JPH08214320A - Chrominance signal converter in single plate type color camera - Google Patents

Abstract

PURPOSE: To obtain a desired chrominance signal by reducing moire from a color component signal from a color filter with prescribed color arrangement without depending on color temperature. CONSTITUTION: A color image pickup element 10 outputs the color component signals Wb, Gr on, for example. (n) scanning lines from a filter with prescribed color arrangement, and outputs the color component signals Wb, Gb on (n+1) scanning lines. A concurrency part 20 performs the concurrency of the color component signals Wb, Gr, Gb and Wr. A correction part 30 calculates an addition signal (Wb+Gb) from the color component signals on the (n) lines out of concurred color component signals by a first horizontal addition circuit 32, and an addition signal (Wr+Gb) from the (n+1) lines by a second horizontal addition circuit 34, and they are supplied to a coefficient calculation circuit 38 as a ratio Hn=(Wr+Gb)/(Wb+Gr) by a comparison circuit 36. The coefficient calculation circuit 38 calculates and corrects coefficients Kn=(0.5+-0.5Hn), k(n+1)=(0.5+0.5/Hn) to correct the color component signals on the (n) and (n+1) lines, respectively. In this way, the color component signal supplied to a matrix arithmetic circuit 42 is corrected as a picture element signal suitable for density gradient and averaged on respective line, and the influence of moire is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal conversion device in a single-plate color camera which obtains a color image signal representing a subject image with a single color image pickup device, and more particularly, for example, a complementary color filter having a predetermined arrangement. The present invention relates to a color signal conversion device in a single-panel color camera that obtains desired color signals such as R, G, and B signals from a plurality of color component signals that have been transmitted.

[0002]

2. Description of the Related Art CCDs (Charged
An image sensor such as a Coupled Device) is equipped with a filter of a predetermined color array, detects the color component signals representing each pixel of the subject image that has passed through this color filter, and converts these to the desired color signal. To obtain an image signal representing the subject image. For example, as shown in FIG. 2, a field accumulation line sequential type single-plate CCD camera using a color filter in which four types of complementary color filters of magenta Mg, yellow Ye, green G, and cyan Cy are arranged in each pixel is shown. Are known.

In this CCD camera, signals from pixels of vertically adjacent rows in the CCD are added, mixed, and output. For example, in the n horizontal scanning lines, the color component signal Wb in which magenta Mg and cyan Cy are mixed and the color component signal Gr in which green G and yellow Ye are mixed are alternately output. In the (n + 1) horizontal scanning line, a color component signal Wr mixed with magenta Mg and yellow Ye and a color component signal Gb mixed with green G and cyan Cy are alternately output. As a result, in the n horizontal scanning lines, the color component signal is added to the DC component.
Wb, Gr added (Wb + Gr) = (Mg + Cy) + (G + Ye) = (2R + 3G + 2
(B) includes the luminance signal component, and the fundamental wave component is the difference signal of the color component signals Wb and Gr (Wb-Gr) = (Mg + Cy)-(G + Ye) = (2R-
The color difference signal component as G) is included. Similarly, (n +
1) In the horizontal scanning line, (Wr + Gb) = (Mg + Ye) +
The luminance signal component of (G + Cy) = 2R + 3G + 2B is included, and the color difference signal component of (Wr-Gb) = (Mg + Ye)-(G + Cy) = (2B-G) is included in the fundamental wave component. It is included.

Therefore, for example, a low-pass filter (2R + 3G + 2B) is passed through each low-pass filter for each scanning line.
Is detected as a luminance signal, and each color difference component (2R-G), (2B-G) is detected by detecting it through a bandpass filter centered on the fundamental frequency in each scanning line.
-G) is separated to detect the color difference signal. Further, the color difference signals are synchronized with each other, whereby a color difference line-sequential composite color signal including a luminance signal and a color difference signal can be obtained.

However, in this method, two types of color component signals Wb, Gr or Wr, G mixed for each scanning line are used.
Since the color difference signal (2R-G) or (2B-G) is obtained only from b, the degree of freedom of color reproducibility that strongly depends on the spectral characteristics of the color filter was small.

Therefore, for example, the pixel mixture CC described in page 49 to page 54 of Technical Report Vol. 13, No. 11 of the Television Society of Japan.
For simultaneous RGB processing in a D camera (Nishimura et al., Announced in February 1989), an apparatus has been proposed that obtains a color signal with improved color reproducibility from the color component signals from the complementary color filter similar to the above.

