JP4295149B2 - Color shading correction method and solid-state imaging device - Google Patents

Description

  The present invention relates to a method for correcting color shading that occurs due to color mixture on a color filter in a solid-state imaging device, and a solid-state imaging device.

  Conventionally, when a solid-state imaging device uses, for example, a solid-state imaging device having a plurality of light-receiving elements on which microlenses are formed, the amount of light received by each light-receiving element varies greatly depending on the incident direction of light under the influence of the microlenses. To do. Generally, light is incident on the light receiving element at the peripheral edge of the solid-state image sensor, so that the amount of received light is reduced as compared with the light receiving element at the center. As a result, so-called shading occurs in which the luminance at the peripheral edge of the obtained image decreases.

The shading correction apparatus described in Patent Document 1 generates horizontal direction shading correction data and vertical direction shading correction data by cumulatively adding the vertical and horizontal center data based on a reference image captured by an image sensor. Are stored in the horizontal shading correction memory and the vertical shading correction memory, respectively, and the image data captured by the image sensor is multiplied by the corresponding horizontal shading correction data and vertical shading correction data by a multiplier. To correct shading.
JP-A-9-130603

  The shading correction apparatus described in Patent Document 1 described above has a gain correction type shading correction function for multiplying captured image data by shading correction data, and in most of the generally disclosed shading correction apparatuses. The reciprocal of the shading characteristic of each color obtained by individual adjustment or the like by such gain correction type shading correction is calculated by a multiplier for each photographed image data. However, in such a gain correction, in order to correct the product sum of the light source spectrum at the time of individual adjustment and the in-plane dependence of the element spectrum that is the cause of shading, shading correction is illegally performed when the light source spectrum changes. Sometimes.

  By the way, in the shading that occurs in the photographed image, the color shading that occurs due to the loss of uniformity in the sensitivity plane due to the color filter of each light receiving element is more visually harmful than the luminance shading that reduces the peripheral light amount by the lens. . This kind of color shading is likely to occur as the pixel pitch becomes finer and is caused by light color mixing in the color filter. Color shading in each pixel is transmitted through the color (RGB) filter in that pixel and incident. Depending on the wavelength dependence of the light to be emitted, it is greatly deviated from the long wavelength side.

  The present invention eliminates such disadvantages of the prior art and directly corrects light color mixing, which is considered to be the cause of color shading in a narrow-pitch image sensor, to correct for the shooting scene (color temperature of light source, spectrum). An object of the present invention is to provide a solid-state imaging device and a color shading correction method using an in-plane spectroscopic color shading correction of an image sensor and an individual adjustment method of constants used for the correction with improved robustness.

  According to the present invention, there are a plurality of light receiving portions arranged in the row and column directions so as to form an imaging surface and performing photoelectric conversion, and incident light is split into a plurality of color components in each of the plurality of light receiving portions. An image pickup means for providing an image signal by splitting the picked-up object scene image into a first color component, a second color component and a third color component by the filter; The signal processing means includes a signal processing means for processing, and the signal processing means uses the third color component indicated by the pixel adjacent to one side of the pixel position showing the first color component as the first correction component. Based on the first correction component and the first color shading correction data corresponding to the pixel position, the first color component is subjected to color shading correction according to the pixel position, and one side of the pixel position indicating the second color component The third color indicated by the pixels adjacent to Color shading for correcting the color shading of the second color component according to the pixel position based on the second correction component and the second color shading correction data corresponding to the pixel position A correction means is included.

  In addition, a plurality of light receiving portions that are arranged in the row and column directions so as to form an imaging surface and photoelectrically convert, and each of the plurality of light receiving portions includes a filter that splits incident light into a plurality of color components. An imaging process that forms an image signal by splitting the captured scene image into a first color component, a second color component, and a third color component by using this filter using an imaging device; and In the color shading correction method including the signal processing step of performing signal processing, the signal processing step uses the third color component indicated by the pixel adjacent to one side of the pixel position indicating the first color component as the first correction component. Based on the first correction component and the first color shading correction data corresponding to the pixel position, the first color component is subjected to color shading correction according to the pixel position, and the pixel position indicating the second color component Close to one side of The third color component indicated by the prime is used as the second correction component, and the second color component is determined according to the pixel position based on the second correction component and the second color shading correction data corresponding to the pixel position. And a color shading correction step of correcting the color shading.

