 2. A color signal value is obtained. The color filter 2 uses a Bayer array that will be described later, and the filter width is, for example, 5 pixels × 5 pixels in the vertical direction and the horizontal direction, respectively. In the following description, when attention is paid to a certain pixel, the pixel is referred to as a “target pixel”, and a range of 5 pixels × 5 pixels around the target pixel is referred to as a “neighbor”. The incident light passes through the color filter 2 so that only each color component of the color filter 2 reaches the light receiving unit of the image sensor 3. That is, in the light receiving unit, the red (R), green (G), and blue (B) components are incident on different positions and photoelectrically converted.

  The imaging apparatus 10 also converts the signal output from the image sensor 3 into a digital signal, and performs a predetermined correction process on the digital signal converted by the analog / digital converter 4. A correction processing unit 5 is provided. The analog / digital converter 4 digitizes the electrical signals (analog signals) of the red (R), green (G), and blue (B) components supplied from the image sensor 3 and corrects the digital signals. Supply to part 5. The correction processing unit 5 performs processing such as shading correction for correcting luminance unevenness caused by the characteristics of the optical system and the imaging system, and pixel defect correction caused by a defect of the imaging device 3 and the like.

A color separation unit 7 for obtaining an RGB full color image is provided. The imaging apparatus 10 also includes an image processing unit 8 that performs processing such as gamma correction and contour enhancement on the signal. A configuration example of the color fringe suppressing unit 6 and specific contents of the processing will be described later.

  The image processing unit 8 performs signal processing (image processing) on the supplied image data (R, G, B signals) so as to process an image corresponding to the image data, and converts the image data into luminance. The signal Y and the color signals Cr and Cb are output.

FIG. 2 shows an internal configuration example of the color fringe suppressing unit 6.
The color fringe suppression unit 6 is used as a chromatic aberration suppression circuit for suppressing chromatic aberration. As a premise of the color fringe suppression processing of the present example, from an image signal obtained by the image sensor 3 in which R, G, and B primary color filters are alternately arranged in a predetermined arrangement on a plurality of pixels arranged two-dimensionally, Signals of primary colors at a plurality of positions around a predetermined pixel position are extracted. The extracted primary color signal around the predetermined pixel position is applied when the signal at the predetermined pixel position is interpolated.

  The color fringe suppression unit 6 generates a near whiteout detection unit 11 that detects the periphery of the overexposure from an image in which overexposure occurs, and a clip level that suppresses the color (color fringe) attached to the periphery of the overexposure. A clip level generation unit 12 is provided. Further, the color fringe suppression unit 6 includes a suppression processing unit 13 that suppresses the color attached to the periphery of the overexposure according to the clip level generated by the clip level generation unit 12, and a smoothing processing unit 14 that smoothes the image. .

  The adjacent white spot detection unit 11 refers to the luminance value of each pixel from the input R, G, and B signals, and determines whether or not it is greater than a predetermined threshold value (whether or not the signal level is saturated). ). At this time, the neighboring white-out detection unit 11 detects that the target pixel is out-of-white when the level of a peripheral pixel arranged within a predetermined range with respect to the target pixel included in the image composed of RGB signals exceeds a predetermined threshold. Detects being included in the vicinity. Then, the neighboring white spot detection unit 11 supplies the determination result (threshold judgment result) to the white spot suppression processing unit 13. This threshold value may be any value, but is used to detect a pixel in a portion where overexposure occurs. For this reason, generally, a sufficiently large value that is in the vicinity of the maximum value of the range of luminance values is set.

  The clip level generation unit 12 is a clip for suppressing the G color difference level of the pixel of interest (hereinafter referred to as “G level”) to a predetermined value in accordance with the amount of change in the luminance level of the pixel of interest and surrounding pixels. Generate a level.

  Along with the input image signal, the suppression processing unit 13 is supplied with information on the position of overexposure from the adjacent overexposure detection unit 11, and is supplied with the clip level from the clip level generation unit 12. Based on these pieces of information, the suppression processing unit 13 performs a process of suppressing color fringes that occur around the overexposure. Specifically, the suppression processing unit 13 suppresses the G color difference level based on the level change amount and the clip level, and suppresses chromatic aberration generated in the target pixel. For example, when a pixel with high luminance and a pixel with low luminance are arranged, the contrast ratio increases. In this case, since color fringe is likely to occur, the color fringe can be suppressed by suppressing the G color difference to a certain level according to the amount of change in the periphery.