In this device, a color component signal read from the CCD is delayed by a horizontal delay line for one horizontal period, and
The color component signals Wb, Wr, Gr, Gb adjacent to each other in the horizontal direction and the vertical direction are detected from the direct signal, and these are synchronized by a multiplexer or the like.

Four types of color component signals Wr, Gb, G which are synchronized with each other
r, Wb are generated as color signals R, G, B by calculating as in the following equation (1) in a matrix calculating circuit. As a result, a color signal can be reproduced using four types of color component signals from the two lines of the n horizontal line and the (n + 1) horizontal line, and the degree of freedom can be increased.

[0009]

[Equation 1]

In this case, the arbitrary constants α, β and γ are "0".
A value between 1 and "1" may be used, but in the above-mentioned document, the following condition was set in consideration of the moire suppression relationship.

[0011]

[Equation 2]

[0012]

(Equation 3)

In particular, α and β have been set so as to satisfy the expression (2) for white light having an appropriate color temperature.

As described above, in the above-mentioned document, the color component signals of the pixels adjacent in the horizontal and vertical directions are synchronized from the output signal of the CCD sensor having the complementary color filter, and the above equations (1) to (3) are used. As shown in, the matrix calculation coefficients are optimized and set, and the color signals R, G, B are suppressed while suppressing moire.
Therefore, the degree of freedom of color reproducibility was increased.

[0015]

However, in the above-mentioned conventional technique, color moire occurs unless the coefficients α and β are optimized as shown in equation (2) each time the color temperature of the light source changes. Therefore, it is necessary to prepare and switch the coefficient for each color temperature. In this case, for example, the color temperature must be measured when the illumination condition from the sunlight to the fluorescent lamp changes, and the coefficient must be set based on the color temperature. However, since it is difficult to accurately measure the color temperature, it is difficult to optimize the coefficient, which causes color moire. Further, there has been a problem that unless a coefficient for each color temperature is created for each type of color component signal at that time, it is not possible to follow stepwise processing for each color temperature and abrupt change of illumination conditions.

The present invention solves the above problems and prevents the occurrence of moire with respect to different color temperatures, and can cope with various color component signals only with predetermined coefficients. An object of the present invention is to provide a stable color signal conversion device in a single-plate color camera.

[0017]

In order to solve the above-mentioned problems, a color signal conversion device for a single-plate color camera according to the present invention sequentially outputs from a single image pickup device equipped with a filter having a predetermined color arrangement. In a color signal conversion device in a single-plate color camera that converts a plurality of color component signals into a desired color signal, the color component signals sequentially output from the image sensor are output for each of a plurality of pixels that are adjacent in the horizontal and vertical directions. A correction coefficient is calculated based on a plurality of color component signals which are detected and synchronized, and a plurality of color component signals which are synchronized by the synchronization means, and the color component signals from the synchronization means are respectively calculated by this correction coefficient. The correction unit includes a correction unit that corrects and a matrix calculation unit that performs a predetermined calculation on the corrected color component signal from the correction unit to obtain a desired color signal.
According to the ratio of the color component signals in the vertical direction to the total pixel value of the synchronized multiple color component signals, a correction coefficient is calculated so that each color component signal becomes an averaged value, and this correction is performed. It is characterized in that each color component signal is corrected by a coefficient.

In this case, the correction means includes a horizontal addition means for adding the color component signals in the horizontal direction among the plurality of synchronized color component signals, and a vertical addition means for taking the ratio in the vertical direction from the addition result of the horizontal addition means. It is preferable to have a comparing means and a coefficient calculating means for calculating a correction coefficient for each horizontal scanning line from the comparison result of the comparing means.

The color filters are magenta Mg and cyan.
The image sensor includes four types of complementary color filters of Cy, green G, and yellow Ye, and the image pickup device mixes green G and yellow Ye with the first color component signal Wb in which magenta Mg and cyan Cy are mixed in n scanning lines. The second color component signal Gr is output alternately, and the third color component signal Wr in which magenta Mg and yellow Ye are mixed and the fourth in which green G and cyan Cy are mixed in the (n + 1) scanning line. Alternately output the color component signal Gb of the image sensor, and the synchronizing means synchronizes the adjacent color component signals Wr, Wb, Gr, Gb in the horizontal and vertical directions from the image sensor, and the correcting means synchronizes them. Color component signals Wr, Wb, Gr, Gb
It is advantageous that the correction coefficient is calculated based on each of the correction coefficients, and the matrix calculation means calculates the color signals R, G, B from the corrected color component signals Wr, Wb, Gr, Gb by a predetermined calculation formula. Is.

