JPH11313338A - Signal processor and photographing signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain signal processing to obtain an image that is not deteriorated without the need for a delay circuit which matches a time between a chrominance processing system and a luminance processing system. SOLUTION: A color difference signal obtained by applying matrix conversion to an RGB signal processed by a color suppression circuit 5 placed before a gamma correction circuit of a color-A/D converter system 5 1 is used to conduct correction of luminance and color difference signals before an aperture correction circuit 10 and a gamma correction circuit 11 of a luminance processing system. Or the color suppression circuit may process a complementary color signal from a color interpolation circuit 3 or a digital signal from an A/D converter circuit 2. Or a color correction circuit may be used by which saturated pixels are supplemented by pixels in a same color around pixels of a saturated CCD in place of the color suppression circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a signal processing apparatus and a signal processing method for an image pickup output for converting a subject image into an image signal and processing it into a luminance signal and a color difference signal.

[0002]

2. Description of the Related Art Conventionally, a subject image is converted into an image signal,
In a signal processing device of an imaging output for processing a luminance signal and a color difference signal, the processing is performed according to a signal processing block as shown in FIG.

The received image of the subject image is converted into an electric signal by the CCD 1. The video electric signal is converted from an analog signal to a digital signal by the A / D conversion circuit 2.
The converted digital signal is processed separately in a color processing system 51 and a luminance signal system 52.

In a color processing system 51, a digital signal output from an A / D conversion circuit 2 is transmitted to a color interpolation circuit 3 by a CCD 1.
Yellow (Ye), cyan (Cy),
It is output as four complementary color signals consisting of magenta (Mz) and green (G). The complementary color signal is output from the matrix circuit 4
And red (R), green (G) and blue (B)
, And output as RGB signals. Next, the RGB signals are passed through the gamma correction circuit 6.
It is matched with a video signal to be displayed on a TV monitor or the like, and is converted into a color difference signal by a color difference matrix circuit 7. Thereafter, the color suppression circuit 20 removes the color noise of the low-luminance portion from the color difference signal, and also removes the saturated CCD.
The color of the pixel including the one high-brightness color is suppressed.

The color signal band is limited by a series of processes of the color processing system 51 such as the color interpolation circuit 3. That is,
The color signal in the digital signal output from the A / D conversion circuit 2 is subjected to a process of limiting the band by the color processing system 51, and is converted into a color difference signal.

On the other hand, in the luminance processing system 52, the digital signal output from the A / D conversion circuit 2 is subjected to a color carrier removal circuit 8 to remove a color carrier component, and becomes a substantially unprocessed luminance signal. Next, the aperture correction circuit 10 raises the characteristics of the luminance signal in the high frequency region. Further, the gamma correction is performed in the gamma correction circuit 11 as in the color processing system 51. After that, the luminance / color difference correction circuit 9 corrects the balance of the color components in the luminance signal using the color difference signal color-suppressed by the color suppression circuit 20 of the color processing system 51, and outputs a final luminance signal. You.

[0007]

The color temperature of a subject is CC
If the color temperature of the D color filter is significantly deviated from the preset color temperature, not only the color reproducibility but also the balance of the color components in the luminance signal may be lost. For this reason, in the signal processing device of the conventional image pickup output, the processing is performed by the color suppression circuit 20 which removes the color noise of the low luminance portion and suppresses the color of the pixel including the saturated high luminance color of the CCD 1. Luminance and color difference correction for correcting the balance of color components in the luminance signal is performed using the color difference signal.

However, as described above, in the conventional image output signal processing device, the processing of the color difference signal by the color suppression circuit 20 is performed at the final stage of the color processing system 51. Performed in the last stage of system 52,
The output timings of the color processing system 51 and the luminance processing system 52 are synchronized. Therefore, when the luminance signal is subjected to aperture correction or the like in the luminance processing system 52, the color components in the luminance signal may be out of balance. In some cases.

Further, the color processing system 51 of the conventional signal processing device
If the luminance processing system 52 performs the luminance / color difference correction before performing the aperture correction or the gamma correction in the luminance processing system 52, the color suppression circuit 20 may be used because the output timings of the color processing system 51 and the luminance processing system 52 are matched. In this case, the luminance signal must be corrected with the signal that has not been processed in this case. In this case, the luminance signal is processed in a state that includes the color noise of the low luminance portion and the high luminance color of the saturated CCD1 pixel. When reproducing the subject image on a TV monitor, etc., the saturated CCD1
In some cases, the image captured by the pixel markedly deteriorates.

Further, the color processing system 5 of the conventional signal processing device
1 using the color difference signal processed by the color suppression circuit 20 and the aperture correction circuit 1 of the luminance processing system 52.
If the luminance signal is corrected for luminance and color difference before 0, the color processing system 5
1 and the luminance processing system 52, that is, the luminance signal and the color suppression circuit 2 before the aperture correction circuit 10.
In order to match the timing of the chrominance signal processed with 0, many extra delay circuits are required in the luminance processing system 52,
The circuit scale becomes large.

The present invention has been made in view of the above circumstances, and the present invention obtains an image that has not deteriorated without requiring a delay circuit for adjusting the time between a color processing system and a luminance processing system. It is an object of the present invention to provide a signal processing device and a signal processing method for imaging capable of performing signal processing.

[0012]

According to a first aspect of the present invention, there is provided a signal processing apparatus for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal. An imager for converting the subject image into the image signal and storing the image signal; a detector for detecting a low-brightness portion or a high-brightness portion of the image signal stored by the imager; Color level control means for controlling the level of the color signal of the low luminance portion or the high luminance portion detected by the means, and limiting the band of the color signal of the image signal, and Gamma correction, a color processing unit that processes the gamma-corrected color signal into a color difference signal, and a luminance / color difference correction unit that controls a color component balance of the luminance signal, wherein the color level control unit is The color signal processing in the path of the processing means is provided before the gamma correction, and controlling the color components balance by the color level control means and the luminance and color difference correction means controlled color signal by.

