JPS6260389A - Method for processing signal of color solid-state image pickup device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of a voltage in a blue signal at the time of red image pickup and to obtain a satisfactory color reproducibility by electrically processing one color information signal among two types of color information signals and adding it to the other one. CONSTITUTION:A slice circuit 50 slices only the positive polarity part of a 2R-G chrominance signal from a switch changing over by 1H 37, and controls the gain of the output 44 to an appropriate value. A subtractor circuit 51 subtracts said gain from the 2B-G chrominance signal 43 from said switch 37 at every 1H. The output signal 45 of the subtractor circuit 51 and the 2R-G chrominance signal 42 from the switch 37 are led to an encoder 38 to obtain a composite video signal. Thus the occurrence 38 to obtain a composite video signal. Thus the occurrence of the voltage in the blue signal at the time of red image pickup can be suppressed, and the color reproducibility, especially when red based colors are picked up, can be drastically improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a signal processing method for improving color reproducibility of a color solid-state imaging device.

Conventional technology color solid-state imaging devices are disclosed in Japanese Patent Application No. 55-1949, for example.
No. 7, Patent Application No. 14821/1982, Patent Application No. 134/1982
As described in No. 57 and US Pat. No. 4,403,247, the pixels 11 of the solid-state image sensor are adjusted and mounted in a 1:1 correspondence with the color separation filter 12, as shown in FIG.

That is, pixel A11. Al1. ”', A21.A2
2. "', 'm, h and color filter elements C, 1, C12
, , , C21, C221, , C, , n are arranged in exact correspondence with each other. After passing through the color filter elements C11, C121, . . . Crnn, the external light 13 is transmitted to each pixel A11 . A1゜,...,A
mn is irradiated and converted into signal charges. The signal charge photoelectrically converted in each pixel is serially output from the output section to the outside via vertical transfer means and horizontal transfer means of the solid-state image sensor. The signals output in series from the solid-state image sensor are separated into a luminance signal component and a color signal component by a video signal processing circuit, and finally synthesized into a composite video signal, typically represented by the NTSC system.

Examples of a color separation filter and a video signal processing circuit are shown in FIGS. 4 and 5, respectively. As a driving method for a solid-state image sensor, a field storage mode is used.
No. 3457) is used.

In FIG. 4, Ye is a yellow light transmitting color filter element, Cy
is a cyan light transmitting color filter element, My is a magenta light transmitting color filter element, and G is a green light transmitting color filter element.

FIG. 5 is an example of a video signal processing circuit when the color solid-state image sensor equipped with the color filter shown in FIG. 4 is driven in field accumulation mode. A luminance signal component of the signal obtained from the solid-state image sensor 27 equipped with the color filter shown in FIG. The color signal component passes through the bandpass filter 3Q, the detection circuit 31, and the process circuit 32, and is output as a color signal 40 in which two types of color information are repeated line-sequentially every horizontal period (hereinafter abbreviated as 1H).

A color signal in which two types of color information are repeated line-sequentially every 1H is passed through a 1H delay circuit 36 to produce a color signal output 41 delayed by 1H. Color signal 40°41 changeover switch 3 every 1H
7, the simultaneous 2R-G color signal 4
2.2B-G color signal 43 can be obtained. These 2R-G color signals 42 and 2B-G color signals 43 are balanced-modulated by the encoder 38, combined with the luminance signal, and output as a composite video signal. White balance is performed in the process circuit 32 using a signal that has passed through the low-pass filter 33.

Problems to be Solved by the Invention Simultaneous 2R-G color signals 42.2B- in FIG.
The signal waveforms of the prototype circuit for the G color signal 43 are shown in Fig. 6 a and b.
Shown below. The horizontal axis represents time and the vertical axis represents voltage. The subject is a color par chart with a color temperature of 3200.

As shown in one horizontal period in FIG. 6, the signal output is arranged in the order of white, yellow, cyan, green, magenta, red, and blue from the left.

FIG. 6C shows a signal waveform for decoding the composite video signal output in FIG. 5 and causing a blue phosphor to shine on a color monitor. A vectorscope was used to observe the waveform and the blue signal was measured.