  As described above, according to the solid-state imaging device of the present invention, the output of the red pixel and the blue pixel is subjected to color shading correction by subtracting the value obtained by multiplying the output of the green pixel adjacent to each side by a predetermined coefficient, When the predetermined coefficient is a coefficient that can be freely set at each pixel position, color shading due to light source color mixture can be optimally corrected regardless of the photographing light source. As described above, in the in-plane spectral correction type color shading correction of the element, the in-plane uniformity of the element spectrum can be enhanced by the linear matrix circuit capable of setting a predetermined coefficient non-uniformly in the screen.

  In addition, the present invention uses a predetermined coefficient in the linear matrix circuit as a function that monotonously increases with an increase in the pixel position of the image. The amount can be greatly reduced. In addition, this function can be made a limited shape to further reduce the memory usage.

  Next, embodiments of the solid-state imaging device according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the solid-state imaging device 10 of the embodiment captures incident light from the object scene in the optical system 12 and operates the operation unit 14 to control each unit by the system control unit 16 and the timing generator 18. The object image is captured by the imaging unit 20 under control, and an image signal obtained by performing signal processing on the captured image by the pre-processing unit 22 and the signal processing unit 22 is connected to the bus 26 for the compression recording processing unit 28. , Compressed by the display unit 30, displayed on the display unit 30, and recorded by the recording unit 32. Note that portions not directly related to understanding the present invention are not shown and redundant description is avoided.

  Although a specific configuration is not shown in the optical system 12, there are a lens, an aperture adjustment mechanism, a shutter mechanism, a zoom mechanism, an automatic focus (AF) adjustment mechanism, an automatic exposure (AE) adjustment mechanism, and the like. include. This lens is an optical lens disposed almost in front of a lens barrel (not shown), and a plurality of lenses may be used in combination. The aperture adjustment mechanism adjusts the amount of light incident on the imaging unit 20 by changing the diameter of the opening, and the shutter mechanism is a mechanical shutter that blocks the optical path by closing the opening. The zoom mechanism adjusts the position of the lens for zooming, and the automatic focus adjustment mechanism adjusts the focus according to the distance between the object scene and the imaging device 10.

  This optical system 12 is controlled by a control signal 106, and an aperture adjustment mechanism, a shutter mechanism, a zoom mechanism, and an automatic focus adjustment mechanism are driven to capture a desired object scene image and enter the imaging surface of the imaging unit 20. This is a light incident mechanism. Further, since the width that can be measured at a time is limited at the time of photometry, for example, the aperture or electronic shutter may be driven to obtain photometric data in several steps. In the following description, each signal is specified by the reference number of the connecting line in which it appears.

  The operation unit 14 is a manual operation device that inputs an operator's instruction, and supplies an operation signal 104 to the system control unit 16 in accordance with the operator's manual operation state, for example, a stroke operation of a shutter button (not shown). It has the function to do.

  The system control unit 16 is a control function unit that controls and controls the overall operation of the apparatus in response to an operation signal 104 supplied from the operation unit 12. For example, the system control unit 16 in this embodiment supplies control signals 106, 108, and 110 to the optical system 12, the timing generator 18, and the bus 26, respectively, in response to the operation signal 104. The system control unit 16 may include, for example, a central processing unit (CPU) 72 as shown in FIG.

  The timing generator 18 includes an oscillator that generates a basic clock (system clock) for operating the apparatus 10, and supplies the basic clock 112 to the system control unit 16 according to the control signal 108, for example. Although not shown in FIG. 1, the timing generator 18 supplies a basic clock to almost all the blocks and divides the basic clock to generate various timing signals.

  Further, the timing generator 18 of the present embodiment generates a timing signal based on the control signal 108 supplied from the system control unit 16. For example, a timing signal 114 indicating a vertical synchronization signal, a horizontal synchronization signal, an electronic shutter pulse, and the like is generated and supplied to the imaging unit 20. Further, a timing signal 118 such as a sampling pulse for correlated double sampling and a conversion clock for analog / digital conversion is generated and supplied to the preprocessing unit 24.

  Although the specific configuration is not illustrated, the imaging unit 20 includes an imaging surface 300 that forms one screen of a captured image and a horizontal transfer path. The imaging surface 300 includes a light receiving unit 302 corresponding to each of a plurality of pixels, a microlens 304 provided in each of the light receiving units 302, and a vertical transfer path 308, as shown in part in FIG. The imaging unit 20 has a function of photoelectrically converting an object scene image formed on the imaging surface 300 into an electric signal 118. In this embodiment, for example, a charge coupled device (CCD) or a metal Any image sensor such as an oxide film type semiconductor (Metal Oxide Semiconductor: MOS) may be used. The imaging unit 20 of this embodiment is controlled by the timing signal 114 to photoelectrically convert incident light 102 incident from the object scene in each photosensitive unit, and convert the signal charge obtained thereby into an analog electric signal 118. Output.