According to a second aspect of the present invention, there is provided a signal processing apparatus for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal. Imaging means for converting the subject image into the image signal and storing the image signal; detecting means for detecting a low-luminance part or high-luminance part of the image signal stored by the imaging means; Color level control means for controlling the level of a color signal of a luminance portion or a high luminance portion; limiting a band of a color signal of the image signal; performing gamma correction on the band-limited color signal; Color processing means for processing the color signal thus obtained into the color difference signal; and luminance / color difference correction means for controlling a color component balance of the luminance signal, wherein the color level control means controls the color band. It is provided before being, and controlling the color components balance by the color level control means and the luminance and color difference correction means controlled color signal by.

Preferably, in claims 1 and 2,
A luminance / color difference correction unit that controls a color component balance of a luminance signal with a color signal controlled by the color level control unit;
Aperture correction means for correcting the band of the luminance signal, wherein the luminance / color difference correction means controls the color component balance of the luminance signal before the aperture correction means.

According to a fourth aspect of the present invention, there is provided an imaging signal processing method for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal. In the processing method, a detecting step of detecting a low-luminance portion or a high-luminance portion of the image signal; and a color-level control step of controlling a level of a signal of a color of the low-luminance portion or the high-luminance portion detected by the detecting step. A color processing step of limiting a band of a color signal of the image signal, performing gamma correction on the band-limited color signal, and processing the gamma-corrected color signal into the color difference signal; A luminance / color difference correction step of controlling a color component balance of a signal, wherein the color level control step is performed before gamma correction of the color signal in the color processing step. Characterized in that at the serial color level control color signal controlled by the step executing the luminance and color difference correction step of controlling the color component balance.

According to a fifth aspect of the present invention, there is provided an imaging signal processing method for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal. In the processing method, a detecting step of detecting a low-luminance portion or a high-luminance portion of the image signal; and a color-level control step of controlling a level of a signal of a color of the low-luminance portion or the high-luminance portion detected by the detecting step. A color processing step of limiting a band of a color signal of the image signal, performing gamma correction on the band-limited color signal, and processing the gamma-corrected color signal into the color difference signal; A luminance / color difference correction step of controlling a color component balance of a signal, wherein the color level control step is performed before the color band is limited, and That in a controlled color signals to perform the luminance and color difference correction step of controlling the color component balance wherein.

Preferably, in claims 4 and 5,
A luminance / color difference correction step of controlling a color component balance of a luminance signal with a color signal controlled by the color level control step; and an aperture correction step of correcting a band of the luminance signal. The method is characterized in that it is performed before the aperture correction step.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram schematically showing a signal processing apparatus according to a first embodiment of the present invention. Hereinafter, each block will be described.

Reference numeral 1 denotes a CCD as an image pickup means, which converts a received image into an electric signal, accumulates the electric signal, and outputs the analog signal. A color filter is provided on the surface of the light receiving section of the CCD 1. Color filters include, for example, yellow (Ye), cyan (Cy), and magenta (M
z) and green (G) complementary color filters, and red (R), green (G) and blue (B) pure color filters. Can be used. In the CCD 1 of the signal processing device according to the first embodiment of the present invention, for example, as shown in FIG. 2, the pixels 31, 32, 33 and 34 on the n-th line, and the pixels 39 on the n + 2 In 40, 41, and 42, the colors of the Ye and Cy color filters are assigned in a two-pixel cycle array, and pixels 35, 36, and 37 of the (n + 1) th line are assigned.
And 38, and the colors of the Mz and G color filters are assigned to the (n + 3) th pixels 43, 44, 45, and 46 in a two-pixel cycle array. That is, Ye, C
A complementary color filter having a two-pixel cycle array to which color filters composed of y, G, and Mz colors are assigned is used.

Reference numeral 2 denotes an A / D conversion circuit, which converts an analog signal from the CCD 1 into a digital signal of an arbitrary bit. Usually, this digital signal is output in about 10 bits.

Reference numeral 51 denotes a series of processing blocks of the color processing system, and finally outputs a color difference signal. Further, it is a color processing means for performing processing for limiting the band of the color signal in the digital signal output from the A / D conversion circuit 2. The color processing system 51 includes processing of each of the blocks 3 to 7.

Reference numeral 52 denotes a series of processing blocks of the luminance processing system, which finally output a luminance signal. Brightness processing system 5
2 includes processing of each of blocks 8 to 11.

Next, each block included in the color processing system 51 will be described.

Reference numeral 3 denotes a color interpolation circuit which combines digital signals of the colors of the complementary color filters to generate a color obtained by combining four complementary colors (Ye, Cy, Mz and G) for each pixel. A complementary color signal is output by interpolation.

Reference numeral 4 denotes a matrix circuit, which converts a complementary color signal into a matrix to produce three pure colors (R, G, and B) and outputs RGB signals. The optimum RGB signal is output by appropriately changing the matrix coefficient in consideration of the spectral sensitivity characteristics of the color filter, the color temperature of the subject, and the like.

Reference numeral 5 denotes a color suppression circuit serving as a color level control unit, which removes color noise in a low luminance portion from the RGB signal output from the matrix circuit 4 and also includes a saturated pixel color of the CCD 1 containing a high luminance color. Can be suppressed.
That is, a low-luminance part or a high-luminance part of a luminance signal can be detected and its color level can be controlled, which is called color suppression. Although the details of this circuit will be described later, this circuit includes a luminance level detection circuit 70 as a detecting means as shown in FIG.

Reference numeral 6 denotes a gamma correction circuit which performs gamma correction on an RGB signal by, for example, outputting a 10-bit input signal in 8 bits.

Reference numeral 7 denotes a color difference matrix circuit,
The signal is converted into a color difference signal RY and a color difference signal BY.

Next, each block included in the luminance processing system 52 will be described.

Numeral 8 denotes a color carrier removing circuit, which has an A / D
The digital signal from the conversion circuit 2 is passed through a low-pass filter or the like to remove a color carrier component and output only a luminance signal.

