One-chip color camera capable of restricting unwanted false color signal

The present invention relates to a color camera, in particular, solid-state imaging including photoelectric conversion elements arranged in an array, corresponding to color filters arranged in an array by a color difference sequential method. The present invention relates to a single-panel color camera having a color separation circuit for processing a signal from a device.

[0002] A CCD (Charge Coupled Device), which is widely used as an imaging device in a color camera at present, simply changes the amplitude of an output signal according to the brightness and darkness of the received light, and outputs the CCD (Charge Coupled Device). The signal does not contain color information. Therefore, in order to obtain color information, it is necessary to take some measures such as filtering the light incident on the CCD by using optical means.

[0003] In a home-use color camera, a so-called single-plate method of extracting three primary color signals from a single CCD is adopted, and a so-called simultaneous color imaging method using a color filter array on the light receiving surface side of the CCD. Has been adopted.

[Structure of Interline Transfer CCD] FIG. 10 is a schematic block diagram showing a configuration of an interline transfer CCD10 that is generally used as a configuration of a CCD in a home color camera.

[0005] The interline transfer CCD 10 includes a photosensitive unit 12 composed of pn junction photodiodes arranged in an array, a transfer unit 14 including an analog shift register composed of the CCD, and a charge transferred by the transfer unit 14. It includes a horizontal transfer register 16 that transfers and outputs a signal obtained by converting a signal charge that is sequentially transferred into a voltage in the horizontal direction.

[0006] In FIG. 10, for the sake of simplicity, the pn junction type photodiode has a configuration in which three pixels are arranged both vertically and horizontally. In fact, in a CCD used for a color camera, for example, photodiodes corresponding to 500 pixels in the vertical direction and 500 to 800 pixels in the horizontal direction are arranged in an array.

[0007] Next, the operation will be briefly described. When light enters the photodiode, an electric charge is generated and accumulated in the diode. Next, by applying a predetermined voltage to the shift gate, the accumulated charges are simultaneously transferred to the analog shift register 14. The CCD analog shift register 14 has a clock pulse voltage φ._V1, φ_V2, φ_V3Is applied, the electric charge is sequentially transferred to the horizontal transfer register 16. In the horizontal transfer register 16, the horizontal drive signal φ given from the outside after converting the transmitted signal charge into a voltage._H1, φ_H2, φ_H3It is driven by and is sequentially output to the outside as an imaging signal output.

[Drive method of interline transfer CCD] As a drive method of the interline transfer CCD, there are generally two modes, a frame storage method and a field storage method. In a color camera, a frame storage method premised on an all-pixel readout operation may be used even if the color filter array of the color difference sequential method is supported.

[0009] In the following, the case where the interline transfer CCD is operating in the frame storage mode in which it can be read out for each pixel will be considered.

[Color Difference Signal Separation Method] FIG. 11 is a schematic diagram showing a configuration of a color filter array arranged by a color difference sequential method.

As shown in FIG. 11, in the color filter of the color difference sequential method, magenta (hereinafter, represented by Mg), green (hereinafter, represented by G), cyan (hereinafter, represented by Cy), and yellow are used as color filters. The color filters (hereinafter referred to as Ye) are arranged in a mosaic pattern.

[0012] Here, since the so-called additive color method is established in the mixing of light colors, Mg, Ye, which have a complementary color relationship with the three primary colors red (R), green (G), and blue (B). The following relationship holds with, Cy.

[0013] Mg = R + B ... (1) Ye = R + G ... (2) Cy = B + G ... (3) Therefore, as the color of the color filter, the above Mg, G, By using Ye and Cy, it is possible to make the intensity of the G signal, which has a large specific gravity with respect to the luminance signal among the three primary colors R, G, and B, larger than that of the R signal and the B signal.

In the example shown in FIG. 11, the array portion of 4 rows and 4 columns is extracted from the color filter array of the color difference sequential method. In the odd-numbered rows (x = 1, 3), the G color filter and the Mg color filter are arranged alternately in the horizontal direction (y direction).

