JPS5820094A - Video processing circuit - Google Patents

Abstract

PURPOSE:To simplify the constitution of a color coder and a gamma compensation/ matrix arithmetic part as well as to increase the color reproducibility and to miniaturize a video processing circuit, by giving the prescribed gamma compensation to each address contents of a memory and then storing the ideal value multiplied by a prescribed coefficient. CONSTITUTION:Both the luminance and chrominance signals I and Q of the primary color video signal component are fed to the primary video signal input terminals 1-n. The memories M1-M3 are connected to the terminals 1-n as the exclusive storage circuits. The gamma compensation is given to the primary color signal which is digitized by the memory M1, and the digital value of the primary color video signal of the color difference signal is delivered by the value multiplied 1 by the prescribed value. Then the gamma compensation is given to the primary color video signal which is turned into the digital value by the memory M2, and the digital value of the primary color video signal of the I color difference signal multiplied by the prescribed value is delivered. At the same time, the digital value of the primary color video signal of the Q color difference signal is delivered in the same way by the memory M3. Thus the constitution is simplified for a color coder and a gamma compensation/matrix arithmetic part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image 4611 circuit that performs gamma correction on a digitized primary color image signal and simultaneously obtains a luminance signal, an X color difference signal and a q color difference signal.

Conventionally used color cameras use analog signal processing to process primary color signals (for example, red, edge,
After performing gamma correction on the lower front edge (R, G, B) in a well-known manner, they are introduced into a matrix circuit of a color camera to synthesize luminance signals and color difference signals.

In such an analog processing system C=, the drift of the gamma correction circuit and matrix circuit.

Errors caused by changes in the trigger time cannot be ignored.

It was necessary to revisit it through daily and periodic inspections.

For this reason, in recent years video signals have been converted to digital.

A method has been proposed that performs space calculations. However, the currently proposed method is to perform gamma correction on each digitalized primary color video signal, and then perform matrix operations by shifting, adding and subtracting the digital signals.

For example, the matrix operation to obtain the luminance signal is as follows α)
It is done by a formula.

my-0.30g1+0.591o+0.00mm・6
．． α) Here * ``N o '' G t '' l and 1 are the voltage levels of R, G, B and luminance signals, respectively.

α from the digitalized R, G, and H primary color video signals
), the calculation example proposed as an example of a method using the aforementioned left circuit and addition/subtraction is 0.30,2 +2 −0.3125 −−−−−−
(2) o, 5o=z +2 -0.5625...
・River (3) 0, 11.2 -0.125 -----
−−−−−−−−−− (4), and this (2) −
This is a method using left and addition of digital signals (ie, binary numbers) as shown in equation (4).

Although the sum of the coefficients shown in formulas (4) to (4) is maintained at 1, there is a considerable error from the coefficients of formula (1) defined in the NT/8C system. That is, the coefficient of R is about 4%, the coefficient of G is about -4.7%, and the coefficient of B is about 13.6%.

This kind of thing also occurs when combining the I and Q color difference signals, and it is easy to imagine that the color reproduction error on the cathode ray tube of the receiver due to these errors will be larger than that of the conventional analog system (the analog system is matrices).・Designed with the goal of keeping the error in the Kux constant to around 1% or less).

Increasing the number of lifts and addition/subtraction in order to reduce these errors greatly reduces the shape of the color camera, and requiring a separate digital gamma correction circuit worsens these conditions (the shape of the color camera). I end up.

This invention has been made to eliminate the above-mentioned drawbacks of the conventional technology, and includes an output for combining a luminance signal and I, Q color difference signals at the same time as gamma correction in digitalized primary color video signal processing 42. The object of the present invention is to provide an image processing circuit that can be used to make a color camera circuit more compact, more compact, and lower in power consumption.

Hereinafter, one embodiment of the video processing circuit of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a circuit for obtaining thickness color image signal components of a luminance signal and I, Q color difference signals in one embodiment.

1~+m in this figure 1 is 1 pin)! This is a digitized R primary color video signal input terminal. This R[input line number connected to color video signal input terminals 1 to 11== is inputted as an address selection signal of read-only storage circuits M1 to Ml (hereinafter referred to as memory). For example, the contents of each address in the memory M1 are the output characteristics obtained when gamma correction is applied to the video level of the digitized R primary color video signal (the broken summary in Figure 2 is the gamma correction characteristic curve). (The solid line A is the characteristic when there is no Gamma correction and r-1. The r value of the dotted line is about 0.45. This is the same as the analog gamma correction.)
The output ratio O, a The binary digital value multiplied by O is stored.

That is, the contents of memory M1 are digitized R
Gamma correction is applied to the primary color video signal.

The value obtained by further multiplying by 0.30 becomes the digital value of the component of the luminance signal due to the R primary color video signal. This digital value is 1171. It can be obtained as IRYI... (Since this output can be obtained as long as the input has a coefficient smaller than 1, it does not matter if there are fewer than a bits).

Note that CLK in FIG. 1 is a control input that controls reading of the contents of the memos 9M1 to M1.

Similarly, gamma correction is applied to the gray primary color video signal digitized by the memory M2.