  In this embodiment, as shown in FIG. 3, the plurality of light receiving portions 302 on the imaging surface 300 are optical sensors that photoelectrically convert light into an electrical signal corresponding to the amount of received light when receiving incident light. A photodiode is used. The plurality of light receiving portions 302 are arranged in a matrix with red R, green G, and blue B color filters, and use, for example, a honeycomb arrangement in which every other position is shifted in the row direction and the column direction. However, they may be arranged in a square matrix at a constant pitch in the row direction and the column direction. Further, the arrangement pattern of these color filters is arranged in a completely checkered pattern in which the green pixels G are arranged in a square lattice shape, and further, the red pixels R or the blue pixels B are arranged diagonally across the green pixels G. G square lattice RB may be a perfect checkered pattern, green pixels G are arranged in a checkered pattern, and red pixels R and blue pixels B are surrounded by green pixels G, and each row and each column of the matrix is a green pixel G. And a Bayer pattern arranged to include any one of the red pixel R and the blue pixel B. Although a large number of pixels are actually arranged on the imaging surface 300, only a small number of pixel arrangements are shown in FIG. 3 to avoid complication. Each of the plurality of light receiving units 302 may include a high sensitivity and a low sensitivity light receiving element to realize a wide dynamic range.

  The preprocessing unit 22 is controlled by the timing signal 116 and has a function of performing analog signal processing on the analog electric signal 118 indicating an image. The pre-processing unit 22 includes a correlated double sampling circuit (Correlated Double Sampling: CDS), a gain control amplifier (GCA), an analog / digital (A / D) converter, and the like. These circuits may process the electrical signal 118 to generate and output an analog image signal 120.

  The signal processing unit 24 performs digital signal processing on the input digital image signal 120, supplies the generated digital image signal 122 to the bus 26, and supplies the digital image signal 130 to the bus 26 and compression recording processing. Supply to part 28. In the signal processing unit 24 of this embodiment, the digital image signal 120 is input from the preprocessing unit 22, and the digital signal processing is performed according to the control signal 122, which is the control signal 110 from the system control unit 16 via the bus 26. Do.

  In this embodiment, the signal processing unit 24 is configured as shown in FIG. 2 and performs digital signal processing in accordance with the control signal 122. The signal processing unit 24 temporarily stores the input digital image signal 120 in the image memory 40, performs offset correction by the offset correction unit 42, and then performs normal linear processing by a first linear matrix (LMTX) correction unit 46. A matrix operation is performed, and the second LMTX correction unit 50 performs color shading correction. The digital image signal after shading correction is converted into a white balance (WB) correction unit 54, a gamma (γ) correction unit 60, Processing is performed by the synchronization processing unit 64, the color difference matrix (CMTX) correction unit 68, and the like. These circuits may be connected to an EEPROM (Electrically Erasable Programmable Read-Only Memory).

  The offset correction unit 42 corrects a deviation from the reference voltage level for the digital image signal corresponding to each color component.

  The first LMTX correction unit 46 reads out the digital image signal in the image memory 40 and applies a 3 × 3 matrix (linear matrix) to the signal linear to the subject luminance, thereby causing the red pixel R, green Linear conversion is performed on the primary color signals from the pixel G and the blue pixel B to enhance color reproduction and perform color correction.

In the present embodiment, the first LMTX correction unit 46 calculates, for example, from the outputs of the red pixel R and the blue pixel B in the digital image signal by the following equations (1) and (2) that are simplified linear matrix operations. Results R ′ and B ′ may be calculated.
R ′ = R−α ₁ Gr (1)
B ′ = B−β ₁ Gb (2)
At this time, the constants α ₁ and β ₁ indicate predetermined matrix constants, the output Gr indicates the output of the closest green pixel Gr on one side of the red pixel R, for example, the lower right side, and the output Gb indicates the blue pixel The output of the green pixel Gb closest to one side of B, for example, the lower right side, is shown.

The EEPROM 48 connected to the first LTMX correction unit 46 stores predetermined matrix constants used for normal linear matrix calculation. In the present embodiment, the predetermined matrix constants α ₁ and β ₁ are stored. .

  The second LMTX correction unit 50 performs color shading correction on the digital image signal which is the calculation result of the first LMTX correction unit 46, and outputs the outputs of the red pixel R and the blue pixel B in the digital image signal. Color shading may be performed by subtracting or adding a value obtained by multiplying the output of the green pixel G adjacent to one side of the pixel by a predetermined coefficient. In the present embodiment, the second LMTX correction unit 50 may perform color shading correction by linear matrix calculation using the above equations (1) and (2). In particular, a predetermined matrix constant is converted into a digital image. The coefficient is a coefficient that can be freely set at each pixel position of the image indicated by the signal.