Reference numeral 9 denotes a luminance / color difference correction circuit. If the color temperature of the subject is greatly deviated from the color temperature preset in the color filter of the CCD 1, the balance of the color components in the luminance signal is lost. This is corrected by the color difference signal. For example, if the color temperature of the subject is CCD1
When the color temperature is lower than the preset color temperature of the color filter, the luminance component of the red part of the subject processed and reproduced by the signal processing device becomes large, giving the impression that the color is floating, so this is corrected. I do.

Reference numeral 10 denotes an aperture correction circuit as an aperture correction means, which is a high-frequency signal lost by an optical low-pass filter (not shown) or a low-pass filter of the color carrier removal circuit 8 before the received image reaches the CCD 1. Correct the components.

Numeral 11 denotes a gamma correction circuit, which performs gamma correction on a luminance signal, for example, by outputting a 10-bit input signal in 8 bits. This is a correction circuit for compensating for the inverse gamma characteristic of a TV monitor or the like and projecting a linear image on a screen. It is an important circuit block not only for a TV monitor, but also for printer output and JPEG compression and for high image quality.

Here, reference numeral 12 located between the color processing system 51 and the luminance processing system 52 is a correction matrix circuit.
This is a circuit for generating a color difference signal for luminance and color difference correction used in the luminance and color difference correction circuit 9 of the luminance processing system 52 from the RGB signal output of the color suppression circuit 5 of the color processing system 51.

Next, the color suppression circuit 5 of the signal processing device according to the first embodiment of the present invention will be described with reference to FIG.

The color suppression circuit 5 includes a luminance matrix circuit 6
9, a luminance level detection circuit 70, multipliers 61 to 64, adders 65 to 67, and a subtractor 68.

The luminance matrix circuit 69 is a circuit not included in the color suppression circuit of the conventional signal processing device. In the conventional color suppression circuit, as shown in FIG. 14, a luminance level detection circuit 71 calculates a color gain coefficient k, and outputs a color difference signal RY and a color difference signal BY which are input signals. Multipliers 72 and 73 multiply the color difference coefficient k by the color gain coefficient k to obtain a color difference signal k (RY) and a color difference signal k.
As can be seen from the output of (BY), the signal input to and output from the color suppression circuit was a color difference signal. However, since the signals input to and output from the color suppression circuit 5 according to the first embodiment of the present invention are RGB signals, the luminance matrix circuit 6 converts the RGB signals into a luminance signal Y in a matrix.
9 have been introduced.

As shown in FIG. 4, the luminance level detection circuit 70 according to the first embodiment of the present invention comprises a low-pass filter (LPF) 91, comparators 92 and 93, a low luminance gradient coefficient circuit 94, a high luminance The color suppression circuit 5 includes a gradient coefficient circuit 95, limiters 97 and 98, and a selector 99. The color suppression circuit 5 outputs a color gain coefficient k in accordance with the input luminance signal Y.

The low pass filter (LPF) 91 limits the band of the input luminance signal. The frequency characteristic of the low-pass filter (LPF) 91 is wider than or equal to the frequency band of the color signal to be color-suppressed. This is because, when the band of the color signal to be color-suppressed is narrower, not only the signal of the color to be color-suppressed but also the signals of the surrounding colors are suppressed. When the signal of the color to be color-suppressed is suppressed not only for the designated pixel but also for the periphery thereof, the low-pass filter (LPF) 91 expands the target pixel and performs color suppression of the neighboring pixels. . Therefore, the frequency band of the signal for detecting the luminance portion is not narrower than the frequency band of the color difference signal for performing color suppression, so that it is possible to color-suppress correctly saturated pixels.

The comparator 92 compares the low-luminance portion color noise boundary level (A), which is a reference value, with the level of the luminance signal Y output from the low-pass filter (LPF) 91. As a result of the comparison, when the level of the luminance signal Y is equal to or higher than the low luminance portion color noise boundary level (A), the limiter 97 is controlled to set the color gain coefficient k to 1. On the other hand, when the level of the luminance signal Y is equal to or lower than the low-luminance-portion color noise boundary level (A), the low-luminance-portion slope coefficient circuit 94 supplies the output of the low-pass filter (LPF) 91 with the gradient a of the increasing straight line on the low-luminance-portion side. And output from the limiter 97. If the coefficient of the gradient a is large and the color gain coefficient k exceeds 1 before the level of the luminance signal Y reaches the low luminance portion color noise boundary level (A), the limiter 97 is controlled to increase the color gain coefficient. Fix to 1.

The comparator 93 has a high-luminance portion color suppression boundary level (B), which is a reference value, and a low-pass filter (L).
PF) 91 are compared. As a result of the comparison, when the level of the luminance signal Y is equal to or lower than the high luminance portion color suppression boundary level (B), the selector 99 is selected as the output side of the limiter 97, and the color gain coefficient k is set to 1. On the other hand, when the level of the luminance signal Y is equal to or higher than the high-luminance-part color suppression boundary level (B), the selector 99 is selected as the output side of the limiter 98 and the output of the low-pass filter (LPF) 91 is supplied to the high-luminance-part gradient coefficient circuit. The signal multiplied by the coefficient -b at 95 and the offset value corresponding to k are added, and the coefficient of the slope -b and the adder 100 realize a decreasing straight line on the high luminance portion side. Note that the limiter 98 prevents the output from becoming negative.

Accordingly, the luminance level detection circuit 70 can output the color gain coefficient k from the level of the luminance signal Y, and the relationship is as shown in FIG.

The luminance level detection circuit 70 calculates the color gain coefficient k along a locus having a linear gradient a when the level of the luminance signal increases up to the low luminance portion color noise boundary level (A). The noise of the low brightness part color is removed. Further, the luminance level detection circuit 70 sets the color gain coefficient k to a constant 1 when the luminance signal level rises from the low luminance part color noise boundary level (A), but calculates the high luminance part color suppression boundary level. (B) At the level of the luminance signal described above, the color gain coefficient k is calculated by decreasing the level of the luminance signal along a locus having a linear slope of −b, and the color of the high luminance portion is suppressed.