On the other hand, in the even-numbered rows (x = 0, 2), the Ye color filter and the Cy color filter are alternately arranged in the horizontal direction.

[0016] FIG. 12 shows an array of color filters when the array of color filters of 4 rows and 4 columns shown in FIG. 11 is deviated by one pixel in the horizontal direction.

[0017] For example, when the output from the photoelectric conversion element is sequentially read in the y direction, the output from the photoelectric conversion element for 4 rows and 4 columns read from the CCD at a certain time is from the color filter array shown in FIG. The case corresponding to the output of and the case corresponding to the output from the color filter array shown in FIG. 12 are alternately repeated. In the color difference sequential color filter array as shown in FIG. 11, the arbitrary 4-by-4 color filter array is the case shown in FIG. 11 or 12, and the arrangement of FIG. 11 or 12 is x, respectively. It will be one of four arrangements including the case where it is shifted by one pixel in the direction.

[0018] FIG. 13 is a conceptual diagram for explaining a conventional color separation method. In FIG. 13, 2 rows and 2 columns are extracted from the 4 rows and 4 columns array shown in FIG. In the conventional color separation method, among the signals obtained by reading out all the pixels from the CCD, the luminance signal Y about the center position of the 2 rows and 2 columns pixels is selected from the signals corresponding to the 2 rows and 2 columns pixels. , The first color difference signal Cb and the second color difference signal Cr are generated.

Here, the luminance signal Y, the first color difference signal Cb, and the second color difference signal Cr are signals expressed by the following equations when the signal intensities corresponding to the three primary colors are R, G, and B, respectively. Is.

【0020】<img file="JP3649841B2_D0001.tif" />Therefore, in principle, the luminance signal Y, the first color difference signal Cb, and the second color difference signal Cr can be obtained as long as the signals from the two-row, two-column photoelectric conversion element shown in FIG. 13 can be obtained. Based on this, it is also possible to separate the three primary color signals by the following calculation.

[0021] G = (2Y-2Cr-2Cb) / 10 ... (7) R = (Y + 4Cr-Cb) / 10 ... (8) B = (Y-Cr + 4Cb) / 10 .. (9) [0022] [Problems to be Solved by the Invention] However, the color separation method as described above has the problems described below.

FIG. 14 shows the horizontal frequency characteristics of the output signals Ye + G, Cy + Mg, G + Cy, Ye + Mg when the conventional color separation method as shown in FIG. 13 is realized by a digital filter. It is a figure which shows.

[0024] In FIG. 13, assuming that the signals from the CCD are read out sequentially in the y direction, the signals Ye + G and Cy + Mg are generated from the signals sampled at the same time point, whereas the signals are generated. For G + Cy and Ye + Mg, it is necessary to hold the signal for one sampling time.

Therefore, the gains of the signals Ye + G and Cy + Mg have no frequency dependence, whereas the gains of the signals G + Cy and Ye + Mg decrease monotonically as they approach the Nyquist frequency. Shows the characteristics.

[0026] If the horizontal frequency characteristics of the signals that generate the first and second color difference signals Cb and Cr are different, a false color signal is generated and the image quality is impaired. there were.

[0027] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to align the bands of each color component signal, suppress the generation of false color signals, and improve the image quality. It is to provide a single-panel color camera capable of doing so.

[0028] Another object of the present invention is to provide a single-panel color camera capable of suppressing a decrease in resolution even when the bands of the respective color signal components are aligned.

