JP2951461B2 - Color video camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color video camera which eliminates a false color in a contour portion peculiar to a line-sequential color difference output type single-plate type image pickup device.

[0002]

2. Description of the Related Art A conventional color video camera 1 shown in FIG.
The image of the subject is formed on a single-chip solid-state imaging device 2 via an imaging lens system, and the image is sampled by a sample-and-hold circuit 3. The sample hold circuit 3
Pixel separation of a signal is performed by two kinds of sampling pulses φ1 and φ2 having opposite phases, and a sampling output is supplied to a color separation circuit 4. As shown in the figure, the solid-state imaging device 2 uses a complementary color filter in which four colors of magenta (Mg), green (G), cyan (Cy), and yellow (Ye) are arranged in a mosaic pattern. -Y,-(B-
Y) are output alternately and repeatedly. The modulated color signal component of the complementary color filter is (Mg + Ye)-(G + Cy) = 2R-G for the n-th line, and (G + Cy)-(Mg + Cy) = G-2B for the (n + 1) -th line. , 2R-G and G-2B, which can be regarded as equivalent to RY and-(BY), are line-sequential signals alternately output for each line. Color separation circuit 4
The low-pass filtering of the output of the solid-state imaging device 2 removes the modulated color signal component, whereby (Mg + Ye) + (G + Cy) = 2R + 3G + 2B from the n-th line and (G + Cy) + ( Mg + Cy) = 2R + 3G + 2B, and a luminance signal Y that can be equivalently regarded as Y = 0.3R + 0.59G + 011B is obtained.

However, the above-described color difference signals RY and BY are provided.
Are line-sequential signals obtained every other line, and it is necessary to fill gaps between lines. For this reason, a method of delaying the color difference signal of the current line by one line period and interpolating the same by line interpolation is used, and the synchronized color difference signals RY and BY are output from the color separation circuit 4 to the matrix. It is supplied to the circuit 5. The matrix circuit 5 generates three primary color signals R, G, B from the luminance signal Y and a pair of color difference signals RY, BY by matrix operation. The three primary color signals R, G, and B obtained from the matrix circuit 5 are subjected to signal processing such as white balance control and gamma correction in the subsequent process circuit 6.

[0004] Of the three primary color signals R, G, and B output from the process circuit 6, the green signal G is externally output directly through the buffer amplifier circuit 7, but the red signal R and the blue signal B are After adding the luminance contour signals in the color contour correcting addition circuits 8 and 9, the luminance contour signals are externally output via buffer amplifier circuits 10 and 11. Here, the luminance signal Y obtained from the color separation circuit 4 is sent to the luminance contour detection circuit 12, and the line delay circuit 12a outputs the luminance signal Y.
The luminance signal Y delayed by the line period is subtracted from the subtractor 12b.
, A luminance contour signal is generated by subtracting from the current luminance signal Y. The luminance contour signal thus obtained from the luminance contour detection circuit 12 is added to the red signal R and the blue signal B in the adders 8 and 9 in order to cancel the false color generated in the contour portion.

[0005]

The conventional color video camera 1 has a configuration in which line-sequential color difference signals RY and BY obtained from a single-chip solid-state imaging device 2 are synchronized by line interpolation. 4A and 4B, generation of a false color signal accompanying line interpolation is inevitable in a color contour portion where the signal correlation between the scanning lines is weakened. A configuration is adopted in which false colors are canceled by adding the luminance contour signals detected by the detection circuit 12. However, since the luminance contour signal obtained by performing first-order differentiation of the luminance signal Y is used as a color contour signal, there is a problem in the color contour correction accuracy. For example, the luminance does not change while there is a color change. In such a contour portion of the subject, since the brightness contour signal is not output, the color contour correction is not actually performed, or conversely, the contour of the subject in which only the brightness changes without a color change. In some cases, false color contour correction is performed, resulting in the addition of false color contours.

[0006]

According to the present invention, there is provided a color signal for outputting three primary color signals synchronized by line interpolation from line-sequential color difference signals obtained from a single-plate type image sensor. Processing means; a color contour extracting means for extracting a color contour signal from the green signal output by the color signal processing means; and a red signal and a blue signal output by the color signal processing means, and an edge portion of the green signal, respectively. A gate signal output means for outputting a gate signal when the edge portion has a shift of one line period; and a gate signal output means for receiving the gate signal output from the gate signal output means. And a color contour correcting means for correcting the color contour by adding a color contour signal to be shifted to the shifted red signal or blue signal.

[0007]

According to the present invention, a color contour signal is extracted from a green signal for three primary color signals synchronized by line interpolation from a line-sequential color difference signal obtained from a single-chip image sensor, and a red signal, a blue signal and the green signal are extracted. The edge portions of the signals are compared with each other, and if there is a shift of one line period in the edge portions, the color outline signal is added to the shifted red or blue signal to correct the color outline, thereby obtaining a line outline. A false color of a contour portion peculiar to the sequential color difference output type single-plate image sensor is eliminated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is a circuit diagram showing an embodiment of a color video camera according to the present invention, and FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG.