At this time, in the second LMTX correction unit 50, the pixel positions (x, y) of the red pixel R and the blue pixel B are set as the predetermined matrix constants α ₁ and β _{1 in} the equations (1) and (2). Coefficients α ₂ (x, y) and β ₂ (x, y) having coordinate dependency are used corresponding to. In this embodiment, a plurality of matrix coefficients α ₂ (x, y) and β ₂ (x, y) corresponding to various zoom magnifications and aperture values may be stored in the EEPROM 52.

  The second LMTX correction unit 50 subtracts the output of a different color pixel that is close to one side of this pixel from the output of the desired pixel, such as a honeycomb, Bayer or G square lattice RB complete checkered pattern. Conveniently corresponds to the output of the plurality of light receiving units 302 arranged. As described above, the second LMTX correction unit 50 can set a non-uniform coefficient in the screen and enhances the in-plane uniformity of the element spectrum by color shading correction using linear matrix calculation.

  In this embodiment, the WB correction unit 54 may be connected to the integrating circuit 58 to perform WB correction processing on the digital image signal after color shading correction.

  Further, the γ correction unit 60 performs γ correction on the digital image signal in accordance with the gradation characteristics of the imaging unit 20, and the synchronization processing unit 64 performs the synchronization process.

  The CMTX correction unit 68 performs linear conversion on the color difference signals (Cr, Cb) converted into luminance / color difference signals for the red pixel R, green pixel G, and blue pixel B of the digital image signal, and uses them for image display. The format is converted into luminance data Y and color difference data (R−Y) and (B−Y). These luminance data and color difference data are obtained by multiplying and calculating a mixing ratio determined for each color. In addition, the CMTX correction unit 68 of this embodiment may directly supply the digital image signal 130 subjected to the color difference matrix correction to the compression recording processing unit 28.

  The signal processing unit 24 is connected to the compression recording processing unit 28, the display unit 30, the recording unit 32, and the like via the bus 26, and supplies the generated digital image signal 122. In this embodiment, the compression recording processing unit 28, the display unit 30, and the recording unit 32 are controlled by inputting a control signal 110 from the system control unit 16 via the bus 26.

  The compression recording processing unit 28 has a function of compressing an input digital image signal according to, for example, JPEG (Joint Photographic Experts Group) standard using orthogonal transformation. The compression recording processing unit 28 is controlled by a control signal 110 supplied from the system control unit 16, and outputs compressed image data to the recording unit 32, for example.

  The display unit 30 has a function of displaying an image based on the digital image signal 122 supplied from the signal processing unit 14, and for example, a liquid crystal display (LCD) panel or the like is used.

  The recording unit 32 has a function of recording a digital image signal. In this embodiment, the recording unit 32 includes a card interface (I / F) 74 and an information recording medium 76 as shown in FIG. The image signal compressed by the unit 28 is written to the information recording medium 76 via the card I / F 74. The information recording medium 76 may be detachable using a package containing a rotary recording body such as a memory card on which a semiconductor memory is mounted or a magneto-optical disk.

  Next, the operation of the solid-state imaging device 10 in this embodiment will be described. In the imaging apparatus 10, when an operator operates the release button of the operation unit 14 to instruct imaging, an operation signal 104 indicating an imaging instruction is supplied to the system control unit 16.

  In the system control unit 16, control signals 106 and 108 indicating an imaging instruction in accordance with the operation signal 104 are supplied to the optical system 12 and the timing generator 18, respectively. The timing generator 18 generates timing signals 112, 114, and 116 indicating a photometry instruction in response to the control signal 108, and supplies the timing signals 112, 114, and 116 to the system control unit 16, the imaging unit 20, and the preprocessing unit 22, respectively.

  In the optical system 12, incident light 102 from the object scene enters the image pickup unit 20, and an object scene image is formed on the image pickup surface. In the imaging unit 20, the signal charge on the imaging surface is read according to the timing signal 114, and an analog electric signal 118 is generated and supplied to the preprocessing unit 22. The analog electrical signal 118 in the preprocessing unit 22 is subjected to preprocessing such as CDS, GCA, and A / D conversion in accordance with the timing signal 116 to generate a digital image signal 120. The digital image signal 120 is supplied to the signal processing unit 24 and stored in the image memory 40.

  In the signal processing unit 24, the digital image signal in the image memory 40 is first subjected to offset correction processing in the offset correction unit.