[Means for Solving the Problems] The single-plate color camera according to claim 1 includes solid-state imaging means in which photoelectric conversion elements corresponding to pixels are arranged in an array. On the light receiving surface side, a color filter array in which color filters are arranged in a mosaic pattern with respect to the corresponding photoelectric conversion element is included, and 4 of the color filter arrays correspond to any 4 rows and 4 columns of pixels. The even-th row of rows and four columns has an alternating green filter and the first complementary color filter that corresponds to magenta, and the odd-th row of rows and four columns corresponds to the alternating yellow. It has a second complementary color filter and a third complementary color filter corresponding to cyan, and outputs the output of the solid-state imaging means.<u style="single">Sequentially every 4 lines</u>In response, it is further provided with color separating means for generating color data corresponding to the center position of the pixel of 4 rows and 4 columns, and the color separating means is provided for green and each of the first to third complementary colors.<u style="single">Receive sequentially</u>From the color interpolation means and the color interpolation means, which output the weighted averaged output from the photoelectric conversion element in which the corresponding color filter is arranged, among the outputs from the plurality of photoelectric conversion elements corresponding to the pixels of 4 rows and 4 columns. Including a first arithmetic means that receives the output of and separates the color data corresponding to the center position.<u style="single">、</u>The output from the photoelectric conversion element corresponding to the pixels of 4 rows and 4 columns is set to D (x, y) (x = 0 to 3, y = 0 to 3), and corresponds to D (x, y) in the weighted averaging process. When the weighting coefficient to be used is w (x, y)<u style="single">color</u>The interpolation means is the first weighted averaging process in which w (1,2) = 2, w = (1,0) = 1 and w (3,2) = 1 as the first weighting coefficient, and the second. The second weighted average processing with w (1,1) = 2, w = (3,1) = 1 and w (1,3) = 1 as the weighting coefficient, and w (2) as the third weighting coefficient. , 2) = 2, w = (0,2) = 1 and w (2,0) = 1 as the third weighted averaging process and the fourth weighting factor, w (2,1) = 2, w Fourth weighted average with = (2,3) = 1 and w (0,1) = 1<u style="single">Receive the reason sequentially</u>Depending on the array of color filters corresponding to the 4 rows and 4 columns of pixels,<u style="single">For green and the first to third complementary colors, respectively</u>Run.

[0032] Claim<u style="single">2</u>The single-panel color camera described is claimed.<u style="single">1</u>In the configuration of the single-panel color camera described,<u style="single">The color separation means outputs a luminance signal by adding the outputs from the photoelectric conversion elements of 2 rows and 2 columns surrounding the center position among the outputs from the photoelectric conversion elements corresponding to the pixels of 4 rows and 4 columns. Including arithmetic means of</u>。

[0033] The single-panel color camera according to claim 3 is claimed.<u style="single">2</u>In the configuration of the single-panel color camera described, among the outputs from the photoelectric conversion elements corresponding to the pixels of 4 rows and 4 columns, D (0,1), D (0,2), D (1,1) and D The first signal, which is the sum of (1,2), and the second signal, which is the sum of D (1,0), D (1,1), D (2,0), and D (2,1). And the third signal, which is the sum of D (2,1), D (2,2), D (3,1) and D (3,2), and D (1,2), D (1,2). 3) Aperture signal generation means that outputs an aperture signal based on a fourth signal that is the sum of D (2,2) and D (2,3) and a luminance signal, and an aperture according to the aperture signal. Further provided with a correction means for performing correction.

[Embodiment of the Invention] FIG. 1 shows a color separation circuit from an optical system 2 connecting an optical image to be imaged to CCD10, which is an image pickup device, in the configuration of a single-plate color camera according to the embodiment of the present invention. It is a schematic block diagram which shows the structure of the color signal processing system 1000 including up to 100.

The color signal processing system 1000 has an optical system 2 that receives light to be imaged, a CCD10 that converts an optical image formed by the optical system 2 into an electric signal, and an all-pixel independent read drive for the CCD10. The drive circuit 40 to be performed, the correlated double sampling circuit (hereinafter referred to as the CDS circuit) 44 that receives the output signal of the CCD10 and removes noise from the image pickup signal by a well-known method, and the auto that amplifies the output of the CDS circuit 44. Gain control circuit (hereinafter referred to as AGC circuit) 46, A / D conversion circuit 48 that converts the output of AGC circuit 46 into a digital signal, and even line output signal and odd number of CCD10 from A / D conversion circuit 48. It includes a frame memory 50 that holds the output signal of the line in a nested manner, and a control circuit 42 that receives the CCD drive signal from the drive circuit 40 and outputs the horizontal address HA and vertical address VA of the pixel from which the output signal is read.