  The smoothing processing unit 14 smoothes the color components of the target pixel and the peripheral pixels whose levels are suppressed by the suppression processing unit 13 using the color components included in the pixels around the peripheral pixels. For the smoothing processing unit 14, for example, a low pass filter (LPF) having a filter coefficient of (1, 2, 1) is used. Thereby, the discontinuity of the color component over a plurality of pixels caused by suppressing the color fringe is smoothed.

FIG. 3 shows an internal configuration example of the smoothing processing unit 14.
The smoothing processing unit 14 includes an SRAM (Static Random Access Memory) 21, a multiplier 22, an SRAM 23, an adder 24 and a divider 25.

  Each of the SRAMs 21 and 23 is a line memory that holds an image signal for one line. These are connected in series. When an image signal for one new line is supplied to the SRAM 21, the image signals held in the SRAM 23 are transferred in order. The output of the SRAM 21 is doubled by the multiplier 22 and supplied to the adder 24. The input of the SRAM 21 and the output of the SRAM 23 are supplied to the adder 24 as they are. The adder 24 adds all the input image signals and supplies the addition result to the divider 25. The divider 25 outputs a quarter of the addition result.

  That is, the smoothing processing unit 14 is a low-pass filter (1, 2, 1) in the vertical direction, and is connected in two stages in the vertical direction using a line memory (SRAM) that holds an image signal for one line. It is configured as follows. In FIG. 3, the lower SRAM holds data in the past (upper screen), and the upper SRAM holds newer (lower screen) data. At this time, the output phase of the image data is held in the SRAM 21 and is delayed by two lines with respect to the current signal output by being doubled by the multiplier 22.

  Next, a method for suppressing color fringe near high brightness before color separation will be described with reference to FIGS.

First, a place that satisfies all of the following conditions is detected as a place where chromatic aberration is likely to occur.
(1) There is a G signal having a certain level or more in the vicinity of the target pixel.
(2) The G signal of the peripheral pixel located in the vicinity of the target pixel has a change amount of a certain level or more.
Then, processing for suppressing color fringes is performed by restricting the color component (G color difference) in accordance with the amount of change in G color difference of neighboring pixels located in the vicinity of the target pixel.

In the following description, a Bayer array image will be described for the sake of simplicity.
FIG. 4 shows an example of pixels in a Bayer array.

  In a single-plate imaging device, a color filter is used to separate subject light obtained through a lens into three primary colors of R (red), G (green), and B (blue). A color filter using a Bayer array is often used. In the Bayer array, G signal pixels to which a luminance signal contributes are arranged in a checkered pattern, and R signal and B signal pixels are arranged in a checkered pattern in the remaining part.

In each pixel, only one color data of R, G and B signals can be obtained. For this reason, data of other colors is obtained by color separation processing that performs an interpolation operation using the outputs of surrounding pixels. If the position is R44, the missing G signal and B signal are generated by interpolation. In this example, the pixel located at R44 is referred to as a “target pixel”. Further, in order to distinguish from “G _grad ” described later, the notation of the G signal is described as “Gr” for convenience.

Next, processing for detecting overexposure and suppressing color fringes will be described.
As a precondition, the pixel value of the same color as R44 (R22, R24, R26, R42, R44, R46, R62, R64, R66) located in the vicinity of the target pixel R44 is used, and Gr44 in the pixel at the same position as R44 is used. Ask for. Gr44 can be derived by an existing color separation method. Regarding the color separation method, for example, adaptive interpolation is described in US Pat. No. 5,629,734, and local color component correlation is described in US Pat. No. 4,642,678, which method is used. May be.

  First, the adjacent overexposure detection unit 11 determines whether or not the G signal whose G level exceeds the high luminance condition within a certain range with respect to the target pixel R44 is greater than or equal to a certain value. The presence or absence of occurrence is determined. Here, in order to simplify the description, only the pixels in the vertical direction will be described.