Next, the digital image signal after the offset processing is subjected to a normal linear matrix operation in the first LMTX correction unit 46. In this embodiment, this digital image signal is a matrix constant α ₁ extracted from the EEPROM 48. And β ₁ are used to perform a linear matrix operation according to the above equations (1) and (2).

The digital image signal subjected to the linear matrix calculation is subjected to color shading correction by the second LMTX correction unit 50 using the linear matrix calculation. In the second LMTX correction unit 50, matrix coefficients α ₂ (x, y) and β ₂ (x, y) are extracted from the EEPROM 52, and each pixel data of the digital image signal is converted into a matrix coefficient according to the pixel position. α ₂ and β ₂ are used, and color shading correction is performed by the above formulas (1) and (2).

  Next, the digital image signal subjected to color shading correction is subjected to signal processing in the WB correction unit 54, the γ correction unit 60, the synchronization processing unit 64, and the CMTX correction unit 68, respectively.

  In this way, the digital image signal subjected to the signal processing by the signal processing unit 24 is directly or directly from the signal processing unit 24 when the system control unit 14 instructs the image recording and display to control the signal processing unit 24. The data is read out to the compression recording processing unit 28 via the bus 26. In the compression recording processing unit 28, the digital image signal 130 is subjected to compression processing and the like, recorded on the information recording medium 76 in the recording unit 32, and displayed on a liquid crystal display panel in the display unit 30.

  By the way, in the solid-state imaging device 10 according to the present invention, the light color mixture on the color filter that causes color shading is mainly the photodiodes and color filters that form the respective light receiving units 302 on the imaging surface 300 of the imaging unit 20. Further, the microlens is caused by relative displacement. The relative deviation tends to increase as the end of the imaging surface 300 is approached by using a mask pattern designed in the manufacture of the imaging unit 20.

  For example, when an image by an adjustment light source is captured and an image 402 as shown in FIG. 4 is represented, the closer to the center position of the image 402, the original color is reproduced, and the closer to the upper left, the closer to gray and the lower right. The color is reproduced with a magenta color shift. FIG. 6 shows a part of a plurality of light receiving units that capture an image near the upper left of the image 402, FIG. 7 shows a plurality of light receiving units that capture an image near the center, and a plurality of light receiving units that capture an image near the lower right. As shown in FIG.

  At this time, as shown in FIGS. 6, 7, and 8, the color filter 604 is shifted to the left with respect to the photodiode 602 and the microlens 304. When the incident light 610 from the adjustment light source is incident on the upper left light receiving portion as shown in FIG. 6, the color filter 604 is conveniently displaced, so that the incident light 610 is favorably incident on the photodiode 602, As shown in FIG. 4, the upper left of the image 402 is grayed out. However, when the light is incident on the center and lower right light receiving portions as shown in FIGS. 7 and 8, the incident light 610 passes through the filter 606 of the green pixel G and the red pixel R due to the shift of the color filters 604 and 606. As shown in FIG. 4, the image 402 changes to magenta as it approaches the lower right and is reproduced.

  For example, when the color temperature of incident light from the adjustment light source is 5600 K and an image 402 as shown in FIG. 4 is represented, red pixels R and blue pixels B for pixels on the straight line 410 from the upper left to the lower right. The output of the green pixel G is shown in FIG. On the other hand, when the color temperature of the incident light from the adjustment light source is 2300 K and an image 502 as shown in FIG. 5 is displayed, the red pixel R and the blue pixel B for the pixels on the straight line 510 from the upper left to the lower right. The output of the green pixel G is shown in FIG.

As shown in FIG. 9, at each pixel position the output of the green pixel G is, when for example a constant value G _1, red pixels R / green pixel G, and the blue pixel B / green pixel G is, the output G ₁ It is shown to increase monotonically. Thereby, gray is indicated for pixels located near the NW, and magenta is indicated for pixels located near the SE.

Maximum other hand, as shown in FIG. 10, for example, when the output of the green pixel G is a constant value G _2, a red pixel R / green pixel G is always higher than the output G _1, and the pixel located in the vicinity NW , And is shown monotonically decreasing so as to be minimum at pixels located near SE. Furthermore, the blue pixel B / green pixel G is always lower than the output G _1, and becomes a minimum at pixels located in the vicinity NW, monotonically increasing to shown to maximize the pixel located near SE. Thereby, gray is indicated for pixels near the NW, and green is indicated for pixels near the SE.

Therefore, in the solid-state imaging device 10 according to the present invention, the matrix coefficient α ₂ (x, y) used in the color shading correction by the second LMTX correction unit 50 corresponding to such a monotonically increasing or decreasing pixel output. ) And β ₂ (x, y) may be stored in EEPROM 52 as a monotonically increasing or decreasing function. At this time, it is preferable that the even-order terms of the matrix functions α ₂ (x, y) and β ₂ (x, y) are zero and a linear function is obtained. At this time, it is not necessary to have correction by the waviness term resulting from the measurement error at the time of adjustment.