In this case, the correction means includes the first color component signal Wb and the second color component signal of the synchronized n scanning lines.
Synchronized with the first horizontal addition means for adding Gr (n +
1) Second horizontal addition means for adding the third color component signal Wr and the fourth color component signal Gb of the scanning line, and the addition signal (Wb + Gr) from the first addition means and the second addition Comparison means for calculating the ratio Hn = (Wb + Gr) / (Wr + Gb) from the addition signal (Wr + Gb) from the means, and the color component of n scanning lines from the comparison result Hn from this comparison means The first correction coefficient k = (0.5 + 0.5Hn) for correcting the signals Wb, Gr, respectively, and the second correction coefficient for correcting the color component signals Wr, Gb of the (n + 1) scanning lines, respectively.
Coefficient calculation means for calculating the coefficient k (n + 1) = (0.5 + 0.5 / Hn).

On the other hand, the color filter may be a primary color filter containing red R, green G and blue B.

[0022]

According to the color signal conversion device in the single-plate color camera of the present invention, the color component signal transmitted through the filter having the predetermined color arrangement is detected by the image pickup device, and the color components are sequentially scanned for each scanning line. Output a signal. For example, the color component signals of the two pixels of the n horizontal lines and the color component signals of the two pixels of the (n + 1) horizontal line are synchronized by the synchronizing means and output as four types of color component signals. It The color component signals of each horizontal line are added by the horizontal addition means and supplied to the vertical comparison means. The comparing means calculates the ratio of the color component signals added to the n horizontal lines and the (n + 1) horizontal lines and outputs the ratio to the coefficient calculating means. The coefficient calculating means calculates a coefficient so that the values of the respective color component signals are averaged according to the ratio of the respective horizontal lines from the comparing means, and, for example, four types of signals are supplied to the respective horizontal scanning lines. Correct according to. The corrected color component signal is processed by a matrix calculation circuit according to a predetermined calculation, for example, R, G, B
Are converted into three types of color signals.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a color signal conversion device in a single plate type color camera according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the configuration of the main part of an embodiment of a single-plate color camera to which the color signal conversion device according to the present invention is applied. The color signal conversion device in the present embodiment, the synchronization unit 20 that synchronizes the color component signals from the color image sensor 10, the correction unit 30 that corrects the synchronized color component signals, the color component signal R, Converter for converting to G and B color signals
Including 40 and. It should be noted that FIG. 1 shows only the portion of the configuration of the single-plate color camera that is directly related to this embodiment, and the portion that is not directly related to this embodiment is omitted.

The details of each section will be described.
10 is a CCD (Charged
This is an image sensor in which a filter of a predetermined color array is mounted on a coupled device, and in particular, in this embodiment, an interline CCD for field-storage two-row mixed readout in which a complementary color filter shown in FIG. 2 is mounted is advantageously applied. . Specifically, in the complementary color filter shown in FIG. 2, for example, color filters of a combination of magenta Mg and cyan Cy, and green G and yellow Ye are alternately arranged in the horizontal direction in n horizontal scanning lines, and (n + 1) Magenta Mg and yellow on horizontal scan line
This is a complementary color filter in which color filters of a combination of Ye, green G, and cyan Cy are alternately arranged, and the horizontal scanning lines of each array are alternately arranged in the vertical direction.
The CCD in the image pickup device 10 has a first color component signal Wb in which magenta Mg and cyan Cy are mixed in n horizontal scanning lines,
Second color component signal Gr mixed with green G and yellow Ye
And are alternately output as a dot-sequential signal. In the (n + 1) horizontal scanning line, the third mixture of magenta Mg and yellow Ye
Of the color component signal Wr and the fourth color component signal Gb in which green G and cyan Cy are mixed are alternately output as a dot-sequential signal.