A video camera 21 shown in FIG. 1 has a color contour detecting circuit 22 for detecting a color contour from a green signal G, and a red signal and a blue signal for gated on a color contour signal outputted by the color contour detecting circuit 22. Pair of gate circuits 23 and 2
4 and the outputs of the pair of gate circuits 23 and 24 are supplied through low-pass filtering circuits 25 and 26, respectively, and added to the red signal R and the blue signal B, respectively.
8 and so on. The color contour detection circuit 22 generates a color contour signal by subtracting the green signal G delayed by one line period in the line delay circuit 22a from the current green signal G in the subtraction circuit 22b. Gate circuits 23, 24
Are supplied with gate signals from the gate control circuits 29 and 30 for detecting the false color position, respectively, and permit the passage of the color contour signal only at the false color position. Gate circuit 23
The gate control circuit 29 performs an exclusive OR operation of the red signal R and the green signal G, and uses the result of the logical operation as a gate signal, and compares the edge portions of the red signal R and the green signal G. Sometimes, a gate signal is output when there is a shift of one line period in the edge portion. The gate control circuit 30 for the gate circuit 24 performs an exclusive OR operation of the blue signal B and the green signal G and uses the result of the logical operation as a gate signal. When comparing the edge parts, 1
A gate signal is output when there is a line period shift.

In the embodiment, the solid-state image pickup device 2, sample and hold circuit 3, color separation circuit 4, matrix circuit 5
And the process circuit 6 constitute color signal processing means, the color contour detection circuit 22 serves as a color contour extraction means, the gate control circuits 29 and 30 serve as gate signal output means, and the gate circuits 23 and 24 serve as low-level signals. The band-pass filters 25 and 26 and the adders 27 and 28 constitute color contour correction means, respectively.

By the way, the generation pattern of the false color signal can be classified into four patterns shown in FIGS. FIG. 2A shows that the rising edge of the green signal G coincides with the rising edge of the blue signal B, but the rising edge of the red signal R is delayed by one line period, and the rising edge of the green signal G coincides with the falling edge. This is a pattern in which the falling edge of the red signal R matches, but the falling edge of the blue signal B is delayed by one line period. FIG. 2B shows a green signal G and a blue signal B.
Coincides with both rising and falling edges,
This is a pattern in which only the red signal R is delayed by one line period in both the rising edge and the falling edge. FIG.
(C) shows the rising edge of the green signal G and the red signal R
Rising edge of the blue signal B is delayed by one line period, and the falling edge of the green signal G matches the falling edge of the blue signal B, but the rising edge of the red signal R The falling edge is a pattern when it is delayed by one line period. FIG. 2D shows that the rising edge and the falling edge of the green signal G and the red signal R match, but the blue signal B
Is a pattern when both the rising edge and the falling edge are delayed by one line period.

For these four patterns, the color contour detection circuit 22 outputs a green signal G as shown in FIG.
At the rising edge and the falling edge of, a color contour signal having positive and negative polarities and lasting for one line period is obtained. These color contour signals pass through gate circuits 23 and 24 that are controlled to be opened and closed by gate signals from gate control circuits 23 and 24, and after noise components are removed by low-pass filtering circuits 25 and 26, respectively, the signals are added. The signals are sent to the circuits 27 and 28.

That is, in the pattern shown in FIG. 2A, the gate circuit 23 first opens the gate in response to the output of the gate control circuit 29.
The color contour signal is added to the rising portion of the red signal R which is delayed from the other color signals by the line period as shown by the dashed line in FIG. 2A, and all the rising edges of the three primary color signals match. Become. Then, since the gate circuit 24 opens the gate in response to the output of the gate control circuit 30, the falling edge of the blue signal B is delayed by one line period from the other color signals, as shown in FIG.
As shown by the two-dot chain line in (A), the color contour signals are added with a negative polarity, whereby the falling edges of the three primary color signals all coincide.

In the pattern shown in FIG. 2B, first, the gate circuit 23 opens the gate in response to the output of the gate control circuit 29, so that the rising edge is delayed by one line period from the other color signals. The color contour signal is added to the rising portion of the red signal R as shown by the dashed line in FIG. 2B, and the rising edges of the three primary color signals are all coincident. Next, since the gate circuit 23 opens the gate again upon receiving the output of the gate control circuit 29,
A color contour signal having a negative polarity is added to the falling portion of the red signal R whose falling edge is delayed by one line period from the other color signals, as shown by a two-dot chain line in FIG. As a result, all the falling edges of the three primary color signals coincide.