FIG. 5 shows an example of a whiteout neighborhood determination condition obtained from the absolute value of the G level of surrounding pixels.
The target pixel is Gr44, and the Gr levels of Gr34 and Gr54 which are peripheral pixels of Gr44 are shown in FIG. The gradient of the G level in the vicinity of the target pixel Gr44 is obtained from the G level of the peripheral pixels. This slope is G _grad .

  The neighboring white spot detection unit 11 determines whether there is a pixel in which the level of the G signal exceeds a predetermined threshold among the peripheral pixels, for example, among the G signals in the vertical direction (Gr14, Gr34, Gr54, Gr74). Ask for. Then, when there is such a pixel, the neighboring white spot detection unit 11 determines that the target pixel R44 is a pixel located in the vicinity of the pixel where the white spot has occurred.

Next, a color fringe correction method will be described.
When performing color separation, the color separation unit 7 interpolates color components using the G color difference (RG, BG) and G color ratio (R / G, B / G) for the R signal and the B signal. It is carried out. In the color fringe suppression algorithm around the high brightness according to the present invention, the color component of the G color difference or G color ratio is limited (clipped) to the region near the whiteout, thereby adding an extra color around the whiteout. Suppress the coloring so that there is no.

  As described above, there is a large change in G level as a condition that color fringes are likely to occur in the periphery of a high-luminance image. The color component of the target pixel increases as the G level of the G signal in the surrounding area changes greatly. Is greatly limited. For example, an absolute value (| Gr34−Gr54 |) of a difference between Gr34 and Gr54 is selected as the amount of change in the G level of the peripheral pixels in the vertical direction among the peripheral pixels arranged in the vicinity of the target pixel. At this time, a value obtained by averaging the absolute values of the differences in the G level in the vertical direction of the G signal in the surrounding area may be selected. Further, the largest value may be selected from the absolute values of the difference between the G levels of the peripheral pixels.

FIG. 6 shows an example of processing for generating a clip level.
The clip level generation unit 12 generates a clip level that suppresses the G color difference based on the gradient G _grad obtained in FIG. The clip level is generated by the following equation (1), and the level of the target pixel is suppressed as the amount of change in the level of the target pixel and the surrounding pixels is larger. Here, each variable is defined as follows.
TH _grad : level of change amount of G signal not clipped C _min : minimum clip level C _max : level without clip (C _min and C _max represent RG or BG)
K: The slope of the clip level according to the amount of change in the G level

  As shown in FIG. 6, generally, the smaller the G level change amount of the peripheral pixels, the smaller the clip level is selected. For example, the G color difference (R−G, B−G) and the G color ratio (R / G, B / G) are greatly suppressed as the amount of change in the G level of the surrounding pixels increases in the vicinity of the whiteout. For this reason, the level of the G color difference is limited by the clip as the brightness changes rapidly.

In accordance with the above-described conditions, the suppression processing unit 13 obtains G44 having the same phase as the target pixel R44 by interpolation, and derives a G color difference. Then, the suppression processing unit 13 uses the clip level (C _clp ) corresponding to R44 obtained this time to clip a value where the derived G color difference exceeds the clip level (C _clp ). As a result, the overexposed portion is output as it is, but the color component is restricted in the portion where the color is added around the overexposed portion, and the color fringe is suppressed.

  However, as the color component is clipped, the color components of the target pixel and the peripheral pixels appear discontinuously. For this reason, the smoothing processing unit 14 smoothes the color components using the color components of the peripheral pixels. Here, since it is possible to derive the G signal of the surrounding pixels based on the precondition, each G color difference (C24, C64) is obtained by interpolating the G signal having the same phase with respect to R24 and R64 in the vertical direction. )

The smoothing processing unit 14 applies the LPF of the filter coefficient (1, ₂ , 1) to the obtained G color difference (C24, C _clp , C64) to smooth the color component, and the color component is discontinuous. To prevent from appearing. Then, the smoothing processing unit 14 obtains a correction value Cv in the vertical direction.