Further, the matrix function α _{2 (x,} y) and β _{2 (x,} y) when storing the EEPROM 52, the matrix function α _{2 (x,} y) and β _{2 (x,} y) only coefficients that constitute the By storing the data in the EEPROM 52, the used memory capacity can be reduced. A plurality of these matrix functions α ₂ (x, y) and β ₂ (x, y) may be generated according to various zoom magnifications and aperture values.

Further, in the solid-state imaging device 10 of the present embodiment, for example, the matrix functions α ₂ (x, y) and β ₂ (x, y) are detected from the adjustment image signal based on the object scene image captured by the adjustment light source. can do.

  The signal processing unit 24 in the solid-state imaging device 10 acquires data R / Gr and B / Gb from the digital image signal 120 that is the adjusted image signal. At this time, the image indicated by the digital image signal 120 is divided into a plurality of divided areas with a predetermined number of divisions, and the data R / Gr and B / Gb of each pixel are integrated and averaged in each of the divided areas. To do. Here, the average data R / Gr and B / Gb of each divided region are fitted to (approximate) a monotone increasing function or a monotone decreasing function having a position dependency of (x, y), and R / Gr (x, y) and B / Gb (x, y) are detected and held in the signal processing unit 24.

By the way, the matrix functions α ₂ (x, y) and β ₂ (x, y) can be expressed by the following equations (3) and (4) from the above equations (1) and (2).
α ₂ (x, y) = R / Gr−R ′ / Gr (3)
β ₂ (x, y) = B / Gb−B ′ / Gb (4)
The data R ′ / Gr and B ′ / Gb in these equations (3) and (4) are converted into constants a (color temperature (K)) and b (color temperature (K)) depending on the color temperature of the light source for adjustment. As described above, the signal processing unit 24 holds the signal processing unit so as not to have (x, y) position dependency. These constants a (K) and b (K) may be detected, for example, in auto white balance (AWB) adjustment in the WB correction unit 54. Here, matrix functions α ₂ (x, y) and β ₂ (x, y) are averaged data R / Gr (x, y) and B / Gb (x, y), respectively, and a constant a (K ) And b (K) can be expressed as a monotone increasing function or a monotonic decreasing function as shown in the following equations (5) and (6).
α ₂ (x, y) = R / Gr (x, y) −a (K) (5)
β ₂ (x, y) = B / Gb (x, y) −b (K) (6)
In this way, in this embodiment, the matrix functions α ₂ (x, y) and β ₂ (x, y) can be detected based on the adjustment light source having a predetermined color temperature, and thus the desired color The matrix functions α ₂ (x, y) and β ₂ (x, y) corresponding to each temperature can be detected. In addition, the solid-state imaging device 10 of the present embodiment can detect the matrix functions α ₂ (x, y) and β ₂ (x, y) corresponding to the desired zoom magnification and aperture value, and the desired zoom magnification. And matrix functions α ₂ (x, y) and β ₂ (x, y) corresponding to the aperture value and the color temperature are stored in the EEPROM 52 connected to the second LMTX correction unit 50, and the second LMTX correction is performed. In the unit 50, the matrix functions α ₂ (x, y) and β ₂ (x, y) may be taken out and used for color shading correction.

It is a block diagram which shows one Example of the solid-state imaging device which concerns on this invention. It is a block diagram shown in detail about the signal processing part which the solid-state imaging device of the Example shown in FIG. 1 has. In the solid-state imaging device of the Example shown in FIG. 1, it is the top view which looked at some imaging surfaces from the incident work side. FIG. 2 is an example diagram of an image formed when an adjustment light source is captured in the solid-state imaging device of the embodiment shown in FIG. 1. FIG. 2 is an example diagram of an image formed when an adjustment light source is captured in the solid-state imaging device of the embodiment shown in FIG. 1. FIG. 2 is an explanatory sectional view showing a part of a configuration in which an optical system lens is provided on the imaging surface in the solid-state imaging device of the embodiment shown in FIG. 1. FIG. 2 is an explanatory sectional view showing a part of a configuration in which an optical system lens is provided on the imaging surface in the solid-state imaging device of the embodiment shown in FIG. 1. FIG. 2 is an explanatory sectional view showing a part of a configuration in which an optical system lens is provided on the imaging surface in the solid-state imaging device of the embodiment shown in FIG. 1. 2 is a graph showing output of color pixels according to pixel positions on an imaging surface in the solid-state imaging device of the embodiment shown in FIG. 1. 2 is a graph showing output of color pixels according to pixel positions on an imaging surface in the solid-state imaging device of the embodiment shown in FIG. 1.