[0036] Further, the color signal processing system 1000 further delays the first input signal from the frame memory 50 by one scanning line time and outputs the second input signal, and the scanning line delayer 18 and the second input signal. A scanning line delayer 20 that delays the third input signal by one scanning line time and outputs a third input signal, and a scanning line delayer 22 that delays the third input signal by one scanning line time and outputs a fourth input signal. , The color separation circuit 100, which is a two-dimensional non-circulating digital filter that receives the first to fourth input signals and outputs the brightness signal Y, the first color difference signal Cb, and the second color difference signal Cr, is included.

The color separation circuit 100 sequentially receives the first to fourth input signals in parallel, and the data from the pixels of 4 rows and 4 columns (in the arrangement of the color filter of the CCD from which the signal was read at that time). Correspondingly, it includes green, yellow, cyan, and magenta color signals.) And receives signals from the two-dimensional register array 30 and receives green, yellow, cyan, and magenta color signals. By performing weighted averaging processing for each, the interpolation processing circuit 34 that interpolates and generates the color signal corresponding to the center position of the pixels of 4 rows and 4 columns, and the color difference signals Cb and Cr are generated from the color signal generated by the interpolation. The color difference signal generation circuit 36, the brightness signal generation circuit 32 that receives the signals from the two-dimensional register array 30 and generates the brightness signal Y, and the aperture signal AP that receives the signals from the brightness signal Y and the two-dimensional register array 30. Includes an aperture signal generation circuit 38 that outputs.

[0038] Here, the image pickup lens included in the optical system 2 usually includes a variable mechanism such as an aperture, a focus, and a zoom.

[0039] The color signal processing system 1000 further includes an aperture correction circuit (not shown) that performs aperture correction (contour enhancement processing) according to the aperture signal.

[0040] In the above configuration, the first to fourth types of input signals correspond to the imaging signals of four scanning line segments (four lines), and these signals are grouped into four lines and one color separation circuit. It will be entered in 100.

[0041] In this way, the FIR (Finite Impulse Response) filter is realized by the color separation circuit 100 and the three scan line delayers 18 to 22.

[Interpolation processing and color separation processing] FIG. 2 is a schematic diagram for explaining the interpolation processing operation in the present embodiment. FIG. 2 (a) shows an example of an array of color filter arrays of 4 rows and 4 columns, and FIG. 2 (b) shows the weighting coefficient during interpolation processing in the case of the array of magenta color filters of FIG. 2 (a). 2 (c) shows the arrangement of the weighting coefficients during the interpolation process in the case of the array of green filters in FIG. 2 (a), and FIG. 2 (d) shows the arrangement of the weighting coefficients in FIG. 2 (a). The arrangement of the weighting coefficient during the interpolation process in the case of the array of cyan color filters is shown, and Fig. 2 (e) shows the arrangement of the weighting coefficient during the interpolation process in the case of the array of the yellow filter in Fig. 2 (a). Shown.

That is, in the present embodiment, the magenta color signal component, the green signal component, the cyan color signal component, and the yellow signal component corresponding to the center positions of the pixels of 4 rows and 4 columns are subjected to the following weighted average interpolation processing. To generate.