By the way, when the G color difference is increased by the above algorithm due to the occurrence of intense aberration in the surroundings, the suppression processing unit 13 performs adjustment such as not correcting the G level. The G color difference of the target pixel R44 is derived. Further, a pixel R44 ′ obtained by correcting the target pixel R44 is obtained by adding the corrected G color difference (C _clp ) to the obtained G color difference. Thereby, axial chromatic aberration can be suppressed and color fringe can be suppressed.

  According to the imaging device 10 according to the first embodiment described above, even if a whiteout occurs in a part of an image due to imaging of a high-luminance part, color fringes generated around the whiteout are suppressed. can do. For this reason, the display device has an effect of preventing the color fringe from being displayed around the whiteout. In addition, since the setting of the clip level and the change of the clip coefficient can be arbitrarily performed, there is an effect that the color fringe suitable for various shooting environments can be easily suppressed. In addition, since the color fringe suppression processing of this example can be applied regardless of the signal processing at the subsequent stage, there is an effect that the application range is widened.

<2. Second Embodiment>
[Example of internal configuration of imaging device]

Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
The process of suppressing the color fringe around the overexposure can be performed regardless of the color separation. In this example, unlike the above-described first embodiment, an example in which color fringe suppression processing is performed on the R, G, and B planes after color separation will be described. In the following description, parts corresponding to those in FIG. 1 already described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The color fringe suppression process can be applied after color separation by detecting overexposure using the luminance Y. In this case, not the G color difference but the color difference Cr or the color difference Cb may be selected as the correction target. The algorithm for color fringe suppression processing described above detects places where color fringes around high brightness are likely to appear, and limits color components such as saturation Cr, Cb, and G color differences in such places. Control fringe.

FIG. 7 illustrates an internal configuration example of the imaging device 30.
The imaging device 30 includes the same processing blocks as the imaging device 10 according to the first embodiment described above. However, after the correction processing unit 5, the color separation unit 7 separates the signals into R, G, and B signals, and the color fringe suppression unit 31 performs luminance Y and color difference Cr or luminance Y obtained from the R, G, and B signals. Color fringe suppression processing is performed based on the color difference Cb. Since the color fringe suppression processing of this example is performed after color separation, it is determined by a predetermined threshold that the peripheral pixels are not high in saturation value and high in luminance value.

Here, the process of deriving the luminance signal (Y signal) and the color difference signals (Cr signal, Cb signal) will be described.
First, the color fringe suppression unit 31 generates a luminance signal (Y signal) by calculating the following equation (2) using the RGB signals supplied from the color separation unit 7.

  Y = 0.3R + 0.6G + 0.1B (2)

  In Expression (2), Y represents a luminance value (Y signal value), R represents a signal level of the R signal (red component amount), and G represents a signal level of the G signal (green component amount). B indicates the signal level of the B signal (the amount of the blue component). Then, the obtained luminance signal (Y signal) is supplied to a line memory (not shown).

  The line memory is composed of a volatile semiconductor memory such as SRAM or DRAM (Dynamic Random Access Memory), and temporarily holds image data in units of pixel columns (lines) in the horizontal direction of the screen. The line memory holds the supplied image data (Y signal) for a predetermined number of lines for a predetermined period, and holds the Y signal at a timing corresponding to the output timing of the color difference signals (Cr signal, Cb signal). Is output.

  The color fringe suppression unit 31 calculates the color signals (Cr signal and Cb signal) by calculating the following equations (3) and (4) using the RGB signals supplied from the color separation unit 7. Generate.

Cr (R−Y) = 0.7R−0.6G−0.1B (3)
Cb (B−Y) = − 0.3R−0.6G + 0.9B (4)

  In Expressions (3) and (4), Cr (R−Y) and Cb (B−Y) on the left side indicate the values of the respective color signals, and R, G, and B on the right side are the above expressions (2). It is the same as the case of.

Based on the calculated Y signal, Cr signal, and Cb signal, the color fringe suppression unit 31 corrects chromatic aberration such as longitudinal chromatic aberration and lateral chromatic aberration included in the image data, and the corrected Cr signal and Cb Output a signal. In this example, (| Cr | + | Cb |) may be used as the saturation, or (Cr ² + Cb ² ) ^1/2 may be used.