Next, the operation of the color suppression circuit 5 will be described.
This will be described with reference to FIG.

As described above, the signal input to the color suppression circuit 5 is an RGB signal, and the luminance matrix circuit 69 converts the RGB signal into a luminance signal Y by matrix conversion derived by the following equation, and performs color suppression. be able to.

[0047]

(Equation 1) Equation (2) is derived from equation (1).

[0048]

(Equation 2) Here, the following equation (3) is obtained in consideration of the color gain coefficient k.

[0049]

(Equation 3) Expanding equation (3), R = Y + k (RY) = kR + (Y-kY) (4) G = Y + k (G-Y) = kG + (Y-kY) (5) B = Y + k ( (BY) = kB + (Y-kY) (6)

Therefore, in the color suppression circuit 5, as shown in FIG. 3, first, in the above-mentioned luminance level detection circuit 70, a coefficient of 0 to 1 which is a coefficient for color-suppressing the color difference signal from the luminance signal Y is used. A color gain coefficient k is calculated. The R signal, G signal, and B signal of the RGB signals, which are the input signals, are respectively processed by multipliers 61, 62, and 63.
It is multiplied by the calculated color gain coefficient k. on the other hand,
In the luminance matrix circuit 69, the input signal RG
The luminance signal Y obtained by matrix conversion from the R signal, the G signal, and the B signal of the B signal is multiplied by a color gain coefficient k by a multiplier 64, and is subtracted from the original luminance signal Y by a subtractor 68 (Y−kY). Get the output of Therefore, the R signal, G signal, and B signal multiplied by k as described above include (Y-k
The output of Y) is added by adders 65, 66 and 67 to obtain color-suppressed RGB signals. That is, the above four equations,
The rightmost sides of Equations 5 and 6 are output. In these color-suppressed RGB signals, as the color gain coefficient k approaches 0, the level of the original RGB signal decreases to suppress the color. Conversely, when the color gain coefficient k is 1, the original RGB signal RGB
Only signal. Therefore, the color suppression circuit 5 can remove the color noise of the low luminance portion of the input RGB signal and suppress the color of the saturated pixel of the CCD 1 including the high luminance color.

Next, the operation of the signal processing of the signal processing device according to the first embodiment of the present invention will be described with reference to FIG.

The received image of the subject image is converted into an electric signal by the CCD 1 and converted from an analog signal to a digital signal by the A / D conversion circuit 2. The converted digital signal is processed separately in a color processing system 51 and a luminance signal system 52.

In the color processing system 51, the digital signal output from the A / D conversion circuit 2 is output to the color interpolation circuit 3 by the CCD 1.
Yellow (Ye), cyan (Cy),
It is output as four complementary color signals consisting of magenta (Mz) and green (G). The complementary color signal is output from the matrix circuit 4
And red (R), green (G) and blue (B)
, And output as RGB signals. Next, in the color suppression circuit 5, a low-luminance part or a high-luminance part is detected from the level of the luminance signal of the color carrier elimination circuit 8 of the luminance processing system 52, and the RGB signal removes color noise in the low-luminance part. At the same time, the color of the pixel including the saturated color of the CCD 1 which is saturated is suppressed. Then, in the gamma correction circuit 6, the image signal is matched with a video signal to be displayed on a TV monitor or the like, and converted into a color difference signal by a color difference matrix circuit 7 and output.

The band of the color signal is limited by a series of processes of the color processing system 51 such as the color interpolation circuit 3. That is,
The color signal in the digital signal output from the A / D conversion circuit 2 is subjected to a process of limiting the band by the color processing system 51, and is converted into a color difference signal.

On the other hand, in the luminance processing system 52, the digital signal output from the A / D conversion circuit 2 is subjected to a color carrier removal circuit 8 to remove the color carrier component, and becomes a substantially unprocessed luminance signal. Next, in the luminance signal, the balance of the color components in the luminance signal is corrected by the luminance / color difference correction circuit 9 using the luminance / color difference correction color difference signal. The color difference signal for correcting the luminance and color difference is a color difference signal generated by matrix conversion of the correction matrix circuit 12 from the RGB signal output processed by the color suppression circuit 5. Next, the aperture correction circuit 10 raises the characteristics of the luminance signal in the high frequency region.
Further, the gamma correction circuit 11 performs gamma correction similarly to the color processing system 51, and outputs a final luminance signal.

As described above, according to the first embodiment of the present invention, before the aperture correction and the gamma correction of the luminance processing system 52, the color difference signal obtained by matrix conversion from the RGB signal processed by the color suppression circuit 5 is used. Is used to perform the luminance / color difference correction processing, so that there is no need to provide a delay circuit for adjusting the output timing of the color processing system 51 and the luminance processing system 52.

Therefore, even when the color temperature of the subject is largely deviated from the color temperature preset in the color filter of the CCD 1, the balance of the color components in the luminance signal is not lost, and the aperture of the luminance processing system 52 is maintained. Correction and gamma correction can be performed.

Therefore, when a subject image is reproduced on a TV monitor or the like, remarkable image quality is not deteriorated, and a high-quality video signal can be reproduced.

(Embodiment 2) FIG. 6 is a block diagram schematically showing a signal processing apparatus according to a second embodiment of the present invention.