Another 0.601'l! By doing so! A value is obtained in the digital component of the R primary color video signal of the color difference signal. This digit has a value of 1111. Ml! ! , which is obtained as...

The I and Q color difference signals are defined by the following formula (6). here! The coefficient of k for color difference signal synthesis is 0.6
0, which is exactly twice that of the luminance signal synthesis (0, 30), so 1111. III! By shifting F by 1 bit, 1ilY1. II□300. Needless to say, you can get it.

I t-0,601m-0,281e-0,321m
ms++*Ql)I Q-0,21111-0,521
o+0.311 B. Participation (6) Memory Ml, same as Ml, R of q color difference signal after gamma correction by memory M1
A digital value of the component based on the primary color signal is obtained.

The R primary color video signal has been described above.

It is clear that the same thing is possible for G and B as well. In other words, if the circuit shown in Fig. 1 is applied to the G and B layer color video signals, the gamma-corrected and necessary coefficients [(1), @), m
) It is possible to obtain a digital value output multiplied by each coefficient ) of the equation.

That is, FIG. 3 is a block diagram of a circuit for synthesizing a luminance signal and a color difference signal according to the present invention.
In the figure, 10, 11° and 12 are digitized beast, G, and B primary color signal input terminals, respectively.
Each is connected to the memory IJ-11. These memories 11 to 11 are memories like memos 9MJ to MJ in Figure 1, respectively, and their outputs are multiplied by the coefficients of equations α), (5), and (8) after 1 nigamma correction as described above. This becomes the output.

The outputs of these memories 11 to 15 are sent to the luminance signal synthesis circuit 1.
6.1 Color difference signal synthesis circuit JF, Q color difference signal synthesis circuit 11
The luminance signal II and ! are sent to the luminance signal II and ! It is possible to obtain the digital value output of the color difference signal 2o%q color difference signal 11.

As is clear from the above, the contents of each address in the memory are after predetermined gamma correction (approximately 0.45) (IL(5), (
The ideal value multiplied by the coefficient of the @ expression can be stored.

On the other hand, since the number of bits of a digital value is finite, the actual error that occurs is ±1/Ll! It becomes B. That is, gamma correction and color coder matrix calculation can be performed at the same time with a high precision of approximately ±0.2% for 8 bits and ±0.0OS% for 10 bits.

This simplifies the configuration of the color coder matrix calculation unit that performs gamma correction from multiple digital primary color video signals, and improves color reproducibility due to improved accuracy.In addition, it reduces circuit size, reduces power consumption, and improves productivity. It is possible to reduce costs and improve reliability.

In addition, the same method is used for primary color video signals other than ml, G, and B, and R-
Y, B-Y etc! , it goes without saying that it is also effective when using other than Q.

As described above, according to the video processing circuit of the present invention, in a color television camera, two people simultaneously perform gamma correction on each read-only note C using a digitized primary color video signal as an address selection signal. Luminance signal, I color difference signal, Q! respectively. ! 1! Luminance signal component of each digital value, multiplied by a coefficient to obtain the signal! Since the color difference signal component and the Q color difference signal component are output, gamma correction and color coder matrix calculation can be performed simultaneously with high precision.

Along with this, Gashima correction, color coder and
It is possible to improve color reproducibility and obtain high reliability due to the simplification and high precision of the configuration of the lux calculation unit, and also to achieve miniaturization and low power consumption.

[Brief explanation of the drawing]

The first @I is a luminance signal in the video processing circuit of the present invention,
■A block diagram of a circuit that obtains primary color video signal components from color difference signals and Q color difference signals.
When gamma correction is applied to the video level of the primary color signal
：O3 showing the obtained gamut characteristics, FIG.
FIG. 2 is a block diagram for synthesizing six color difference signals. J-vH...R primary color signal input terminal, M1 to Ml,
11 to 15...Memory, 1#...Luminance signal synthesis circuit, JP...I color difference signal synthesis circuit, 1#...Q color difference signal synthesis circuit. Applicant's agent Patent attorney Suzu Ushiki Hiko Shima, Commissioner of the Patent Office 1) Haruki Tono1. Indication of the case Japanese Patent Application No. 118738/1982, Name of the invention Video processing circuit 3, Person making the amendment Relationship to the case Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 5, Voluntary amendment 76, Details of the amendment rEY on page 3, line 8 of the book = 0.3OtR10.59EI+0.00E (
IIJ as “Ey=0.30M &+0.59E excellent+0.
11E... (Corrected as IIJ.

Claims (1)

[Claims] The value 1 is the value 1 obtained by inputting the digitized primary color video signal tube address selection signal into a predetermined bit in a color television camera and performing gamma correction on this digitized primary color video signal; the coefficient for obtaining the luminance signal component. a first read-only storage means for outputting the luminance signal component of the digital value after multiplication; and gamma correction of the digitized primary color video signal by inputting the digitized primary color video signal as an address selection signal. a second read-only storage means for outputting a digital one-color difference signal by multiplying the value by a coefficient for obtaining a one-color difference signal; and a second read-only storage means for outputting a digital one-color difference signal; A video processing circuit comprising third read-only storage means for outputting a value obtained by performing gamma correction on the primary color video signal to obtain a Q color difference signal.