FIG. 8 shows an example of a luminance signal (Y signal) for each pixel.
In this example, in order to facilitate later explanation, an example in which a luminance signal (Y signal) is assigned to each pixel is shown. Then, using the luminance signal (Y signal), a clip level is generated as in the first embodiment described above.

FIG. 9 shows an example of the inclination obtained from the absolute value of the luminance Y of the peripheral pixels located in the vicinity of the target pixel Y44.
When the pixel of interest is Y44, the luminance level of the Y signals Y24 and Y64 around Y44 (hereinafter also referred to as “Y level”) is obtained by converting the RGB signal. The slope of the Y level in the vicinity of the target pixel Y44 is obtained from the Y levels of the surrounding pixels. This slope is Y _grad .

FIG. 10 shows an example of processing for generating a clip level.
The clip level generation unit 12 generates a clip level for suppressing the Y level based on the slope Y _grad obtained in FIG. The clip level is generated by the following equation (5). Here, each variable is defined as follows.
TH _grad : level of change in luminance Y that does not clip C _min : minimum clip level C _max : level without clipping K: slope of clip level according to the amount of change in luminance Y

  In general, a smaller clip level is selected as the amount of change in luminance Y of surrounding pixels is larger. That is, the level of the brightness Y is limited by the clip as the brightness changes rapidly. In this way, in the vicinity of overexposure, the greater the amount of change in the luminance Y of the surrounding pixels, the greater the saturation is suppressed. Note that the processing by the neighboring white spot detection unit 11 and the smoothing processing unit 14 is processing using G color difference in the first embodiment described above, using saturation, and thus detailed description thereof. Is omitted.

  According to the imaging apparatus 30 according to the second embodiment described above, even an image that includes a high-intensity image and causes overexposure is processed without causing color fringe around the overexposure. be able to. For this reason, it is possible to easily correct the color fringe around the high luminance. In addition, since the suppression of coloring can be performed in a scalable manner, the present invention can be applied regardless of the subsequent signal processing.

<3. Modification>
In the imaging devices according to the first and second embodiments described above, the case where the Bayer array is used for the color filter 2 has been described. However, other arrays may be used.
Further, the filter coefficient of the LPF used in the smoothing processing unit 14 is not limited to (1, 2, 1), and an arbitrary coefficient may be used. Alternatively, a non-linear LPF may be used so that saturation is not increased.

  Further, the same processing may be performed for a plurality of directions such as the vertical direction, the horizontal direction, and the oblique direction of the target pixel to obtain a plurality of correction values Cv, Ch, and Cd. Of these correction values, the one having the smallest absolute value is selected to obtain a G color difference corrected for the target pixel, or a value obtained by averaging the correction values Cv, Ch, and Cd is a G color difference corrected by the target pixel. You may choose as

  Further, a recording medium that records a program code of software that realizes the functions of the first and second embodiments described above may be supplied to the system or apparatus. It goes without saying that the function is also realized by a computer (or a control device such as a CPU) of the system or apparatus reading and executing the program code stored in the recording medium.

  As a recording medium for supplying the program code in this case, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like is used. Can do.

  Further, the functions of the above-described embodiment are realized by executing the program code read by the computer. In addition, based on the instruction of the program code, an OS (Operating System) running on the computer performs part or all of the actual processing. The case where the functions of the above-described embodiment are realized by the processing is also included.

  Further, the present invention is not limited to the above-described embodiment, and it is needless to say that various other configurations can be taken without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Lens part, 2 ... Color filter, 3 ... Image pick-up element, 4 ... Analog-digital conversion part, 5 ... Correction processing part, 6 ... Color fringe suppression part, 7 ... Color separation part, 8 ... Image processing part, 10 ... Image pickup device, 11 ... Neighborhood white-out detection unit, 12 ... Clip level generation unit, 13 ... Suppression processing unit, 14 ... Smoothing processing unit, 21 ... SRAM, 22 ... Multiplier, 23 ... SRAM, 24 ... Adder, 25 ... Divisor, 30 ... Imaging device, 31 ... Color fringe suppression unit

Claims (9)