[0044] Mg = 2 × Mg11 + Mg13 + Mg31 ... (10) G = 2 × G12 + G10 + G32 ... (11) Cy = 2 × Cy21 + Cy01 + Cy23 ... (12) Ye = 2 × Ye22 + Ye02 + Ye20 ... (13) As explained in Fig. 11 and Fig. 12, there are four types of color filter arrays corresponding to pixels in 4 rows and 4 columns, except for Fig. 2 (a). In the case of an array, the array of weighted average weighting coefficients for each color filter also corresponds to the other arrays in FIGS. 2 (b) to 2 (e).

[0045] As described above, in the present embodiment, the CCD 10 performs an all-pixel independent read operation. That is, as shown in FIG. 2A, for the 0th line in the vertical direction (x direction), the color filters Ye and Cy are alternately arranged in the horizontal direction (y direction). , The read signal from CCD10 is a signal in which Ye and Cy are alternately output for the scanning line corresponding to this line. For the next first line (corresponding to x = 1), the signal Mg and the signal G are output alternately.

[0046] FIG. 3 is a block diagram showing in more detail the configurations of the scanning line delay circuits 18, 20, 22 and the two-dimensional register array 30 that receive the read signal from the CCD 10, among the configurations shown in FIG. is there.

The two-dimensional register array 30 receives the output from the frame memory 50 holding the output signal from the A / D converter 16 and outputs the signal d01 with a delay of one clock, and the register 302 and the signal d01. It includes a register 302 that receives and outputs the signal d01 with a delay of one clock.

[0048] The two-dimensional array register 30 further receives the signal d10 from the scanning line delayer 18 and delays by one clock to output the signal d11, and receives the signal d11 and delays by one clock. The signal 308 that outputs the signal d12, the register 310 that receives the signal d12 and outputs the signal d13 with a delay of 1 clock, and the signal d20 from the scanning line delayer 20 are received and the signal is delayed by 1 clock. The register 312 that outputs d21, the register 314 that receives the signal d21 and outputs the signal d22 with a delay of 1 clock, the register 316 that receives the signal d22 and outputs the signal d23 with a delay of 1 clock, and the scanning line. It includes a register 318 that receives the signal from the delay device 22 and outputs the signal d31 with a delay of one clock, and a register 320 that receives the signal d31 and outputs the signal d32 with a delay of one clock.

That is, the signals from the CCD 10 read serially by the two-dimensional register array 30 are converted so that the signals from the photoelectric conversion elements corresponding to the pixels of 4 rows and 4 columns are output in parallel. To.

That is, the above-mentioned signals d01 to d32 correspond to the output signals from the photoelectric conversion element corresponding to the pixels (x, y) in the CCD10 represented by the symbol dxy.

FIG. 4 is a block diagram showing the configuration of the interpolation processing circuit 34 shown in FIG. 1 in more detail.

[0052] The interpolation processing circuit 34 has an interpolation calculation unit 342 that receives signals d12, d10, d32 and outputs a first interpolation signal, and interpolation that receives signals d11, d13, d31 and outputs a second interpolation signal. The calculation unit 344, the interpolation calculation unit 346 that receives the signals d21, d01, d23 and outputs the third interpolation signal, and the interpolation calculation unit 348 that receives the signals d22, d02, d20 and outputs the fourth interpolation signal. , The selection circuit 350, which is controlled by the control circuit 42 and outputs each of the first to fourth interpolated signals as a green signal G, a cyan signal Cy, a magenta color signal Mg, and a yellow signal Ye.

[0053] Here, the interpolation calculation unit 342 receives the signal d12 and doubles and outputs the multiplier 3422, the adder 3424 which outputs the addition result of the signal d10 and the signal d32, and the adder 3424 and the multiplier. It includes an adder 3426 that outputs the addition result of 3422 as a first interpolation signal. The configurations of the interpolation calculation units 344, 346 and 348 are basically the same as the configurations of the interpolation calculation unit 342 except that the received signals are different.