The synchronizing section 20 is a timing processing circuit for synchronizing dot-sequential color component signals output from the image pickup device 10 between pixels adjacent in the horizontal and vertical directions,
In this embodiment, the color component signals Wr, Gb from the n horizontal scanning lines
2 pixels and the color component signal W from the (n + 1) horizontal scanning line
2 pixels of b and Gr, 4 pixels in total, are sequentially synchronized and output.
More specifically, the synchronization unit 20 includes an analog / digital (A / D) converter 22 and a horizontal delay circuit (1H) as shown in FIG.
DL) 24 and a synchronization circuit 26. The analog / digital converter 22 includes color component signals Wr, Wb, Gr, Gb from the image sensor 10.
Is a signal conversion circuit for converting each into, for example, 8 to 10 bits of digital data. The output of the A / D converter 22 is supplied to the one horizontal delay circuit 24 and the synchronization circuit 26.

The 1-horizontal delay circuit 24 is a line buffer circuit that stores digital data of 1 horizontal scanning line, and is composed of, for example, a FIFO memory, and is supplied to the synchronization circuit 26 via the A / D converter 22. The color component data of the pixels of the previous line corresponding to each of the current horizontal scanning lines is output dot-sequentially in the order of input. Synchronization circuit 26
Is the color component data of the direct color component data from the A / D converter 22 and the color component data from the one horizontal delay circuit 24, which are sequentially sampled every two pixels, and the color components of a total of four pixels adjacent in the horizontal direction and the vertical direction. It is a circuit that outputs data by synchronizing with a multiplexer or the like. For example, in the (n + 1) horizontal scanning line from the A / D converter 22, the adjacent color component signals Wr, Gb
, And at that time, the adjacent color component signals Wb, Gr in n horizontal scanning lines from one horizontal scanning line 26 are detected, and these four pixels Wb, Wr, Gr, Gb adjacent in the horizontal and vertical directions are detected. The signals are sequentially synchronized by a multiplexer or the like and output to the correction unit 30.

The correction unit 30 is configured to synchronize the color component signals Wr, W
This is a signal processing circuit for outputting a predetermined correction to b, Gr, Gb, and in particular, in the present embodiment, two horizontal components corresponding to the total pixel values of four types of color component signals Wr, Wb, Gr, Gb are synchronized. This is a circuit that sets a correction coefficient so that the respective color component signals are averaged according to the signal ratio of the scanning line, and corrects the synchronized respective color component signals. Specifically, the sum of the values of the adjacent color component signals of pixels arranged in the horizontal direction and the sum of the values of the color component signals at the same horizontal position on the next horizontal line are compared to obtain the average value. Like the nth line
A correction coefficient for reducing the color moiré is obtained by correcting the (n + 1) th line, and each color component signal is corrected by this. In particular, when the pixel values on the n-th line and the (n + 1) -th line are different, the simultaneous output of each of the n-th lines is calculated by the following equation (4) so that it becomes the average value. The correction coefficient k (n + 1) calculated by the following equation (5) is added to each synchronized output of the (n + 1) th line.

[0028]

[Equation 4]

[0029]

(Equation 5)

However, Hk = (Wr + Gb) / Wb + Gr). That is, the incident energy of all pixels of the four types of color component signals that are synchronized is expressed as a luminance signal of (Wb + Gr + Gb + Wr) = (2R + 3G + 2B). By taking the pixel ratio in the scanning line, the same brightness and the same color are applied in the vicinity of these four synchronization signals, so that the respective pixels are averaged.

Specifically, the correction unit 30 of this embodiment is similar to that shown in FIG.
As shown in FIG. 3, it includes a first horizontal addition circuit 32, a second horizontal addition circuit 34, a vertical comparison circuit 36, and a correction coefficient calculation circuit 38. The first horizontal addition circuit 32 is an arithmetic circuit that receives the color component signals of two pixels in the horizontal scanning line of the previous line from the synchronized color component signals and adds them. Similarly, the second horizontal addition circuit 32 is an arithmetic circuit that receives and adds the color component signals of the two pixels in the horizontal scanning line at the present time. For example, when the color component signals of the n horizontal scanning lines and the (n + 1) horizontal scanning lines are synchronized, the first horizontal addition circuit 32 receives the color component signals Wb, Gr and adds them to obtain a first horizontal addition signal. The addition signal (Wr + Gb) is calculated, and the second horizontal addition circuit 34 receives the color component signals Wb and Gr and calculates the second addition signal (Wb + Gr) by adding them, and outputs them. .