In the signal processing apparatus according to the second embodiment of the present invention, the CCD 1, the A / D conversion circuit 2, the color interpolation circuit 3, the matrix circuit 4, the gamma correction circuit 6, the color difference matrix circuit 7, the color carrier removal The blocks of the circuit 8, the luminance / color difference correction circuit 9, the aperture correction circuit 10, the gamma correction circuit 11, and the correction color difference matrix circuit 12 are the same as those of the signal processing device according to the first embodiment. Unlike the above-described first embodiment of the present invention, the color suppression circuit 13 detects a low luminance portion or a high luminance portion of a luminance signal and controls the level of a complementary color output from the color interpolation circuit 3. The feature is that it can be done. That is,
In the signal processing device according to the first embodiment of the present invention, the color suppression circuit 5 in the color processing system 51 processes the RGB signals from the matrix circuit 4 and outputs the processed RGB signals to the gamma correction circuit 6. On the other hand, in the signal processing device according to the second embodiment of the present invention, the color suppression circuit 13 in the color processing system 51 processes the complementary color signal from the color interpolation circuit 3 and
The processing procedure is different from that of the first embodiment, and the rest is the same as the signal processing according to the first embodiment of the present invention. Therefore, here, the color suppression circuit 13 will be particularly described with reference to FIG.

The color suppression circuit 13 includes a luminance matrix circuit 91, a luminance level detection circuit 70, and multipliers 81 to 8.
5, adders 86 to 89, and a subtractor 90.

The luminance matrix circuit 91 includes the color suppression circuit 1
The signal input / output in 3 is a complementary color signal, which is introduced to convert the complementary color signal into a luminance signal Y in a matrix.

The luminance level detection circuit 70 is the same circuit as the first embodiment of the present invention described above.

Next, the operation of the color suppression circuit 13 will be described with reference to FIG.

As described above, the signal input to the color suppression circuit 13 is a complementary color signal. In the luminance matrix circuit 91, the complementary color signal is converted into a luminance signal Y by matrix conversion derived by the following equation, and color suppression is performed. be able to.

[0066]

(Equation 4) Equation (8) is derived from equation (7) and equation (2) described above.

[0067]

(Equation 5) Here, the following equation (9) is obtained in consideration of the color gain coefficient k.

[0068]

(Equation 6) Expanding equation (9), for example, for Cy, Cy = m11 [Y + k (RY)] + m12 [Y + k
(G−Y)] + m13 [Y + k (B−Y)] = (m11
+ M12 + m13) Y- (m11 + m12 + m13) k
Y + k (m11R + m12G + m13B) = (m11 +
(m12 + m13) (Y-kY) + kCy Here, (m11 + m12 + m13) is 1 because it is the sum of the component ratios. Therefore, Cy = (Y−kY) + kCy (10). Similarly, for Ye, G, Mz, Ye = (Y−kY) + kYe (11) G = (Y−kY) + kG (12) Mz = (Y−kY) + kMz (13)

Therefore, in the color suppression circuit 13, FIG.
As shown in (1), as in the first embodiment, first, in the luminance level detection circuit 70, a color gain coefficient k from 0 to 1, which is a coefficient for suppressing the color difference signal from the luminance signal Y, is calculated. Is done. Also, Cy of the complementary color signal which is the input signal
Each of the signal, the Ye signal, the Mz signal, and the G signal
Multipliers 81 to 84 multiply the calculated color gain coefficient k. On the other hand, in the luminance matrix circuit 91, the Cy signal, the Ye signal, the M
The luminance signal Y converted from the z signal and the G signal is multiplied by a color gain coefficient k in a multiplier 85, and is subtracted from the original luminance signal Y in a subtractor 90 to obtain an output of (Y−kY). Therefore, the Cy signal multiplied by k as described above, Ye
The output of (Y−kY) is added to the signal, the Mz signal, and the G signal by adders 86 to 89 to obtain a color-suppressed complementary color signal. That is, the right sides of the above-described equations (10) to (13) are output. When the color gain coefficient k approaches 0, the level of the original complementary color signal decreases and the color is suppressed. On the contrary, when the color gain coefficient k is 1, Only the complementary color signal of Therefore, the color suppression circuit 1
No. 3 can remove the color noise of the low-luminance portion of the input complementary color signal and suppress the color of the saturated pixel of the CCD 1 including the high-luminance color.

Next, the operation of the signal processing of the signal processing apparatus according to the second embodiment of the present invention will be described with reference to FIG. 6, but here, in particular, the differences from the first embodiment will be described. I do.

In the color processing system 51, the color interpolation circuit 3 outputs a complementary color signal for each pixel of the CCD 1. In the color suppression circuit 13 according to the second embodiment of the present invention, the complementary color signal is color-suppressed, and the color-suppressed complementary color signal is converted into a pure-color RGB signal by the matrix circuit 4. Is processed in the same manner as in the embodiment, and a color difference signal is output.

The luminance processing system 52 also employs the first method of the present invention.
The luminance signal is output after being processed in the same manner as in the first embodiment. However, since the output of the color suppression circuit 13 in the second embodiment of the present invention is a complementary color signal, the RGB signal converted in the matrix circuit 4 The luminance and chrominance are corrected using the chrominance signals that have been subjected to matrix conversion by the correction matrix circuit 12.

As described above, in the second embodiment of the present invention, in the color processing system 51, the color suppression circuit 13 processes the complementary color signal from the color interpolation circuit 3 and outputs the processed signal to the matrix circuit 4. Therefore, it is not necessary to expand the area than the area in which color suppression is performed in the first embodiment of the present invention. That is,
Since the color suppression processing is performed at an early stage of the color processing system, the color noise of the low-brightness part is removed and the color of the saturated CCD pixel is suppressed without unnecessarily expanding the color suppression area. be able to.

Further, in the second embodiment of the present invention, as in the first embodiment of the present invention, before the aperture correction and the gamma correction of the luminance processing system 52, the color suppression circuit 13 performs Since the luminance and chrominance correction processing is performed using the matrix-converted chrominance signals from the processed correction signals, there is no need to provide a delay circuit for adjusting the output timing of the color processing system 51 and the luminance processing system 52.

Therefore, even when the color temperature of the subject is largely deviated from the color temperature preset in the color filter of the CCD 1, the balance of the color components in the luminance signal is not lost, and the aperture of the luminance processing system 52 is maintained. Correction and gamma correction can be performed.

Therefore, when a subject image is reproduced on a TV monitor or the like, a remarkable deterioration in image quality does not occur, and a high-quality image signal can be reproduced.