In the pattern shown in FIG. 2C, since the gate circuit 24 first opens the gate in response to the output of the gate control circuit 30, the rising edge is delayed by one line period from the other color signals. The color contour signal is added to the rising portion of the blue signal B as shown by the one-dot chain line in FIG. 2C, and the rising edges of the three primary color signals are all coincident. Then, since the gate circuit 23 opens the gate in response to the output of the gate control circuit 29, the falling edge of the blue signal B whose falling edge is delayed by one line period from the other color signals is shown in FIG. C)
As shown by the two-dot chain line, the color contour signals are added with negative polarity, whereby the falling edges of the three primary color signals are all coincident.

Further, in the pattern shown in FIG. 2D, since the gate circuit 24 first opens the gate in response to the output of the gate control circuit 30, the rising edge is delayed by one line period from the other color signals. The color contour signal is added to the rising portion of the blue signal B as shown by the dashed line in FIG. 2D, and the rising edges of the three primary color signals are all coincident. Next, the gate control circuit 30
2D, the gate circuit 24 opens the gate again, so that the falling edge of the red signal R whose falling edge is delayed by one line period from the other color signals is shown in FIG.
As shown by the two-dot chain line, the color contour signals are added with negative polarity, whereby the falling edges of the three primary color signals are all coincident.

As described above, the color video camera 21
By extracting a color contour signal from a green signal G that is almost evenly included in the imaging signals of all subjects, it is possible to capture a color contour that cannot be captured from a luminance contour without leaking, In a contour part of a subject in which luminance does not change while there is a change, color contour correction is not performed because a luminance contour signal is not output, or conversely, only luminance changes without color change. It is possible to prevent a disadvantage that a false color contour is added due to erroneous color contour correction in a contour portion of a simple subject, and an edge portion of a red signal R and a blue signal G with respect to a green signal G from which a color contour is extracted. Detect the deviation of
If there is a shift in the edge portion, this offsets with the color contour signal before generating a false color contour.
, The outline of the red signal R and the outline of the blue signal B can be accurately aligned, whereby false color of the outline part peculiar to the line sequential color difference output type solid-state imaging device 2 can be accurately eliminated.

[0018]

As described above, the present invention extracts a color contour signal from a green signal for three primary color signals synchronized by line interpolation from a line-sequential color difference signal obtained from a single-chip image sensor. The red signal and the blue signal are compared with the edge portion of the green signal, and when there is a shift of one line period in the edge portion, a color contour signal is added to the shifted red signal or the blue signal to obtain a color. Since the contour is configured to be corrected, the color contour signal is extracted from the green signal that is almost evenly contained in the imaging signals of all subjects, so that the color contour that cannot be captured from the luminance contour can be captured without leaking. As a result, for example, as in a conventional color video camera in which a color contour is corrected using a luminance contour signal, an object in which the luminance does not change while the color is changed is provided. In the contour part of the body, the color contour correction is not performed because the luminance contour signal is not output, or conversely, in the contour part of the subject where only the luminance changes without color change, the wrong color It is possible to eliminate the inconvenience of adding false color contours by contour correction, and to detect the deviation of the edge part between the red signal and the blue signal with respect to the green signal from which the color contour is extracted, and if there is a deviation in the edge part Since this cancels out with a color outline signal before a false color outline is generated, it is possible to accurately align the outlines of the red signal and the blue signal with respect to the green signal, thereby providing a line-sequential color difference output type single-chip image sensor. An excellent effect is achieved such that false colors in a specific contour portion can be accurately eliminated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a video camera according to the present invention.

FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG.

FIG. 3 is a circuit diagram showing an example of a conventional color video camera.

FIG. 4 is a diagram for explaining generation of a false color in the color video camera shown in FIG. 3;

[Explanation of symbols]

 Reference Signs List 2 solid-state imaging device 3 color signal processing means (sample hold circuit) 4 color signal processing means (color separation circuit) 5 color signal processing means (matrix circuit) 6 color signal processing means (process circuit) 21 color video camera 22 color contour extraction Means (color contour detection circuit) 23, 24 Color contour correction means (gate circuit) 25, 26 Color contour correction means (low-pass filtering circuit) 27, 28 Color contour correction means (addition circuit) 29, 30 Gate signal output means ( Gate control circuit)

Claims (1)

(57) [Claims] 1. A color signal processing means for outputting three primary color signals synchronized by line interpolation from a line-sequential color difference signal obtained from a single-chip image sensor, and a color contour from a green signal output by the color signal processing means. A color contour extracting means for extracting a signal; and a red signal and a blue signal output by the color signal processing means, respectively, and an edge portion of the green signal. A gate signal output unit that outputs a signal; and a gate signal output unit that operates upon receiving the gate signal output by the gate signal output unit, and adds a color outline signal output by the color outline extraction unit to the shifted red signal or blue signal. A color video camera, comprising: a color contour correcting means for correcting a color contour.