[0054] Therefore, when the arrangement of the color filter is shown in FIG. 2 (a), the interpolation calculation unit 342 corresponds to performing the weighted averaging process by the arrangement of the weighted coefficients shown in FIG. 2 (c), and performs interpolation. The calculation unit 344 performs the weighted averaging process by arranging the weighted coefficients shown in FIG. 2 (b), and the interpolation calculation unit 346 performs the weighted averaging process by arranging the weighted coefficients shown in FIG. 2 (d). In particular, the interpolation calculation unit 348 corresponds to performing the weighted averaging process by arranging the weighted coefficients shown in FIG. 2 (e).

The selection circuit 350 has a th-order according to the least significant bit h-addLSB of the horizontal address HA and the least significant bit v-addLSB of the vertical address VA indicating the current read position from the CCD 10 output from the control circuit 42. The first to fourth interpolated signals are output by switching the association between the green signal G, the cyan signal Cy, the magenta color signal Mg, and the yellow signal Ye.

[0056] For example, when the color filter is shown in FIG. 2A, the first interpolated signal is the green signal G, the second interpolated signal is the magenta color signal Mg, and the third interpolated signal is the cyan signal. Since the fourth interpolated signal corresponds to Cy and the yellow signal Ye, respectively, the selection circuit 350 outputs a signal so as to have such a correspondence.

[0057] When the arrangement of the color filters corresponding to the pixels of 4 rows and 4 columns for reading the signal changes, the selection circuit 350 changes the above-mentioned association accordingly.

By the operation of the above interpolation processing circuit 34, the read signal from the photoelectric conversion element corresponding to the pixels of 4 rows and 4 columns is obtained for each of the green signal G, the cyan color signal Cy, the magenta color signal Mg, and the yellow signal Ye. By a predetermined weighted averaging process for the above, a signal corresponding to the center position of the pixels of 4 rows and 4 columns is generated.

FIG. 5 is a diagram showing the frequency characteristics of the output signals Ye + G, Cy + Mg, G + Cy, Ye + Mg when the interpolation processing is realized by the digital filter as shown in FIG. It is a figure to be contrasted with 14.

By interpolation processing, the frequency characteristics of the output signals Ye + G, Cy + Mg, G + Cy, Ye + Mg are aligned to around 1/2 Nyquist frequency. Therefore, when color separation processing is performed based on these signals to obtain color difference signals Cb and Cr, it is possible to suppress the occurrence of false colors and improve the image quality.

[0061] In the above description, the weighted average of the arrangement of the weighting coefficients shown in FIGS. 2 (b) to 2 (e) is applied to the output signal from the photoelectric conversion element corresponding to the pixels of 4 rows and 4 columns. Although the case where the interpolation process is performed has been described, the present invention is not limited to such a case. For example, the pixel to be interpolated may be, more generally, a pixel of k rows and k columns, where k is an even number. Also, regarding the arrangement of the weighting coefficients, the arrangement of the weighting coefficients corresponding to each of the four color signals, that is, the green signal, the cyan color signal, the magenta color signal, and the yellow signal, is 90 degrees to the center position. It suffices if the relationship is rotated.

[0062] Further, the color signal is not necessarily limited to the green signal, the cyan signal, the magenta color signal, and the yellow signal, and is used in a combination of other color signals, for example, a color filter of a frame color difference sequential method. It can also be applied to a combination of YM, CG, YG, and CM.

[0063] FIG. 6 is a block diagram showing the configuration of the color difference signal generation circuit 36 shown in FIG. 1 in more detail.

[0064] With reference to FIG. 6, the color difference signal generation circuit 36 receives and adds an adder 362 that receives and adds a yellow signal Ye and a magenda signal Mg, and an adder 368 that receives and adds a green signal G and a cyan signal Cy. It includes an adder 374 that multiplies the output of the adder 368 by -1, and an adder 376 that adds the output of the adder 362 and the output of the multiplier 374 to output the signal Cr.