The vertical comparison circuit 36 includes a first addition signal and a second addition signal.
Is a calculation circuit for calculating the ratio of the addition signal of, and is formed by, for example, a division circuit or a look-up table in which reciprocal values are stored in advance and an integration circuit. Particularly, in the present embodiment, the first ratio obtained by dividing the addition result of the first horizontal addition circuit 32 by the addition result of the second addition circuit 34 and the addition result of the second addition circuit 34 to the first The second ratio divided by the addition result of the adder circuit 32 is output. Specifically, for example, an addition signal of color component signals of n horizontal scanning lines
The addition signals (Wb + Gr) of (Wr + Gb) and (n + 1) horizontal scanning lines are received from the addition circuits 32 and 34, and the first ratio Hn = (Wr
+ Gb) / (Wb + Gr) and the second ratio 1 / Hn = (Wb + Gr) / (Wr + Gb) are calculated.

The coefficient calculation circuit 38 is an arithmetic circuit that calculates a correction coefficient based on the comparison result from the comparison circuit 36 and corrects the synchronized color component signals from the synchronization section 20 with the correction coefficient. . Specifically, from the first ratio Hn to the color component signals Wb, Gr from the synchronized n horizontal scanning lines,
The first correction coefficient kn = (0.5 + 0.5 · Hn) corresponding to (4) is calculated and integrated, and the second correction coefficient kn = (0.5 + 0.5 · Hn) is added to the color component signals Wr, Gb from the (n + 1) horizontal scanning line. From the ratio 1 / Hn, calculate the second correction coefficient k (n + 1) = (0.5 + 0.5 / Hn) corresponding to the above equation (5),
Each is integrated and output to the conversion unit 40.

The conversion section 40 includes a corrected color component signal Wb, Gr,
It is a signal processing circuit including a matrix operation circuit 42 for performing a predetermined operation on Wr, Gb to convert it into R, G, B signals. As the matrix arithmetic expression of the present embodiment, the following arithmetic expressions (6) to (8) including arbitrary constants α, β, γ are advantageously applied similarly to the above-mentioned expression (1).

[0035]

(Equation 6)

In this case, the matrix coefficients α, β, γ
May be a coefficient value set so as to be reproduced as a desired color when a solid picture, that is, an image with a low spatial frequency is captured. For example, if the white color of Betanuri is illuminated by a predetermined light source, the ratio of each color signal of R, G, B showing white as output is set so as to meet the above equations (2) and (3). Good to do. Therefore, it is a fixed value for a constant light source color temperature.

According to the color signal conversion device in the single-plate color camera having the above-described configuration, in the operating state, first, the respective color component signals detected by the color image pickup device 10 are detected for each scanning line. For example, Wb, Gr, ...
.., or Wr, Gb, ... Are supplied to the synchronization unit 20 in a dot-sequential manner. In this case, the color component signal Wb is a signal in which magenta Mg and cyan Cy are pixel-mixed, and the color component signal Gr is a signal in which green G and yellow Ye are pixel-mixed, and the same scan line, for example, n scan lines. Is a color component signal of. The color component signal Wr is a signal in which magenta Mg and yellow Ye are pixel-mixed, and the color component signal Gb is a signal in which green G and cyan Cy are pixel-mixed. For example, the color components of (n + 1) scanning lines It is a signal.

Next, in the synchronizing section 20 which has received the dot-sequential color component signals, the respective color component signals are digitally converted by the A / D converter 22 and directly to the synchronizing circuit 26 and 1
It is supplied with a delay of one horizontal scanning line via the horizontal delay circuit 24. As a result, the synchronization circuit 26 is provided with, for example, n
The color component signals Wb, Gr, Wb, ... Of the scanning line and the color component signals Wr, Gb, Wb, ... Of the (n + 1) scanning line are sequentially supplied in synchronization.

Next, the synchronizing circuit 26 detects, for example, the adjacent color component signals Wb and Gr in the n scanning lines from the sequentially supplied color component signals for every two pixels, and responds to this (n +1) Detect adjacent color component signals Wr, Gb in every 2 pixels in the scanning line, and select these four types of color component signals Wb, Gr, Wr, Gb
Are supplied to the horizontal addition circuits 32 and 34 and the coefficient calculation circuit 38 of the correction unit 30 after being synchronized by a multiplexer or the like. In this case, the color component signals Wb and Gr of the n scanning lines are supplied to the first horizontal addition circuit 32, and (n +
1) The color component signals Wr, Gb of the scanning line are supplied, and the four kinds of color component signals Wb, Gr, Wr, Gb are supplied to the coefficient calculating circuit 38, respectively.

