JPS62133883A - Color television camera - Google Patents

Abstract

PURPOSE:To improve color reproducibility automatically by detecting the level of each color video signal obtained by photographing of a prescribed color chart and detecting difference from the ideal value of video signals of each color under this state stored beforehand, and calculating a controlling signal that makes the differential signal an optimum value. CONSTITUTION:Signals of each color R-B obtained by photographing of a prescribed color chart are gain controlled 4-6 and applied to color level detecting circuit 20-22 and level of each signal R-B is detected. Each detected level signal is inputted to the reference color signal comparator 30 of an arithmetic processing circuit 23 in which an ideal value at the time of photographing color chart is stored beforehand. Each signal level detected by the comparator 30 and reference level of stored ideal value are compared. The result of comparison is inputted to a microprocessor 31 and calculation to eliminate differential voltage of each color is performed. Controlling voltage is outputted from a matrix coefficient control voltage outputting circuit 32 to control gain controlling circuits 24-29, and color difference signals of differential amplifiers 7-9 are adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color television camera with improved color reproducibility.

(Prior art and its problems) The conventional method will be explained with reference to FIG. The R, G, and B signals, which are the outputs of the image pickup tube (not shown), are output from the preamplifier 1, respectively.
2,3. The main line video signal R1°σBr is obtained with the white balance adjusted by the gain control circuits 4 and 5°6.

The signals are also converted into color difference signals by differential amplifiers 7.8.9. These signal levels can be controlled by a fixed resistor or variable resistor 1.
It is adjusted from 0 to 15, and is superimposed on the main video signals R' and σB+ by mix circuits 16, 17, and 18 to perform one-color reproduction correction. In this way, in the conventional method, the constant of the color matrix is a fixed resistance or a variable resistance of 10 to 1
5, and optimal color reproduction is achieved only for cameras with constant spectral sensitivity. Therefore, if the 9-spectral sensitivity changes due to changes in the lens, image pickup tube, etc., optimal color reproduction cannot be obtained unless the set values of the fixed resistors or variable resistors 10 to 15 are changed. These changes were made by observing the encoder output with a vectorscope and by manual operation, so they had the disadvantage that they could not be made immediately.

(Objective) In order to eliminate these drawbacks, the present invention is designed to automatically reproduce optimal colors by capturing an image of a prescribed color chart.

(Example) An embodiment of the present invention will be described below with reference to FIG.

The main video signals R1, σB+ outputted from the preamplifier 1.2.3 and subjected to white balance adjustment by the gain control circuit 4.5.6 are sent to the differential amplifiers 7.8, 9. They are sent to color level detection circuits 20, 21, and 22, respectively. Each color signal detected by the color level detection circuits 20, 21, and 22 is as follows.

It is sent to the arithmetic processing circuit 23. Also, the color difference signal output from the differential amplifier 7.8°9 is sent to the gain control circuit 2.
The outputs of the gain control lines 24 to 29 are controlled by the control voltages inputted to the gain control lines 4 to 29 and output from the arithmetic processing circuit 23. These output color difference signals are mixed into the main video signal R' by mix circuits 16, 17, and 18.

It is superimposed on σBt and input to the video processing circuit 19.

This operation will be explained below. The color signals R, G, and B obtained by imaging a prescribed color chart are as follows.

The level of each color is read by the color level detection circuits 20, 21, and 22, and input to the arithmetic processing circuit 23. The arithmetic processing circuit 23 stores in advance the ideal color signal level at the time of imaging a prescribed color chart, and the reference color signal comparator compares the detected signal level with the stored ideal color signal. The microprocessor 31 performs optimal calculations to eliminate the voltage difference between the colors obtained through this comparison, and the IJ coefficient control voltage output circuit 32 outputs a color difference signal control voltage that allows optimal color reproduction. By inputting this control voltage to the gain control circuits 24 to 29, the color difference signals output from the differential amplifiers 7.8.9 are adjusted. This adjusted color difference signal is used as the main line video signal R'.

Optimum color reproduction is achieved by superimposing it on σB+.

Here, information on the control voltage output from the arithmetic processing circuit 23 is stored in a storage circuit (not shown) within the arithmetic processing circuit 23.

In this way, by performing direct current (DC) control over the conventional manual work of determining linear matrix constants, automatic electrical processing has become possible.

(Effects) The linear matrix method according to the present invention makes it possible to easily perform optimal color reproduction for differences in spectral sensitivity due to replacement of lenses, image pickup tubes, and the like.

[Brief explanation of drawings]

FIG. 2 is a block diagram showing the conventional system, and FIG. 1 is a block diagram showing the configuration of the present invention. 1.2, 3: Preamplifier, 4, 5, 6: Gain control circuit, 7, 8.9: Differential amplifier, 16.17.
18: Minox circuit, 19: Video processing circuit, 20.
21.22: Color signal level detection circuit, 23: Arithmetic processing circuit, 24 to 29 gain control circuit, 30: Reference color signal comparator. 31: Microprocessor, 32: Matrix coefficient system Figure 1

Claims (1)

[Claims] In a color television camera, a means for detecting the level of each color video signal obtained by imaging a prescribed color chart, a means for storing in advance the ideal value of each color video signal in this state, and a means for communicating these corresponding signals. means for comparing and detecting the respective differences, means for calculating and outputting a control signal that makes the corresponding color difference signal an optimum value from these differences, and means for controlling the corresponding color difference signal with these calculated outputs. A distinctive color television camera.