JPH0334279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal processing device for image signals obtained by a color television imaging device, and more particularly to a signal processing device that can perform white balance adjustment and color correction independently.

In general, television systems use NTSC (National
The system is converted into a composite color television signal compatible with a composite color television system compatible with a standard television system such as the Television System Committee system, and then transmitted, and the television signal is received by a television receiver to display the image. It's playing.
In order to reproduce faithful images in such television systems, it is necessary to adjust the white balance of the three primary color signals obtained by the imaging device, and perform gamma correction on the imaging side, which reversely corrects the gamma characteristics of the image receiving side. It is necessary to perform various signal processing on the video signal on the imaging side, such as color temperature correction for the color temperature of illumination at the time of imaging.

The various signal processing described above has conventionally been performed by controlling the response characteristics of preamplifiers, process amplifiers, etc. installed in the imaging device, and white balance adjustment and color correction are related to each other. Since the signal processing is performed based on the image quality, the degree of freedom in color correction is particularly limited, and it is not possible to perform sufficient signal processing in accordance with actual imaging conditions.

The present invention uses a data table in which white balance adjustment data is written in advance in a first memory, and a data table in which color correction data is written in advance in a second memory. It is an object of the present invention to provide a signal processing device with a novel configuration in which balance adjustment and color correction can be performed independently, thereby increasing the degree of freedom in color correction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing one embodiment.

In the embodiment shown in FIG. 1, a color imaging signal obtained by a color imaging section (not shown) is digitized by an analog-to-digital (A/D) converter 1, and then a color signal is sent to a bandpass filter 11. C
At the same time, the color signal C is subtracted and synthesized in the signal adder 2 to separate the luminance signal Y, and correction data ΔCP formed based on the color signal C and the luminance signal Y is output. A side signal adder 8 performs addition and synthesis to perform correction, and output from an output terminal 10 via a digital/analog D/A converter 9.

The color signal C separated by the bandpass filter 11 is separated into a U color signal and a V color signal by a signal separation circuit 13. The above U color signal is the first
The blue primary color difference B−Y
converted into a signal. Further, the V color signal is passed through a second frequency interpolation filter 16 to a second multiplier 17.
The signal is supplied to the multiplier 17 and converted into a red primary color difference RY signal. The Y signal, B-Y signal and R-Y signal are supplied to the first matrix circuit 18, and from the matrix circuit 18 the three primary colors R, G, B
Get a signal. The R signal, G signal, and B signal obtained by the matrix circuit 18 are sent to a first memory 20 in which a color correction data table is written and a second memory 30 in which a white balance adjustment data table is written. is used as each read address signal. Further, the Y signal is used as a read address signal for the color correction data table written in the first memory 20.

Here, each of the memories 20 and 30 is composed of, for example, a random access memory, and the three primary colors R calculated by the microprocessor 40,
Various correction data regarding the G, B signals and the luminance Y signal are written in advance.

The three primary color correction signals △R, △G, △B read out from the first memory 20 are converted into color difference forming signals in the second matrix circuit 21 and then sent to the third and fourth multipliers 22 and 23. After weighting, the signal synthesizer 24 converts the signal into a color correction signal ΔC. This color correction signal ΔC is added and synthesized with the luminance correction signal ΔY read from the first memory 20 in a signal adder 25, and is supplied to the signal adder 8 on the output side as correction data ΔCP.

Further, the white balance adjustment signals △Rw, △ of the three primary color signals read out from the second memory 30 are
Gw and △Bw are converted into color difference formats △(B-Y)w and △(RY)w by a matrix circuit 31, and each signal adder 32, 33 for white balance detection
are weighted by multipliers 34 and 35 and converted into white balance adjustment signals △Uw and △Vw corresponding to the U color signal and V color signal. The signal is supplied to a signal combiner 24. The signal adders 32 and 33 for detecting the white signal add adjustment signals Δ(B-Y)w, Δ(RY) to the color difference B-Y and RY signals formed from the input imaging signal. )w are added and combined, and a signal is supplied to the white signal detection circuit 36. This white signal detection circuit 36 always determines the presence or absence of a white signal with respect to the input imaging signal, and when the white signal is present, the signal selection circuit 36
8 to supply white balance adjustment signals ΔUw and ΔVw to the signal synthesizer 24.

Here, for example, in the case of a standard color television signal of the NTSC system, in the white signal detection circuit 36, R-Y+0.7△Rw-0.11B=0...First equation B-Y-0.3△Rw+0.89B= 0 . . . The white signal can be determined by determining whether or not the first and second equations, which are the second equation, are simultaneously satisfied. Also, instead of the first and second equations above, (RY)-(B-Y)+△Rw-△Bw=0
. . . Even if it is determined whether or not the third equation (3rd equation) is satisfied, a white signal can be detected.

In the embodiment configured as described above, the first memory 2
The signal selection circuit 38 selects the color correction processing based on the color correction data table written in the second memory 30 and the white balance adjustment processing written in the second memory 30, and independently inputs the input imaging signal. It can be applied to The operation of the signal selection circuit 38 is controlled by the white signal detection circuit 36.
When the input imaging signal is a white signal, that is, when white balance adjustment is required, the state is automatically switched to the white balance adjustment state, so that any color correction can be performed while maintaining white balance.

As is clear from the description of the embodiments above, according to the present invention, a first memory in which a color correction data table is written, and a second memory in which a white balance adjustment data table is written. , a white signal detection circuit for detecting whether or not the input imaging signal corrected based on white balance adjustment data read from the second memory as a signal level of the input imaging signal is a white signal; The signal level of the imaging signal is used as the address in the first
The color correction data read from the memory of
a signal selection circuit that receives white balance adjustment data read from the memory of the circuit and outputs one of the color correction data and the white balance adjustment data based on the output signal of the white signal detection circuit; an adder that adds an output signal of the circuit to the input imaging signal, and the signal selection circuit adds the white balance adjustment data while the input imaging signal corrected based on the white balance adjustment data is a white signal. , and an output video signal is obtained from the adder, so that when the input imaging signal is a white signal, that is, when white balance adjustment is required, the output video signal is automatically adjusted. The camera automatically switches to the white balance adjustment state when the input imaging signal is a signal other than a white signal, and automatically switches to the color correction state, making it possible to perform color correction processing and white balance adjustment independently. , color correction can be performed with a high degree of freedom, and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a signal processing circuit according to the present invention. 1...A/D converter, 8, 12, 25, 32,
33...Signal adder, 9...D/A converter, 10
...Signal output terminal, 20, 30...Memory, 36
...White signal detection circuit.

Claims (1)

[Claims] 1. A first memory in which a color correction data table is written, a second memory in which a white balance adjustment data table is written, and reading from the second memory using the signal level of the input imaging signal as an address. a white signal detection circuit for detecting whether or not the input imaging signal corrected based on the white balance adjustment data to be corrected is a white signal; and a white signal detection circuit for reading out the signal level of the input imaging signal from the first memory as an address. The color correction data read out from the second memory and the white balance adjustment data read from the second memory are input, and one of the color correction data and the white balance adjustment data is output based on the output signal of the white signal detection circuit. and an adder that adds an output signal of the signal selection circuit to the input imaging signal, and the signal selection circuit adds the input imaging signal corrected based on the white balance adjustment data to white. An imaging signal processing circuit characterized in that the circuit is configured to output the white balance adjustment data while the signal is being output, and to obtain an output video signal from the adder.