As a result, the color component signals Wb, Gr of the synchronized n scanning lines are added by the first horizontal addition circuit 32 and are added to the vertical comparison circuit 36 as the first addition signal (Wb + Gr). Supplied. Similarly, the color component signals Wr, Gb of the synchronized (n + 1) scanning lines are added by the second horizontal addition circuit 34 and supplied to the comparison circuit 36 as the second addition signal (Wr + Gb). To be done. A comparison circuit receiving the first addition signal and the second addition signal
36 takes these ratios and calculates the first ratio Hn = (Wr + Gb) / (Wb + G
r) and the second ratio 1 / Hn = (Wb + Gr) / (Wr + Gb) are supplied to the correction coefficient calculation circuit 38, respectively.

Next, in the correction coefficient calculation circuit 38, the first correction coefficient kn = (0.5 + 0.5Hn) for correcting the color component signals of the n scanning lines from the first ratio Hn and the second ratio 1 From / Hn (n +
1) A second correction coefficient k (n + 1) = (0.5 + 0.5 / Hn) for correcting the color component signal of the scanning line is calculated. Next, the correction coefficient calculation circuit 38 integrates the first correction coefficient kn into the color component signals Wb, Gr of the n scanning lines received from the synchronization circuit 26, and further adds the second correction coefficient k (n + 1 ) Is added to the color component signals Wr, Gb of the (n + 1) scanning line, and these are supplied to the conversion unit 30.

The color component signals thus corrected are the first addition signal (Wb + Gr) of n horizontal scanning lines and the second addition signal (Wb + Wr) of (n + 1) horizontal scanning lines. Are the same filter combination, that is, (Mg + Cy + G + Ye). In this case, magenta Mg is (r + b), cyan Cy is (g + b), yellow
Ye can be expressed as (r + g), so (Mg + Cy + G + Ye) =
(2b + 3g + 2r), which can be considered to represent the luminance signal component. Therefore, in this embodiment, the color signal is obtained by considering that the ratio of the luminance signal and the color difference signal is locally constant. That is, comparing the sum of the output values of adjacent color component signals of pixels arranged in the horizontal direction with the sum of the output values of color component signals of the same horizontal position on the next horizontal line,
The n-th line and the n + 1-th line are corrected so that the average value is obtained. As a result, color moire is reduced. That is, when the values of the nth line and the (n + 1) th line are different, the first correction coefficient kn is added to each color component signal of the nth line so that the average value is obtained, and (n + 1) The second correction coefficient k (n + 1) is added to each color component signal of the line.

For example, the first correction coefficient kn is kn = 0.5 + 0.5.Hk = 0.5 + 0.5. (Wr + Gb) / (Wb + Gr) = 0.5 (Wb + Gr + Gb + Wr) / (Wb + Gr), which is represented by the ratio of the pixels of the n-line color component signal to the total incident energy of the synchronized color component signals, and the corrected color component signals Wb, Gr are four types. The values are averaged over the pixels.

Similarly, the second correction coefficient k (n + 1) is k (n + 1) = 0.5 + 0.5 / Hk = 0.5 + 0.5 (Wb + Gr) / (Gb + Wr) = 0.5 ( Wb + Gr + Gb + Wr) / (Gb + Wr), which is expressed by the ratio of the pixels of the (n + 1) line color component signal to the incident energy of all pixels of the four types of color component signals. The color component signals Wr and Gr corrected by the above are values averaged on four types of pixels. Therefore,
In the present embodiment, the same luminance and the same color are applied in the vicinity of these four color component signals, so that moire between the vertical directions is reduced.