A primary color signal at a plurality of positions around a predetermined pixel position from an image signal obtained by an image sensor in which color filters of primary colors of R, G, and B are alternately arranged in a predetermined arrangement on a plurality of pixels arranged two-dimensionally When the signal at the predetermined pixel position is interpolated and the level of peripheral pixels included in the image made up of RGB signals and arranged within a predetermined range with respect to the target pixel exceeds a predetermined threshold, A neighboring overexposure detecting unit for detecting that the target pixel is included in the periphery of overexposure;
A clip level generation unit that generates a clip level for suppressing the level of the target pixel according to the amount of change in the level of the target pixel and the surrounding pixels;
An image pickup apparatus comprising: a suppression processing unit that suppresses a level of the target pixel based on the level change amount and the clip level, and suppresses chromatic aberration generated in the target pixel. The adjacent overexposure detection unit is a pixel that is located in the vicinity of the pixel in which the overexposure occurs when there is a pixel that is at a level exceeding the predetermined threshold among at least one of the peripheral pixels. Determine that there is
The imaging apparatus according to claim 1, wherein the clip level generation unit generates the clip level that suppresses the level of the target pixel as the amount of change in the level of the target pixel and the surrounding pixels increases. The imaging according to claim 2, further comprising: a smoothing processing unit that smoothes the color components of the target pixel and the peripheral pixels suppressed by the suppression processing unit using color components included in pixels around the peripheral pixels. apparatus. The imaging apparatus according to claim 3, wherein the levels of the target pixel and the peripheral pixels are G color difference levels or luminance levels obtained by converting the RGB signals. The level change amount is a level difference value of the peripheral pixels arranged in a predetermined direction of the target pixel, a value obtained by averaging the difference values of the peripheral pixels, or a value of the largest level among the peripheral pixels. The imaging device according to claim 1 or 2. The imaging device according to claim 3, wherein the smoothing processing unit is a low-pass filter. A primary color signal at a plurality of positions around a predetermined pixel position from an image signal obtained by an image sensor in which color filters of primary colors of R, G, and B are alternately arranged in a predetermined arrangement on a plurality of pixels arranged two-dimensionally When the signal at the predetermined pixel position is interpolated and the level of the peripheral pixels included in the image made up of RGB signals and arranged in the vicinity within the predetermined range with respect to the target pixel exceeds the predetermined threshold value A step of determining that the target pixel is included in the vicinity of overexposure;
Generating a clip level for suppressing the level of the target pixel according to the amount of change in the level of the target pixel and the peripheral pixel;
Suppressing the level of the target pixel based on the amount of change in the level and the clip level, and suppressing chromatic aberration generated in the target pixel. A primary color signal at a plurality of positions around a predetermined pixel position from an image signal obtained by an image sensor in which color filters of primary colors of R, G, and B are alternately arranged in a predetermined arrangement on a plurality of pixels arranged two-dimensionally When the signal at the predetermined pixel position is interpolated and the level of the peripheral pixels included in the image made up of RGB signals and arranged in the vicinity within the predetermined range with respect to the target pixel exceeds the predetermined threshold value A neighboring overexposure detecting unit for detecting that the pixel of interest is included in the periphery of the overexposure;
A clip level generation unit that generates a clip level for suppressing the level of the target pixel according to the amount of change in the level of the target pixel and the surrounding pixels;
A chromatic aberration suppression circuit, comprising: a suppression processing unit configured to suppress a level of the target pixel based on the level change amount and the clip level and suppress chromatic aberration generated in the target pixel. A primary color signal at a plurality of positions around a predetermined pixel position from an image signal obtained by an image sensor in which color filters of primary colors of R, G, and B are alternately arranged in a predetermined arrangement on a plurality of pixels arranged two-dimensionally When the signal at the predetermined pixel position is interpolated and the level of the peripheral pixels included in the image made up of RGB signals and arranged in the vicinity within the predetermined range with respect to the target pixel exceeds the predetermined threshold value A step of determining that the target pixel is included in the vicinity of overexposure;
Generating a clip level for suppressing the level of the target pixel according to the amount of change in the level of the target pixel and the peripheral pixel;
A program for causing a computer to execute the method, including: suppressing a level of the target pixel based on the change amount of the level and the clip level, and suppressing a chromatic aberration generated in the target pixel.