(Embodiment 3) FIG. 8 is a block diagram schematically showing a signal processing apparatus according to a third embodiment of the present invention.

In the signal processing apparatus according to the third embodiment of the present invention, the CCD 1, the A / D conversion circuit 2, the color interpolation circuit 3, the matrix circuit 4, the gamma correction circuit 6, the color difference matrix circuit 7, the color carrier removal The blocks of the circuit 8, the luminance / color difference correction circuit 9, the aperture correction circuit 10, the gamma correction circuit 11, and the correction color difference matrix circuit 12 are the same as those of the signal processing device according to the first embodiment. Unlike the above-described embodiment of the present invention, the color suppression circuit 21 detects a low luminance portion or a high luminance portion of a luminance signal and controls the color level of the digital signal output from the A / D conversion circuit 2. The feature is that it can be done. Therefore, here, the color suppression circuit 21 will be described in detail with reference to FIG.

As shown in FIG. 9, the color suppression circuit 21 includes a CCD output saturation detection circuit 121 as a detection means, a delay circuit 122, a luminance signal generation circuit 123, and a multiplier 12.
4 and 125, a subtractor 126, and an adder 127, and is a circuit that removes the color noise of the low-luminance part and suppresses the color of the saturated CCD1 pixel including the high-luminance color. . The color suppression circuit 21 processes a digital signal output from the A / D conversion circuit as an input signal, and this digital signal includes color information in a time-series manner.

Since the input signal is a digital signal output from the A / D conversion circuit, the color suppression circuit 21
The four multipliers 81 to 84 of the color suppression circuit 13 of the second embodiment as shown in FIG. 7 are not required, and one multiplier 124 having the same role is sufficient.

The CCD output saturation detection circuit 121 is the same as the luminance level detection circuit 70 according to the first embodiment of the present invention.
And outputs a color suppression coefficient k1 according to the level of the input signal. That is, the CCD output saturation detection circuit 121 calculates and outputs the color suppression coefficient k1 in accordance with the color level of the designated pixel from among the pixels of the CCD 1 of the digital signal output from the A / D conversion circuit 2.

In the CCD output saturation detection circuit 121,
As in the above-described relationship between the level (horizontal axis) of the luminance signal Y and the color gain coefficient k (vertical axis) shown in FIG. 5, on the low luminance part side, the color suppression coefficient k1 is increased in accordance with the rise in the level of the input digital signal. Becomes larger, and the color suppression coefficient k1 becomes smaller on the high-luminance portion side in accordance with an increase in the level of the input digital signal.
Therefore, the same circuit can remove the noise of the color on the low-luminance portion side and suppress the color of the pixel including the saturated high-luminance color of the CCD 1 with the same circuit.

The delay circuit 122 is a circuit for delaying the digital signal output from the A / D conversion circuit 2 in accordance with the output timing of the CCD output saturation detection circuit 121. Usually, flip-flops and the like are used.

Next, the luminance signal generating circuit 123
This is a circuit for generating a luminance signal Y from a pixel designated from among one pixel and surrounding pixels. That is, when the luminance signal Y is generated from the pixels of the CCD 1 whose saturation is detected by the CCD output saturation detection circuit 121 and the surrounding pixels, color suppression is required. For example, in a CCD having a color filter array as shown in FIG.
When the pixel 41 having the color filter of is saturated, the luminance signals affected by the saturation of the pixel 41 are pixels 36, 3
The luminance signal Y1 composed of 7, 40 and 41 and the pixel 3
A luminance signal Y2 composed of pixels 7, 38, 41 and 42 and a luminance signal Y3 composed of pixels 40, 41, 44 and 45
And a luminance signal Y4 composed of pixels 41, 42, 45 and 46. These pixels 36, 37, 38, 40,
It is necessary to multiply 41, 42, 44, 45 and 46 by the same color suppression coefficient k1 for color suppression.

As shown in FIG. 10, the luminance signal generation circuit 123 includes one horizontal line data delay circuit 131, a multiplier 1
32 and 133, hold adders 134 and 13
5, an adder 136, and a selector 137.

One horizontal line data delay circuit 131
Among the digital signals output from the / D conversion circuit 2, the CCD
The pixel data for one horizontal line can be delayed, and the circuit is constituted by a circuit for storing and reading out pixel data for one horizontal line of the CCD 1 in an SRAM or the like.

Since the digital signal output from the A / D conversion circuit 2 includes color information in a time-series manner, the selector 137 provides color information for multiplication by the multipliers 132 and 133, that is, Ye of a complementary color. , Cy, G, and Mz, a matrix coefficient for conversion into RGB is appropriately selected so as to be optimal, and the following equation (1) is used.
This is a circuit for converting a digital signal output from the A / D conversion circuit 2 into a luminance signal Y using the matrix coefficient of 4).

The multipliers 132 and 133 are provided in FIG.
As shown in the figure, the data of the pixels of the CCD 1 adjacent in the horizontal direction are multiplied, and the hold adders 134 and 1
35 weights these data, and an adder 136
Add the signal from the hold adder circuit 134 and the signal from the hold adder circuit 135.

Therefore, the luminance signal generation circuit 123 converts the digital signal from the A / D conversion circuit containing the color information in a time series into an RGB signal.
An operation of converting and outputting the luminance signal Y is performed as shown in 4).

[0090]

(Equation 7) Here, the operation of the color suppression circuit 21 will be described with reference to FIG.

The digital signal output at the same timing from the delay circuit 122 is multiplied by the multiplier 124 by the calculated color suppression coefficient k1 in the CCD output saturation detection circuit 121. Further, the luminance signal Y generated in the luminance signal circuit is multiplied by the color suppression coefficient k1 in the multiplier 125 and subtracted from the original luminance signal Y in the subtractor 126, so that (Y−k1Y) is output. You. Accordingly, the operation result is obtained in the adder 127, and a digital signal whose color has been suppressed in time series is output.