For example, as shown in FIG. 3, unless such a correction is performed, the vertical relationship of the pixel arrangement is switched for each horizontal line adjacent in the vertical direction depending on, for example, the combination of the color component signals Wb and Gb. The following color moire occurred. For example, when an object with a density gradient is imaged, the color component signal is
If Wb is on the upper side and Gb is on the lower side, RGB color signal values calculated by the respective output values are obtained. Next, in even-numbered horizontal lines, the color component signal Gb is on the upper side and Wb is on the lower side. However, since the density gradient is explained as an example with a constant value, a value different from the RGB color signal value at the time of an odd number line appears when performing the same calculation, and a striped line is generated for each even and odd line. It appears as moire. This is because strong light enters the color component signal Wb on the odd-numbered lines, but strong light enters the color component signal Gb on the even-numbered lines, and therefore different colors appear due to different ratios. Therefore, if a method of taking an average value like this method is adopted, striped moire does not occur because the same hue appears in the same hue as in this example.

Next, the color component signal W corrected as described above
b, Gr, Gb, Wr are supplied to the matrix operation circuit 42. In the matrix calculation circuit 42, matrix coefficients α, β,
γ is set so that each color signal of R, G, B becomes white as an output as an output when illuminating the white of Betanuri with a predetermined light source. Therefore, it is possible to obtain a color signal having high color reproducibility without moire as well as a light source having the same color temperature as the predetermined light source. Further, since the respective color component signals are averaged and supplied as described above, even when imaged by light sources having different color temperatures, the density as described above is hardly affected by the color temperature. It is possible to obtain a color signal with high color reproducibility without causing moire in the hue according to the gradient.

Further, in the case of the present embodiment, since the sum of the signals of the adjacent two horizontal pixels is used and the coefficient is obtained by using the ratio of the signals of the adjacent two vertical lines, the configuration of the minimum number of pixels is used. Color signals can be obtained with 2x2 pixels, which has the advantage of not lowering the resolution. In addition, there is also an advantage that the calculation can be carried out by shifting by one horizontal pixel, such as (Mg + G) and (G + Mg).

As described above, the color component signals for every four pixels are sequentially arranged in the horizontal direction in the n line and the (n + 1) line by two pixels in total.
Based on Wb, Gr, Wr, Gb, respective R, G, B signals are sequentially calculated and output. In this case, each pixel is calculated and corrected with a different correction coefficient depending on the position of the pixel in the horizontal direction,
The R, G, B color signals are output without causing moire in the hues corresponding to the respective color densities. When the calculation of n line and (n + 1) line is completed, (n + 2) and (n + 3)
A color signal is calculated from the color component signal of the line, and this operation is repeated to obtain R, G, B image signals representing the captured subject image.

The luminance signal and the color difference signal can be obtained by converting the R, G, B color signals from the matrix calculation circuit 42 by, for example, a known NTSC encoder.

Further, in the above embodiment, an example in which magenta Mg, green G, cyan Cy, and yellow Ye is applied to the color filter has been described, but other combinations may be used in the present invention. For example, as shown in FIG. 4, instead of one complementary color filter, a primary color filter may be divided into some pixels and assigned. In the above embodiment, as shown in FIG. 2, n lines and (n +
1) Magenta Mg and green G are arranged on the same line in the line, cyan Cy and yellow
Although the positions of Ye are alternately arranged, in the present invention, as shown in FIG. 5, for example, magenta Mg so that the upper and lower lines become the same color filter constituent element.
A checkered complementary color filter in which the positions of and green G are alternately arranged may be applied.

Further, in the above-mentioned embodiment, the color camera using the field storage color difference line sequential system has been described as an example, but the frame storage color difference line sequential system may be applied in the present invention. In this case, as shown in FIG. 7, interlaced scanning is performed in the field accumulation method in which a photosensitive pixel is arranged for each color filter pixel, and the color filter 2
The present invention can be applied to any case in which a non-interlaced scan is performed in a frame storage system in which photosensitive pixels are arranged in each row.

[0052]

As described in detail above, according to the color signal conversion device in the single plate type color camera of the present invention,
The correction coefficient is calculated according to the ratio of the pixels of each horizontal line between the same color components using the color component signal outputs that are adjacent in the horizontal and vertical directions, so that the ratio is independent of the change in color temperature. It is possible to obtain a color signal with almost no occurrence of color moire as a result. Therefore, it is not necessary to correct the photosensitivity of each color filter in advance according to the color temperature, a circuit for storing those values is not necessary, and the effect of saving the time to measure the color temperature in advance can be reduced. Play. Further, it is possible to have an advantage that it is not necessary to consider the variation of the color filter depending on the production lot.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a single-plate color camera to which a color signal conversion device in a single-plate color camera according to the present invention is applied.