[0065] The color difference signal generation circuit 36 further adds an adder 364 that receives and adds a magenta signal Mg and a cyan color signal Cy, and an adder 366 that receives and adds a green signal G and a yellow signal Ye. It includes a multiplier 372 that multiplies the output of device 366 by -1, and an adder 370 that adds the output of adder 364 and the output of multiplier 372 to output signal Cb.

That is, the color difference signal generation circuit 36 generates color difference signals Cb and Cr from the green signal G, the cyan color signal Cy, the magenta color signal Mg, and the yellow signal Ye by the following arithmetic processing.

【0067】<img file="JP3649841B2_D0002.tif" />[Brightness signal generation and aperture signal generation] Here, the brightness signal is configured to be generated from the green signal G, the cyan color signal Cy, the magenta color signal Mg, and the yellow signal Ye obtained by the above interpolation processing by the following calculation. It is also possible to.

【0068】<img file="JP3649841B2_D0003.tif" />However, as the luminance signal, among the signals from the photoelectric conversion element corresponding to the pixels of 4 rows and 4 columns, the signal corresponding to the pixels of 2 rows and 2 columns surrounding the center position is directly calculated based on the above equation. It is also possible to have a configuration to generate. That is, in this case, the luminance signal Y is generated by the same method as the conventional color separation method described with reference to FIG.

[0069] Although it is possible to suppress the occurrence of false colors by performing the interpolation processing, the resolution is lowered by the interpolation at the same time. Since the sensitivity of the human eye is higher with respect to the luminance information than the color information, it is possible to suppress the decrease in resolution felt by humans by directly using the signal without interpolation processing for the luminance signal Y. Become.

[0070] This also applies to, for example, the generation of an aperture signal for performing aperture correction. That is, it is desirable that the luminance signal, which is the basis for generating the aperture signal, has as high a resolution as possible, and if the signal after the interpolation processing or the like is used, the resolution will also be lowered.

FIG. 7 is a diagram for explaining the generation of the luminance signal Y and the first generation process of the aperture signal AP as described above. Further, FIG. 8 is a diagram showing a second generation process of the aperture signal AP.

[0072] With reference to FIG. 7, first, the signals Y01, Y10, Y11, Y12, and Y21 are generated by the operations shown below.

[0073] Y01 = Ye02 + Cy01 + Mg11 + G12 ... (17) Y10 = Ye20 + Cy21 + Mg11 + G10 ... (18) Y11 = Ye22 + Cy21 + Mg11 + G12 ... (19) Y12 = Ye22 + Cy23 + Mg13 + G12 ... (20) Y21 = Ye22 + Cy21 + Mg31 + G32 ... (21) That is, Y11 corresponds to the luminance signal Y. Further, the signals Y01, Y10, Y12, and Y21 are from the photoelectric conversion element corresponding to the 2 rows and 2 columns pixels including 2 of the central 2 rows and 2 columns pixels used to generate Y11, respectively. It will be generated from the signal.

Subsequently, with reference to FIG. 8, the aperture signal AP is generated by the calculation according to the following equation based on the signals Y01, Y10, Y11, Y12, and Y21 generated as described above.

AP = 4 × Y11-Y01-Y10-Y12-Y21 ... (22) FIG. 9 is a schematic for explaining the configuration of the luminance signal generation circuit 32 and the aperture signal 38 shown in FIG. 1 in more detail. It is a figure.

[0076] The brightness signal generation circuit 32 receives and adds the adder 322 that receives and adds the signals d11 and d21, the adder 324 that receives and adds the signals d12 and d22, and the outputs of the adders 322 and 324. Includes an adder 326 that outputs the brightness signal Y (Y11).

The aperture signal generation circuit 38 receives and adds the adder 382 that receives and adds the signals d01 and d11, the adder 386 that receives and adds the signals d02 and d12, and the outputs of the adders 382 and 386. Adder 384, adder 388 that receives and adds signals d10 and d20, adder 392 that receives and adds the output of adder 388 and adder 322 in the brightness signal generation circuit 32, and adders 384 and 392. Includes adder 390 and which adds the output of.