As can be seen from FIG. 6C, according to the present prototype circuit, an output of voltage A appears even in the red part of the color par chart, which should not contain a blue component. When red is imaged in this way, if voltage A is output to the blue signal,
When only the red phosphor should shine on a color monitor, the blue phosphor shines, resulting in poor red color reproducibility.

In view of the above drawbacks, the present invention provides a signal processing method for a solid-state imaging device that can suppress the generation of voltage during red imaging in a blue signal.

Means for Solving the Problems In order to solve the above problems, the signal processing method for a color solid-state imaging device of the present invention electrically processes one of two types of color information signals, With this configuration, voltage generation in the blue signal during red imaging can be suppressed, and good color reproducibility can be obtained.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining a signal processing method of a color solid-state imaging device according to the present invention.

In FIG. 1, numerals 27 to 43 have the same functions as those with the same numbers in FIG. 6, which shows a conventional example. 50 is a slice circuit which extracts only the positive polarity portion of the 2R-G color signal 43 of the switch 37 every 1H;
1 is a subtraction circuit that subtracts the output of the slice circuit 60 from the 2B-G color signal 43;

In this example, the image sensor has 490 vertical pixels;
Horizontal 382 Pixel Interline Transfer System % Formula % The operation of the signal processing circuit of the solid-state imaging device configured as described above will be described below.

FIG. 2 is a diagram showing signal waveforms at various parts of the signal processing circuit shown in FIG. 1. 2A and 2B are the 2R-G color signals 4 from the 1H switching switch 37 in FIG. 1, respectively.
2.2 The signal waveform of the B-G color signal 43, FIG. 2C shows the output waveform of the slice circuit 50, and FIG.

Further, FIG. 2e shows a signal waveform for decoding the composite video signal output in FIG. 1 and causing a blue phosphor to shine on a color monitor. A vector scope was used to observe the waveform and the blue signal was measured.

First, only the positive polarity portion of the 2R-G color signal 42 from the 1H changeover switch 37 shown in FIG. 2A is sliced in the slicing circuit 50 to obtain the waveform shown in FIG. 2C.

The gain of the output 44 of the slice circuit 60 is controlled to an appropriate value, and the subtraction circuit 51 subtracts it from the 2B-G color signal 43 from the changeover switch 37 every 1H. As a result, a waveform shown in FIG. 2d is obtained.

Output signal 45 of subtraction circuit 51 and 1H changeover switch 37
The 2R-G color signal 42 is guided to the encoder 38 to obtain a composite video signal.

As a result, as shown in Figure 2e, the voltage generation during red imaging in the blue signal can be suppressed to A', which is an improvement over the case where the signal processing method of the present invention is not used (Figure 6C). This makes it possible to improve red color reproducibility.

Effects of the Invention As described above, in the present invention, it is possible to suppress the voltage generation during red imaging in a blue signal, and in particular, it is possible to dramatically improve color reproducibility when imaging red colors, The effects of the present invention are quite impressive.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining the signal processing method of a color solid-state imaging device in one embodiment of the present invention, and FIG.
A characteristic diagram showing the signal waveforms of each part in the signal processing circuit of the color solid-state imaging device shown in the figure, FIG. 3 is an exploded perspective view for explaining the color solid-state imaging device, and FIG. 4 is a configuration showing an example of a color separation filter. 5 is a circuit diagram for explaining the signal processing method of a conventional color solid-state imaging device, and FIG. 6 is a characteristic diagram showing signal waveforms of each part in the signal processing circuit of the color solid-state imaging device shown in FIG. It is. 27...11 children taken, 28, 33...
・Low pass filter, 3o...Band filter,
29.32...Process circuit, 31...
Detection circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 4/〆)

Claims (3)

[Claims] (1) One of the two types of color information signals obtained from the video signal output from a color solid-state imaging device having a color separation color filter is electrically processed and added to the other color information signal for color reproduction. A signal processing method for a color solid-state imaging device characterized by improving performance. (2) The signal processing method for a color solid-state imaging device according to claim 1, wherein the color elements of the color separation color filter are cyan, yellow, magenta, and green. (3) Of the two types of color information signals obtained from the video signal output from the color solid-state imaging device, the positive polarity portion of one 2R-G color information signal is electrically extracted and converted into the other 2B-G color information signal. 3. A signal processing method for a color solid-state imaging device according to claim 2, characterized in that: