JPS61161888A - Color error correcting method - Google Patents

Abstract

PURPOSE:To decrease the vertical color error of a single plate color camera by comparing two color difference signals with two color difference signals to delay two horizontal scanning periods respectively and replacing the color difference signal obtained by synchronizing with the color difference signal before synchronization. CONSTITUTION:A line sequential color difference signal inputted to an input terminal A is inputted to 1H change-over circuit 8C and 1H delay circuit 8A. The output of 1H delay circuit 8A is inputted to 1H change-over circuit 8C and 1H delay circuit 8B, and two color difference signals synchronized from 1H change-over circuit 8C are obtained. Two color difference signals go to be respectively 2H delay signal as per 1H delay circuits 8D and 8E, and 8F and 8G. Next, the difference between two synchronized color difference signals and two 2H delayed color difference signals is taken by subtracters 8T and 8U, converted through rectifier circuits 8H and 8I, and comparators 8J and 8K to a binary signal. By the binary signal, the occurrence of the color error is detected, analog switches 8R and 8S are changed over, and replaced to the color difference signal before 2H.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color error correction method that can be used in a single-chip color video camera.

BACKGROUND OF THE INVENTION In recent years, there have been remarkable improvements in the image quality of single-chip color video cameras. In particular, single-chip color video cameras with reduced vertical color errors are attracting attention. This is a line-sequential color difference signal obtained every horizontal period.

This is because two consecutive color difference signals are obtained by using a delay of one horizontal period.

The conventional single-chip color video camera as described above will be described below with reference to one drawing.

FIG. 3 shows a block diagram of a single-chip color video camera. The output signal of the solid-state imaging plate (1) passes through a wideband low-pass filter (2) to obtain a luminance signal and input it to an encoder (10). In addition, the output signal of the solid-state image sensor (1) passes through a bandpass filter (3) that passes around a frequency that is half the horizontal drive frequency, and the high frequency component modulated by the mosaic color filter is separated here. Furthermore, a line-sequential color difference signal is obtained by a synchronous detection circuit (4).

The line-sequential color difference signal and the output signal of the solid-state image pickup plate (1) are passed through a narrow-band low-pass filter (6), and the obtained luminance signal is input to a white balance circuit (5). I get a signal. The obtained signals are input to two input terminals of the switch circuit (9), respectively, directly and via the one horizontal period delay circuit (8). Then, the line-sequential color difference signal is converted to 2 by the switch circuit (9).
This results in two simultaneous color difference signals. Further, said two simultaneous color difference signals are fed to an encoder (10) and converted into a standard color television signal. By the way, in the solid-state imaging plate (1), as shown in FIG.
It must be adjusted and installed to correspond to 1. That is, picture element A 11. A,, -,A,1. A,
, .

...A,, and color filter elements C1,, C1,...
C8□.

C, . . . Cmtt . . . are arranged in exact correspondence with each other.

After the light (13) from the subject passes through each color filter element C11, C, .
... A, 3 is irradiated and converted into a signal charge. When a field accumulation operation (References, Sone et al., "Single plate colorization method of field accumulation mode COD 117th magazine, 37.10, PP89-96, Oct. 1983) is performed, the first signal charge of the A field is In the horizontal scanning period,
A11 and All, A1□ and Ao, A1. and A. ,...
The signal charges of two picture elements are mixed and output as shown below. Furthermore, in the second horizontal scanning period, All and A4
, and A42, A23 and A43, ..., and in the third horizontal scanning period, As1 and A61, Ao and A, ..., As3
and A. .

. . . The signal charges of two picture elements are mixed and output. On the other hand, in field B.

Ao and A during the first horizontal scanning period. , AB and A31°A
, and A33,..., during the second horizontal scanning period, A41
and A,1,・A4. and A H1* A43 and A,,%
”-1, which is a different combination from the A field.
Signal charges for picture elements are mixed and output.

FIG. 5 shows the constituent units of a color separation filter using field accumulation mode. Cyan color transmission filter element C,,1,C1,,,C,,□,Yellow color transmission filter element C1,,,C13,,C,,,Magenta color transmission filter element C1! lj 14! s green transmission filter element C1Zt C141, (121) to (12
5) indicates each row.

As is well known, the cyan transmission filter element transmits blue and green primary color component light, the magenta color transmission filter element transmits blue and red primary color component light, and the yellow transmission filter element transmits red and green primary color component light. Let each light pass through.

Next, an explanation will be given of an output signal taken out from the solid-state image sensor equipped with the color separation filter shown in FIG.

FIG. 6(a) shows odd-numbered rows (for example, row (121) and row (1) in FIG.
22), which shows the signal output of (here, two lines are grouped together as an odd numbered line),
FIG. 6(b) similarly shows the even numbered rows (
Simultaneous reading of rows (123) and (124) in FIG. 5) signal output, and FIG.
Fig. 6(d) shows the signal output of even-numbered rows in the B field (simultaneous reading of rows (124) and (125) in Fig. 5).
The vertical axis represents the voltage V, and the horizontal axis represents the time t. However, for the sake of explanation, the output waveform is represented by R, G, and B for the primary color components of the color separation filter corresponding to each picture element, red, green, and blue, respectively. Ta.

In FIGS. 6(a) to (d), for example, in the A field odd rows, (Cy+Mg)-(Ye+G)==(R+G+
2B) - (R + 2G) ~ 28-G (Figure 6 (a)),
For even rows, (Cy+G)-(Ya+Mg)=(2G+
A color difference signal of B)-(2R+G+B)=G-2R (FIG. 6(b)) is obtained.

Similarly, in field B, in odd rows, (Mg+Cy)-
CG+Ya)= (R+G+2B) −(R+2R)=
28-G (Figure 4(C)), in even rows, (a+cy)
(Mg+Ye)=(2G+B)-(2R+G+B)=G
A color difference signal of -2R (FIG. 4(d)) is obtained.

On the other hand, the luminance signal Y is obtained by passing the signals shown in FIGS. 6(a) to 6(d) through a low-pass filter.

The luminance signals Y of all rows are Y=2R+3G+2B.

The color difference signals 2B-G, G-2R are 28 for each odd and even row.
-G and G-2H are obtained repeatedly, so in one horizontal scanning period (hereinafter abbreviated as IH), 2B-G and G-2R color difference signals are simultaneously generated by the delay circuit and IH water horizontal changeover switch. make sure you get it.

The two color difference signals obtained as described above and the luminance signal Y described above are input to an encoder (10) to form a standard television signal.

Problems to be Solved by the Invention Here, in order to obtain two color difference signals, an IHH extension circuit and an IH
We use an H exchange switch to store items in piles. For this reason, when an object having different information in the vertical direction is imaged, a color error occurs in the vertical direction. For example, C81□ to C148, C11□ shown in FIG.
〜C14, is yellow, C151pC1, , C1□, C
1 and 2 are black, the signal becomes G-2R in the first row of the A field, 2B-G in the second row, and zero in the third row as shown in FIG. OH) is obtained. When this signal (OH) is delayed by IH using an IHH delay circuit, it becomes the signal (IH) shown in Figure 8. When the two color difference signals are synchronized using the switch circuit (9) shown in Figure 3, one horizontal scanning period is obtained. 2 as shown by G-2R and 28-G in Figure 8.
Color difference signals can be obtained simultaneously. Here, two color difference signals (G-2R and 28-G in FIG. 8) are obtained simultaneously on the first and second lines, and yellow is reproduced.

In the fourth row, both color difference signals are zero, resulting in an achromatic color.

However, in the third row, only 2B-G color difference signals can be obtained.
This becomes a color error. This color error is the vertical color error of a single-chip color video camera, which has the disadvantage of significantly deteriorating the image quality.

In view of the above-mentioned drawbacks, the present invention provides a single-panel color video
It is an object of the present invention to provide a color error correction method that can reduce vertical color errors of a camera.

Means for Solving the Problem In order to solve this problem, the color error correction method of the present invention uses two color difference signals obtained by synchronizing color difference signals taken out line-sequentially, and 2 color difference signals each
The configuration is such that two color difference signals delayed by a horizontal scanning period are compared, and the color difference signal obtained by synchronization is replaced with the color difference signal before synchronization.

Effect: Since the synchronized signals are delayed by two horizontal scanning periods in this way, the color difference signal at the location where the color error occurs can be easily detected, and the color difference signal at the location can be replaced with the signal before synchronization. This allows color errors to be corrected.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a circuit implementing a color error correction method according to an embodiment of the present invention, and FIG. 2 is a signal timing diagram thereof. The circuit shown in FIG. 1 replaces the color difference signal synchronization circuit composed of an IHH extension circuit (8) and a switch circuit (9) in the block diagram of a single-chip color video camera shown in FIG. That is, IH
H extension circuit (8A) (8B) (8D) (8E) (
8F) (8G), LH switching circuit (8C), rectifier circuit (8H) (8I), comparator (8J) (8K
), Inverter (8L) (8M) (8N), NAN
D gate (8P) (8Q), analog switch (8R
) (8S), subtractor (8T) (8U).

The line-sequential color difference signal with white balance in Figure 3 is
Input to input terminal (A) in Figure 1 (Figure 2 (a))
, the next input line sequential color difference signal is sent to the IHH switching circuit 8C.
) and is input to the LHH extension circuit (8A).

Signal passing through IHH extension circuit (8A) (Fig. 2(b))
One side is input to the IHH conversion switch (8C), the other side is further input to the IHH delay circuit (8B), and the 2H delay band (
Figure 2 (b')). Two simultaneous color difference signals G-2R, 2B-G (
Figure 2 (c) (d)) In other words, G-2R in the third row
It can be seen that the color is missing and a one-color error has occurred.

The two synchronized color difference signals are each passed through an IH delay circuit (
8D) and (8E), and (8F) and (8G).

1 which becomes the 2H delayed color difference signal (Figure 2 (e) (f))
Next, the two simultaneous color difference signals (Fig. 2(c) (d)
) )and.

Two color difference signals delayed by 2H (Fig. 2(e) (f
)) respectively using a subtractor (8T) (8T),
The obtained two color difference contour signals are each passed through a rectifier circuit (8H
) (8I) and comparators (8J) (8K) to convert into binary signals, the signals shown in FIGS. 2(g) and (h) are obtained.

Here, the comparator output in Figure 1 is E (Figure 2 (g)
(h)) and fH/2 signal F (Fig. 2 (i)), as shown in the truth table in Table 1, 8
A street condition exists. Of these, there is a signal.

The inverters (8L) (8M) (8N) and NA shown in Figure 1 make sure that E and F become "1", "0", and '0', respectively.
The input signal G to the analog switch (8R) (8S) in Figure 1 is detected by the ND gate (8P) (8Q).
(21!I(j)), H (Fig. 2(k)) is obtained. The input signal G to the analog switch (8R) is in the "1" state for the three rows where color errors occur. This signal G switches the analog switch (8R), as shown in Figure 2 (C).
When the signal in Figure 2 (b') is replaced, the outputs B and C of the analog switch (8R) (85) become G-2R in Figure 2 (vertical) and 28 in Figure 2 (■), respectively. -G. It can be seen that G-2R in the third row is filled in and the color error in the third row is corrected.

Table 1 2B-G correction also. When the position of the subject in Figure 7 moves upward by two pixels (Cz z□, C2□, C11□, C1° are yellow, C1,, c, ,, C,,,, C1,8,C,,
,,C, 42°C8□, C8° is black), 28 on the second line
-G is missing and a color error occurs in the second line. This time the first
The signals in the figure, E and F are “O”, “1” and ’1” respectively.
The color error can be corrected by detecting this, switching the analog switch (8S) in FIG. 2, and replacing the second line of 2B-G with the 2H delay signal in FIG. 2(b').

In this way, the color error can be corrected by detecting the point where the color error occurs through signal processing and replacing it with the color difference signal 2H earlier.

In this embodiment, a field accumulation mode colorization method of a single-chip color video camera was used, but the present invention is not limited to a single-chip color video camera and a field storage mode; Anything that has a function is fine1 For example, a single-tube color camera,
Frame accumulation mode can also be used in single-chip color video cameras.

Effects of the Invention As described above, the present invention replaces the color difference signal where a single color error occurs with the color difference signal before synchronization, so the color error can be corrected and a decline in image quality can be prevented.

Its practical effects are significant.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the correction circuit of the present invention, FIG. 2 is a signal timing chart for explaining the correction method, and FIG. 3 is a block diagram of a single-chip color video camera.
Fig. 4 is a configuration diagram of a color solid-state image pickup plate, Fig. 5 is a diagram explaining the constituent units of a color separation filter, Fig. 6 (a) is an odd-numbered row in the A field, (b) is an even-numbered row, and (C) 7(d) is a diagram explaining the odd rows in the B field, FIG. 7 is a diagram explaining the imaging state, and FIG. 8 is a timing diagram of the signal waveform. (8A) (8B) (8D) (8E) (8F)
(8G)... IH delay circuit, (8C)... IH switching circuit, (8H) (8I)... Rectifier circuit, (8J)
(8K)...Comparator, (8L) (8M) (8
N)...Inverter. (8R) (8S)...Analog switch agent
Yoshihiro Morimoto Greed < Kamo 2nd figure 9m ゛ Haruma 4th figure m5 figure fht figure (, l) (phantom tCλ (d) B74-L tt several strokes) ll7t-ILr
(10,000 lines) Figure 7

Claims (1)

[Claims] 1. Two color difference signals obtained by synchronizing the color difference signals taken out line-sequentially, and two color difference signals, respectively.
A color error correction method that compares two color difference signals delayed by a horizontal scanning period and replaces the color difference signal obtained by synchronization with the color difference signal before synchronization. 2. The two color difference signals obtained by synchronizing the two color difference signals and the two color difference signals obtained by delaying the two color difference signals by two horizontal scanning periods are each subtracted by a subtraction circuit, and the obtained bipolar two
Convert one color difference contour signal into two unipolar color difference contour signals using a rectifier circuit, operate an analog switch using the two unipolar color difference contour signals, and synchronize the color difference signals obtained by the synchronization. 2. The color error correction method according to claim 1, wherein the color error correction method comprises replacing the previous color difference signal with the previous color difference signal.