Explanation of symbols

10 Solid-state imaging device
12 Optical system
14 Operation unit
16 System controller
18 Timing pulse generator
20 Imaging unit
22 Pretreatment section
24 Signal processor
26 Bus
28 Compression recording processor
30 Display section
32 Recording section

Claims (22)

A plurality of light receiving units arranged in rows and columns to form an imaging surface and photoelectrically converted, each of the plurality of light receiving units being provided with a filter that splits incident light into a plurality of color components An imaging means for spectrally dividing the object scene image into a first color component, a second color component, and a third color component by the filter to form an image signal;
In a solid-state imaging device including signal processing means for signal processing the image signal,
The signal processing means uses a third color component indicated by a pixel adjacent to one side of the pixel position indicating the first color component as a first correction component, and the first correction component and the first corresponding to the pixel position. Based on the color shading correction data, the first color component is subjected to color shading correction according to the pixel position, and the third color component indicated by a pixel adjacent to one side of the pixel position indicating the second color component is set to the first color component. Color shading correction means for correcting the color shading of the second color component according to the pixel position based on the second correction component and the second color shading correction data corresponding to the pixel position as the second correction component A solid-state imaging device comprising:   The solid-state imaging device according to claim 1, wherein the color shading correction unit includes a plurality of first color shading correction data and second color shading correction data corresponding to a zoom magnification and an aperture value. Solid-state imaging device.   3. The solid-state imaging device according to claim 1, wherein the color shading correction unit performs color shading correction on the first color component by a first linear matrix calculation using the first color shading correction data. A solid-state imaging device, wherein the two color components are subjected to color shading correction by a second linear matrix calculation using second color shading correction data.   4. The solid-state imaging device according to claim 3, wherein the first linear matrix calculation subtracts a value obtained by multiplying the first correction component by the first color shading correction data from the first color component, The solid-state imaging device, wherein the linear matrix calculation subtracts a value obtained by multiplying the second correction component by the second color shading correction data from the second color component.   5. The solid-state imaging device according to claim 1, wherein the first color shading correction data is monotonously increased or monotonous according to an increase in x-coordinate and y-coordinate depending on a pixel position on the imaging surface. The second color shading correction function is a first color shading correction function that decreases, and the second color shading correction data is a second that monotonously increases or decreases monotonically according to an increase in the x coordinate and the y coordinate depending on the pixel position of the imaging surface. A solid-state image pickup device having a color shading correction function.   6. The solid-state imaging device according to claim 5, wherein the first color shading correction function and the second color shading correction function are linear functions having zero even-order terms. The solid-state imaging device according to claim 5 or 6, wherein the solid-state imaging device takes in incident light from an adjustment light source having a predetermined color temperature, and forms an adjustment image signal by the imaging means.
The signal processing means includes a first correction coefficient obtained by dividing a first color component in the adjusted image signal by a first correction component in the adjusted image signal, and a first correction coefficient corresponding to the color temperature regardless of a pixel position. And a second correction coefficient obtained by dividing the second color component in the adjusted image signal by the second correction component in the adjusted image signal, and the color temperature regardless of the pixel position. A corresponding second color temperature constant,
The color shading correction unit determines a field color temperature of a light source in the scene from the image signal, and a first correction coefficient corresponding to the field color temperature from a first correction coefficient corresponding to a pixel position. A function for subtracting the color temperature coefficient is a first color shading correction function, and a function for subtracting a second color temperature coefficient corresponding to the object field color temperature from a second correction coefficient corresponding to the pixel position is a second function. A solid-state imaging device characterized by using a color shading correction function. 8. The solid-state imaging device according to claim 7, wherein the signal processing unit divides the image indicated by the adjusted image signal into a plurality of divided regions with a predetermined number of divisions, and performs a first correction for each of the plurality of divided regions. A coefficient is averaged to generate a first averaged correction coefficient, a second correction coefficient is averaged for each of the plurality of divided regions to generate a second averaged correction coefficient,
The color shading correction unit approximates a first average correction coefficient of each of the plurality of divided regions, and first increases or decreases monotonously according to the pixel position of the first color component in the image signal. And a second averaging coefficient that is monotonically increased or decreased according to the pixel position of the second color component in the image signal. A solid-state imaging device characterized by detecting a correction coefficient.   9. The solid-state imaging device according to claim 1, wherein the plurality of light receiving units are arranged in a square matrix at a constant pitch in a row direction and a column direction.   9. The solid-state imaging device according to claim 1, wherein the plurality of light receiving units are arranged at different positions in the row direction and the column direction.   11. The solid-state imaging device according to claim 1, wherein the first color component is a red component, the second color component is a blue component, and the third color component is a green component. There is a solid-state imaging device.   The solid-state imaging device according to claim 11, wherein the color arrangement pattern of the filter is a Bayer pattern.   12. The solid-state imaging device according to claim 11, wherein the color arrangement pattern of the filter is a G square lattice RB complete checkered pattern. An image pickup device having a plurality of light receiving portions arranged in rows and columns to form an image pickup surface, photoelectrically converting each of the light receiving portions, and a filter for separating incident light into a plurality of color components. An imaging process for forming an image signal by splitting the captured scene image into a first color component, a second color component, and a third color component by the filter;