The color-suppressed digital signal has a color suppression coefficient k
As 1 approaches 0, the level of the original digital signal decreases and the color is suppressed. Conversely, when the color suppression coefficient k1 is 1, only the original digital signal is obtained. That is, it is possible to remove the color noise of the low-luminance portion of the digital signal and to suppress the color of the saturated pixel of the CCD 1 including the high-luminance color.

Next, the operation of the signal processing of the signal processing apparatus according to the third embodiment of the present invention will be described with reference to FIG. 8, but here, in particular, the points different from the first embodiment will be described. I do.

In the color processing system 51, first, the digital signal output from the A / D conversion circuit 2 is color-suppressed by the color suppression circuit 21. In the color interpolation circuit 3, each pixel of the CCD 1 is yellow (Ye). , Cyan (Cy), magenta (Mz) and green (G). The complementary color signal is converted by the matrix circuit 4 into a pure color including red (R), green (G), and blue (B) and output as an RGB signal. Next, the processing is performed by the gamma correction circuit 6 and the color difference matrix circuit 7 to be output as a color difference signal RY and a color difference signal BY.

On the other hand, in the luminance processing system 52, the first
RGB from the matrix circuit 4 as in the embodiment
A luminance / color difference correction signal is generated from the signal by the correction matrix circuit 12, the luminance / color difference correction is performed on the luminance signal after removing the color carrier, and then the aperture correction and the gamma correction are performed to output the luminance signal. Further, since the luminance signal generation circuit 123 is included in the above-described color suppression circuit 21, the luminance signal output from the color carrier removal circuit 8 is not input to the color suppression circuit 21.

As described above, in the third embodiment of the present invention, the color is suppressed by the digital signal output from the A / D conversion circuit 2. Performing the color suppression processing at the initial stage of the color processing system allows the color suppression processing to be performed before being affected by the band limitation due to the series of processing of the color processing system. When the subject image is reproduced on a TV monitor or the like without spreading around, correct color processing for obtaining a high-quality image can be performed.

(Embodiment 4) In a signal processing apparatus according to a fourth embodiment of the present invention, a color suppression circuit 21 shown in FIG. 8 described in the third embodiment of the present invention is replaced with a color A case where a correction circuit is used will be described. That is, instead of multiplying the color by the color suppression coefficient k1 and detecting the saturation of the pixel of the CCD, the saturated pixel is corrected by interpolating from the pixels around the saturated pixel.

Therefore, the processing of the other blocks of the color correction circuit is the same as that of the third embodiment, and the color correction circuit will be described below.

In the interpolation of the color correction circuit, there are cases where one-dimensional and two-dimensional linear interpolation, or interpolation or the like is performed based on the characteristics of a low-pass filter by expanding a pixel area for interpolation.

First, the case where one-dimensional linear interpolation is performed will be described.

FIG. 11 shows a color correction circuit for performing color correction by one-dimensional linear interpolation, and includes a CCD output saturation detection circuit 141, an interpolation circuit 142, and a selector 143.

The CCD output saturation detection circuit 141 has an A / D
It outputs 1 when the output of the digital signal output from the conversion circuit 2 is saturated, and outputs 0 when it is not saturated. The interpolation circuit 142 is a circuit for compensating for a saturated pixel from a pixel of the same color around a saturated CCD pixel when there is a saturated pixel in the CCD, and shows a case where one-dimensional linear interpolation is used. I have.

The selector 143 is switched by the output of the CCD output saturation detecting circuit 141. Usually A / D
Although the digital signal output from the conversion circuit 2 is selected so as to be output as it is, if there is a saturated pixel in the CCD, the selector is switched, and the interpolated digital signal of the saturated pixel is output from the interpolation circuit 142. You.

Here, the interpolation circuit 142 has delay circuits 144 and 147 for delay amounts corresponding to the intervals between pixels of the same color of the CCD 1, an adder 145, and a 1/2 circuit 146. Further, the 回路 circuit 146 specifically functions to shift data by one bit toward the low side band (LSB). Therefore, when the saturation of the CCD pixel is detected, the signals of the pixels around the saturated pixel can be used.

Next, a case will be described in which the area around the pixel for interpolation is expanded and low-pass filter characteristic interpolation is performed.

When the low pass filter characteristic is interpolated by expanding the area surrounding the pixel for interpolation, the interpolation circuit 142 for color correction by one-dimensional linear interpolation is different from the interpolation circuit 158 shown in FIG. And a delay circuit 154,
155, 156, and 157 are used and are constituted by coefficient circuits 151 and 152 and adders 153, 159 and 160. Here, the interpolation operation of the interpolation circuit 158 is such that the input of the digital signal output from the A / D conversion circuit 2 and the output of the delay circuit 157 are added by an adder 159, and the outputs of the delay circuit 154 and the delay circuit 156 are added. The addition is performed at 160, multiplied by a predetermined coefficient at coefficient circuits 151 and 152, and added at an adder 153. That is, the interpolation circuit 158 forms a digital filter whose filter characteristics are determined by the coefficients of the coefficient circuits 151 and 152. The configuration other than the interpolation circuit 158 is the same as that in the case where the one-dimensional linear interpolation shown in FIG. 11 is used.

As described above, according to the fourth embodiment of the present invention, when there is a saturated pixel in the CCD, instead of suppressing the color, the saturated pixels from the pixels of the same color around the saturated CCD pixel are replaced. , A circuit having a smaller gate scale than the color suppression circuit can be obtained.

Further, in the case of a subject image such as a human face, a high-brightness portion which reflects light from the head and nose can reproduce a more natural image when processed by an interpolation circuit than color suppression. Can be.

[0109]

As described above, according to the present invention, without providing a delay circuit for adjusting the output timing of the color processing system and the luminance processing system, the color processing can be performed before the aperture correction and the gamma correction of the luminance processing system. The luminance and color difference can be corrected using the RGB signal, the correction signal, and the color difference signal obtained by converting the digital signal into a matrix.

Therefore, even when the color temperature of the subject is largely deviated from the color temperature preset in the color filter of the CCD, the balance of the color components in the luminance signal is not lost, and the aperture correction of the luminance processing system is performed. And gamma correction can be processed.