The aperture signal generation circuit 38 further receives the outputs of the adder 398, which receives and adds the signals d21 and d31, the adder 402, which receives and adds the signals d22 and d32, and the adders 398 and 402. Adder 400 to add, adder 396 to receive and add signals d13 and d23, adder 394 to receive and add from the output of adder 396 and adder 324 in the brightness signal generation circuit 32, and adder 394 Adder 404 to add the outputs of and 400, adder 406 to add the outputs of adders 390 and 404, multiplyer 410 to multiply the output of adder 406 by -1, and the brightness signals Y and 4. It includes an adder 408 to multiply and an adder 412 that receives and adds the outputs of the multipliers 408 and 410 and outputs a signal AP.

That is, the luminance signal generation circuit 32 outputs the luminance signal Y by the calculation shown in the equation (19), and the aperture signal generation circuit 38 outputs the aperture signal AP by the arithmetic shown in the equations (17) to (22). Is generated and output.

[0080] With the above configuration, when generating the aperture signal AP, the photoelectric conversion element corresponding to the pixels of 2 rows and 2 columns surrounding the center position of 4 rows and 4 columns is used. Since the luminance signal Y based on the signal of is used, it is possible to suppress the decrease in resolution due to the interpolation processing.

[Effects of the Invention] As described above, according to the present invention, the signals Ye + G and Cy + Mg are obtained by aligning the bands of each color component by performing interpolation processing before performing color separation processing. Since the bands of the signals G + Cy and Ye + Mg are very close to the 1/2 Nyquist frequency, it is possible to significantly reduce the color false signal near the 1/2 Nyquist frequency as a result. Further, for the generation of the aperture signal, it is possible to suppress the reduction in resolution due to the interpolation processing.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a schematic block diagram showing a configuration of a color signal processing system 1000 of the present invention.

2A and 2B are schematic views for explaining the interpolation process of the present invention, FIG. 2A is an array of color filter arrays of a color difference sequential method, and FIGS. 2B to 2E are color signals. It is a schematic diagram for demonstrating the arrangement of the weighting coefficient at the time of the interpolation processing with respect to a component.

FIG. 3 is a block diagram showing a configuration of a two-dimensional register array 30 of the color signal processing system 1000 shown in FIG.

FIG. 4 is a block diagram showing a configuration of an interpolation processing circuit 34 of the color signal processing system 1000 shown in FIG.

FIG. 5 is a diagram showing frequency characteristics of the color signal of the present invention.

FIG. 6 is a block diagram showing a configuration of a color separation circuit 36 of the color signal processing system 1000 shown in FIG.

FIG. 7 is a first schematic diagram illustrating a process of generating an aperture signal.

FIG. 8 is a second schematic diagram illustrating a process of generating an aperture signal.

9 is a block diagram showing a configuration of a luminance signal generation circuit 32 and an aperture signal generation circuit 38 of the color signal processing system 1000 shown in FIG. 1. FIG.

FIG. 10 is a schematic block diagram showing a configuration of CCD10.

FIG. 11 is a schematic diagram showing an example of an array of 4-by-4 color filters in a color filter array of a color difference sequential method.

FIG. 12 is a schematic diagram showing another example of a 4-by-4 color filter array in a color-difference sequential color filter array.

FIG. 13 is a conceptual diagram illustrating a conventional color separation method.

FIG. 14 is a diagram showing a frequency characteristic of an output signal of a conventional color separation method.

[Code description] 10 CCD12 Photosensitive unit 14 Transfer unit 16 Horizontal transfer registers 18, 20, 22 Scanning line delayer 30 Two-dimensional register array 32 Brightness signal generation circuit 34 Interpolation processing circuit 36 Color difference signal generation circuit 38 Aperture signal generation circuit 40 Drive circuit 42 Control circuit 44 CDS circuit 46 AGC circuit 48 A / D conversion circuit 100 Color separation circuit