In a color shading correction method including a signal processing step of signal processing the image signal,
In the signal processing step, a first color component corresponding to the first correction component and the first pixel position is set to a third color component indicated by a pixel adjacent to one side of the pixel position indicating the first color component as the first correction component. Based on the color shading correction data, the first color component is subjected to color shading correction according to the pixel position, and the third color component indicated by a pixel adjacent to one side of the pixel position indicating the second color component is set to the first color component. A color shading correction step of correcting the second color component according to the pixel position based on the second correction component and the second color shading correction data corresponding to the pixel position as the second correction component; A color shading correction method comprising:   15. The color shading correction method according to claim 14, wherein the color shading correction step includes a plurality of first color shading correction data and second color shading correction data corresponding to a zoom magnification and an aperture value. Color shading correction method.   16. The color shading correction method according to claim 14, wherein the color shading correction step performs color shading correction on the first color component by a first linear matrix calculation using first color shading correction data, A color shading correction method, wherein a second color component is subjected to color shading correction by a second linear matrix calculation using second color shading correction data.   17. The color shading correction method according to claim 16, wherein the first linear matrix calculation subtracts a first correction component obtained by multiplying the first color shading correction data from the first color component, thereby obtaining a second linear component. The matrix calculation includes subtracting a second correction component obtained by multiplying the second color shading correction data from the second color component.   The color shading correction method according to any one of claims 14 to 17, wherein the first color shading correction data is monotonically increased in accordance with an increase in x-coordinate and y-coordinate, depending on a pixel position on the imaging surface. A first color shading correction function that monotonously decreases, and the second color shading correction data is a first color that monotonously increases or monotonously decreases in accordance with an increase in the x coordinate and the y coordinate, depending on the pixel position of the imaging surface. A color shading correction method characterized by being a color shading correction function of No. 2.   19. The color shading correction method according to claim 18, wherein the first color shading correction function and the second color shading correction function are linear functions in which even-order terms are zero. The color shading correction method according to claim 18 or 19, wherein the method takes in incident light from an adjustment light source having a predetermined color temperature, and forms an adjustment image signal by the imaging step.
In the signal processing step, a first correction coefficient obtained by dividing a first color component in the adjusted image signal by a first correction component in the adjusted image signal, and a first color according to the color temperature regardless of a pixel position. And a second correction coefficient obtained by dividing the second color component in the adjusted image signal by the second correction component in the adjusted image signal, and the color temperature regardless of the pixel position. A corresponding second color temperature coefficient is detected,
In the color shading correction step, a field color temperature of a light source in the scene is determined from the image signal, and a first correction coefficient corresponding to a pixel position is used to determine a first color corresponding to the field color temperature. A function for subtracting the color temperature coefficient is a first color shading correction function, and a function for subtracting a second color temperature coefficient corresponding to the object field color temperature from a second correction coefficient corresponding to the pixel position is a second function. A color shading correction method, characterized in that a color shading correction function is used. 21. The color shading correction method according to claim 20, wherein the signal processing step divides the image indicated by the adjusted image signal into a plurality of divided regions by a predetermined number of divisions, and the first division is performed for each of the plurality of divided regions. A correction coefficient is averaged to generate a first average correction coefficient, a second correction coefficient is averaged for each of the plurality of divided regions to generate a second average correction coefficient,
The color shading correction step approximates the first average correction coefficient of each of the plurality of divided regions, and first increases or decreases monotonously according to the pixel position of the first color component in the image signal. And a second averaging coefficient that is monotonically increased or decreased according to the pixel position of the second color component in the image signal. A color shading correction method characterized by detecting a correction coefficient.   The color shading correction method according to any one of claims 14 to 21, wherein the first color component is a red component, the second color component is a blue component, and the third color component is a green component. A color shading correction method characterized by being:

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