Therefore, when a subject image is reproduced on a TV monitor or the like, remarkable image quality is not deteriorated, and a high-quality video signal can be reproduced.

It should be noted that instead of the color suppression processing, saturated C
The same effect can be obtained by performing a process of supplementing a saturated pixel from pixels of the same color around a pixel of the CD. Further, in the case of a subject image such as a human face, a high-brightness portion that reflects light from the head or nose can reproduce a more natural image by processing with an interpolation circuit than with color suppression.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a signal processing device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a complementary color filter of a CCD according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining a color suppression circuit according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a luminance level detection circuit according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining a relationship of outputting a color gain coefficient k from a level of a luminance signal Y of the luminance level detection circuit according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating a schematic configuration of a signal processing device according to a second embodiment of the present invention.

FIG. 7 is a diagram for describing a color suppression circuit according to a second embodiment of the present invention.

FIG. 8 is a block diagram illustrating a schematic configuration of a signal processing device according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a color suppression circuit according to a third embodiment of the present invention.

FIG. 10 is a diagram for describing a luminance signal generation circuit according to a third embodiment of the present invention.

FIG. 11 is a diagram illustrating a case where one-dimensional linear interpolation is used for a color correction circuit according to a fourth embodiment of the present invention.

FIG. 12 is a diagram for explaining a case in which a color correction circuit according to a fourth embodiment of the present invention performs interpolation of low-pass filter characteristics by expanding a surrounding area of an interpolation pixel.

FIG. 13 is a block diagram illustrating a schematic configuration of a conventional signal processing device.

FIG. 14 is a diagram for explaining a conventional color suppression circuit.

[Explanation of symbols]

Reference Signs List 1 CCD 2 A / D conversion circuit 3 Color interpolation circuit 4 Matrix circuit 5, 13, 20, 21 Color suppression circuit 6, 11 Gamma correction circuit 7 Color difference matrix circuit 8 Color carrier removal circuit 9 Luminance / color difference correction circuit 10 Aperture correction circuit 12 Correction matrix circuit 69 Luminance matrix circuit 70, 71 Luminance level detection circuit 91 Low pass filter 94 Low luminance section gradient coefficient circuit 95 High luminance section gradient coefficient circuit 97, 98 Limiter 99, 137 Selector 121 CCD output saturation detection circuit 122 Delay Circuit 123 Luminance signal generation circuit 131 1 Horizontal line delay circuit 141 CCD output saturation detection circuit 144, 147, 154, 155, 156, 157
Delay circuit

Claims (6)

[Claims] 1. A signal processing device for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal, wherein: an imaging unit for converting the subject image into the image signal and storing the image signal; Detecting means for detecting a low-luminance part or high-luminance part of the image signal accumulated by the imaging means; and color-level control means for controlling the level of the color signal of the low-luminance part or high-luminance part detected by the detecting means A color processing unit that limits a band of a color signal of the image signal, performs gamma correction on the band-limited color signal, and processes the gamma-corrected color signal into a color difference signal; Brightness and color difference correction means for controlling the color component balance of the signal, wherein the color level control means is provided before gamma correction of the color signal in the processing path of the color processing means, A signal processing apparatus, wherein a color component balance is controlled by said luminance / color difference correction means with a color signal controlled by control means. 2. A signal processing device for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal, wherein: an imaging unit for converting the subject image into the image signal and storing the image signal; Detecting means for detecting a low-luminance part or high-luminance part of the image signal accumulated by the imaging means; and color-level control means for controlling the level of the color signal of the low-luminance part or high-luminance part detected by the detecting means A color processing unit configured to limit a band of a color signal of the image signal, perform gamma correction on the band-limited color signal, and process the gamma-corrected color signal into the color difference signal; A luminance / color difference correction unit for controlling a color component balance of a luminance signal, wherein the color level control unit is provided before the band of the color is restricted, and a color signal controlled by the color level control unit is provided. A signal processing apparatus for controlling a color component balance by the luminance / color difference correction means. 3. A luminance / color difference correction unit for controlling a color component balance of a luminance signal with a color signal controlled by the color level control unit; and an aperture correction unit for correcting a band of the luminance signal. The signal processing device according to claim 1, wherein the luminance / color difference correction unit controls a color component balance of the luminance signal before the aperture correction unit. 4. An imaging signal processing method for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal, comprising: a detecting step of detecting a low luminance portion or a high luminance portion of the image signal. A color level control step of controlling a level of a color signal of a low-luminance part or a high-luminance part detected by the detection step; and limiting a band of a color signal of the image signal, and limiting the band of the color. A color processing step of: gamma-correcting a signal of the color signal; and processing the gamma-corrected signal of the color into the color-difference signal; and a luminance-color difference correction step of controlling a color component balance of the luminance signal. Performing the step before gamma correction of the color signal in the color processing step, and performing color component balance with the color signal controlled by the color level control step. Imaging signal processing method characterized by performing the Gosuru the luminance and color difference correction step. 5. An imaging signal processing method for converting a subject image into an image signal and processing the image signal into a luminance signal and a color difference signal, comprising: a detecting step of detecting a low luminance portion or a high luminance portion of the image signal. A color level control step of controlling a level of a color signal of a low-luminance part or a high-luminance part detected by the detection step; and limiting a band of a color signal of the image signal, and limiting the band of the color. A color processing step of: gamma-correcting a signal of the color signal; and processing the gamma-corrected signal of the color into the color-difference signal; and a luminance-color difference correction step of controlling a color component balance of the luminance signal. Performing the step before the color band is limited, and controlling the color component balance by the color signal controlled by the color level control step. Imaging signal processing method characterized by performing the flop. 6. A luminance / color difference correction step of controlling a color component balance of a luminance signal with a color signal controlled by the color level control step, and an aperture correction step of correcting a band of the luminance signal, 6. The luminance and color difference correction step is performed before the aperture correction step.
3. The imaging signal processing method according to 1.