FIG. 2 is a schematic diagram showing an example of a color filter applied to the embodiment of FIG.

FIG. 3 is a diagram showing a process of forming a striped moire.

FIG. 4 is a diagram showing an example of a combination of primary color filters applied to the present invention.

FIG. 5 is a diagram showing an example of another complementary color filter applied to the present invention.

FIG. 6 is a diagram for explaining another pixel-mixing readout method applied to the present invention.

[Explanation of symbols]

 10 Color image sensor 20 Synchronizing unit 22 Analog-to-digital converter 24 1 Horizontal delay circuit 26 Synchronizing circuit 30 Correction unit 32 First horizontal addition circuit 34 Second horizontal addition circuit 36 Vertical comparison circuit 38 Correction coefficient calculation circuit 40 Conversion Part 42 Matrix operation circuit

Claims (5)

[Claims] 1. A color signal conversion device in a single-chip color camera for converting a plurality of color component signals sequentially output from a single image pickup device equipped with a filter of a predetermined color array into a desired color signal. The apparatus includes a synchronization unit that synchronizes the color component signals sequentially output from the image sensor for each of a plurality of pixels that are adjacent in the horizontal direction and the vertical direction, and a plurality of colors that are synchronized by the synchronization unit. A correction coefficient is calculated on the basis of the component signal, and the correction coefficient corrects the color component signal from the synchronization means by the correction coefficient, and a predetermined calculation is performed on the corrected color component signal from the correction means. And a matrix operation means for obtaining a desired color signal, wherein the correction means is configured to adjust the color of each color according to the ratio of the color component signals in the vertical direction to the total pixel value of the plurality of synchronized color component signals. Minute signal calculates a correction coefficient such that the averaged value, the color signal converting apparatus in the single-plate type color camera and correcting the respective color component signals by the correction factor. 2. The color signal conversion apparatus according to claim 1, wherein the correction unit adds horizontal color component signals among a plurality of synchronized color component signals, and the horizontal addition unit. A single-plate color having a vertical comparison means for taking a ratio in the vertical direction from the addition result of the addition means and a coefficient calculation means for calculating a correction coefficient for each horizontal scanning line from the comparison result of the comparison means. Color signal conversion device in camera. 3. The color signal conversion device according to claim 1, wherein the color filter includes four types of complementary color filters of magenta Mg, cyan Cy, green G, and yellow Ye, and the image sensor is , N horizontal lines (n is a natural number)
At the first color component signal Wb in which magenta Mg and cyan Cy are mixed, and the second in which green G and yellow Ye are mixed
And the third color component signal Wr in which magenta Mg and yellow Ye are mixed in the (n + 1) horizontal line and the fourth color in which green G and cyan Cy are mixed. Outputting the component signal Gb alternately, the synchronizing means synchronizes adjacent color component signals Wr, Wb, Gr, Gb in the horizontal and vertical directions from the image sensor, and the correcting means synchronizes them. Based on the color component signals Wr, Wb, Gr, Gb thus obtained, the correction coefficient is obtained and corrected respectively, and the matrix calculation means is
A color signal conversion device in a single-chip color camera, characterized in that color signals R, G, B are obtained from a corrected color component signal Wr, Wb, Gr, Gb by a predetermined arithmetic expression. 4. The color signal conversion device according to claim 3, wherein the correction means includes synchronized color component signals Wr, Wb, G.
Of the r and Gb, the first color component signal Wb of the n horizontal lines and the second
First horizontal addition means for adding the color component signals Gr of
1) Second horizontal addition means for adding the third color component signal Wr and the fourth color component signal Gb of the horizontal line, the addition signal (Wb + Gr) from the first addition means and the second The addition signal (Wr + Gb) from the addition means of and their ratio Hn = (Wb + Gr) / (Wr + Gb
b) and the first correction coefficient k = (0.5 + 0.5Hn) and (1) for correcting the color component signals Wb, Gr of the n horizontal lines from the comparison result Hn from the comparison means. n +
1) A coefficient calculating means for calculating a second correction coefficient k (n + 1) = (0.5 + 0.5 / Hn) for correcting the color component signals Wr, Gb of the horizontal line, respectively. Color signal converter for single-panel color camera. 5. The color signal conversion device according to claim 1, wherein the color filter is a primary color filter containing red R, green G, and blue B. Signal converter.