SU1672591A1 - Device for generating color image for systems using line- sequential method to transmit images - Google Patents

Abstract

The invention relates to television. The purpose of the invention is to improve the quality of the television image by reducing cross-sectional distortion. The device for forming a color image signal contains two blocks 1 and 2 delays for the duration of a television (TV) line, a receiver synchronization signal selector 3, a synchronization unit 4, a control unit 5, two switches 6 and 10, a basic color signal generator 7, two amplitude limiters 8 and 9, an adder 11, three gamma corrector 12-14 and a coding block 15. The goal is achieved by the fact that the adder 11 and the second switch 10 perform the summation of the missing components of the video signals from the white line and suppress the modulation from the color-coding its light filter in the entire color range of the television system. The introduction of limiters 8 and 9 reduces the level of moire interference. The limiters 8 and 9 and the coding unit 15 of the PAL or SECAM system make it possible to reduce the visibility of the parasitic coloring of lines on horizontal transitions. 4 il.

Description

The invention relates to television, in particular, to video signal processing devices of color television telecommunication systems, video recording and application television.

The purpose of the invention is to improve the quality of the television image by reducing cross-sectional distortion.

Fig. 1 shows a structural electrical circuit of a device for forming a color image signal; figure 2 - diagrams of distortions at the input and output of the first switch; Fig. 3 shows voltage plots illustrating the operation of the adder and the second switch; Fig.4 transient response of the device during the formation of a black and white transition.

The device for forming a color image signal contains the first block 1 of the delay for the length of the television (TV) line, the second block 2 of the delay for the length of the TV row, the selector 3 of the receiver synchronization signal, the block 4 of the synchronization, the block 5 of control, the first switch 6, the imager 7 Signals of primary colors , the first amplitude limiter 8, the second amplitude limiter 9, the second switch 10, the adder 11, the first, second and third gamma correctors 12-14 and the coding unit 15.

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The device for forming a color image signal operates as follows.

From a video signal sensor (not shown) consisting of a TV camera with a light converter - a signal with a raster color-coding light filter of the structure white (W) - yellow, (Ye) - blue (Su), the video signal goes to the input of a color image forming device . On the first, second and third inputs of the first switch 6 there are three video signals OH, 1H and 2H (see Fig. 2a), coming directly from the input of a decoder (OH), from the output of the first delay unit 1 for the duration of the TV line (1H) and from the output of the second block 2 delays for the duration of the TV line (2H), i.e. The inputs of the first switch contain all three video signals corresponding to the coding triad of the light filter.

The switch 6 in the row with the number N is the output of the white channel W connects to the video source OH, in the row with the number N + 1 - with the output 1H of the first block 1 delay, and in the row with the number N + 2 - with the output 2H the second block 2 delays. On line number N + 3, output W is again connected to the output of the video signal source OH and the process is repeated. Thus, at the output W of the switch 6, the video signal of the white line with the number N - Wn will be repeated three times, and then the video signal of the white line with the number will be there: L / R + 3. Similarly, the separation of the video signals of the blue and yellow colors of the color-coding light filter, but the moments of change of the video signals will be on the lines with the number N + 1 and N + 2, i.e. shifted by 64 and 128 μs, respectively (see fig.2bv).

The signals of red (R) and blue (B) primary colors are formed from the video signals of white, blue and yellow colors by subtracting in the imaging unit 7 signals of primary colors in accordance with the equation

GK,

-K2 ± Кз К5-Кб

W Su Ye

where the coefficients of the matrix color correction Kz and Kb are much smaller in absolute value than Ki, K2, K $, Kb and serve to reduce color distortions in the system. The formation of red and blue signals by subtraction uses the fact that the signals of two adjacent lines are rather strongly correlated. The reduced vertical clarity of the color image is allowed by the color vision features, but in a bright signal it must be high to maintain good image quality.

For this purpose, a pseudo-luminous OH signal from the video signal sensor is used, where the spectral sensitivity characteristic of the video signal sensor with a white LED color filter is W

0 is formed in accordance with the visibility curve of the Y MKO-31 with a rise in the blue region of the spectrum to increase the sensitivity in the blue channel. Spectral characteristics of blue and yellow stripes

5 color-coding light filter obtained from white (pseudo-bright) by cutting off the red and blue spectral components. Thus, the modulation of a video signal by the structure of a color-coding filter of light (cross-color distortion - brightness) is caused by the absence of video signals corresponding to the red and blue ranges of the emission spectrum in the blue and yellow lines (see

5 of FIG. 3a) The adder 11 and the second switch 10 of the e-channel channel sum the missing components of the video signals from the white line (see FIG. 36) and suppress the modulation from the color-adjusting light filter in the entire color range (see FIG. Sv)

Consider a transient response in the vertical direction for a black and white transition. On figa presented

5 transient characteristics for the case of formation of a luminous signal by summing the signals R and B without amplitude limiters when the black and white transition falls on the yellow-white line

0 (solid), white - blue line (dashed lines) and blue - yellow line (dash-dotted lines). On fig.cha shows that the transition characteristic has significant positive and negative

5 spikes, which leads to strong moire distortions of scenes such as horizontal stroke worlds. The large emission amplitude at the transient response is due to the fact that the signals R and

0 V also have an emission amplitude of ± 300 and ± 900%, their appearance is caused by the formation of these signals by subtraction, and the moments of change of the two original signals are shifted relative to each other by

5, the length of the string such that when one of them has changed its amplitude, the second still repeats the signal of the previous row (see Fig. 4b). The introduction of the first and second amplitude limiters 8 and 9 of channels R and B allows these emissions to be limited to 100% amplitude, since the amplitude of the video signal does not carry useful information. Fig. 4b shows the transient response of the luminance channel with amplitude limiters 8 and 9 in the red and blue channels, which shows that the distortion of the transient response has been greatly reduced.

The summed video signal of brightness Y, red R, and blue B colors is fed to the first, second, and third gamma correctors 12-14, where they are normalized to obtain white balance on the TV monitor screen and gamma correction to compensate for the nonlinearity of the kinescope modulation characteristic.

From the output of gamma correctors, video signals are fed to the inputs of the coding block 15. Signals for controlling the coding block Are formed by the synchronization block 4. The use of a coding block using PAL or SECAM systems allows to additionally reduce cross-lighting brightness - chromaticity distortions. The full video signal generated by the encoder is fed to the input of a color video monitoring unit (not shown).

Similarly, the decoder operates as part of television systems with color-coding light filters of other structures consisting of a combination of green (G) and its complementary colors: white (W), yellow (Ye), blue Su), for example W-G-Cy. W-G-Ye, etc.

Thus, the proposed device-: your allows you to reduce cross-distortions of brightness - chromaticity and chromaticity - brightness associated with the chosen: color-coding tool. The summation method for the missing components into the RC signal allows alignment of the amplitudes of video signals in the full range of colors of the television system, and the introduction of limiters before the adder reduces the level of moirés. Amplitude limiters in cana-iax primary colors and the use of a coder device of the PAL or SECAM 1 systemEyut it is possible to reduce the visibility of the parasitic coloring of rows on horizontal (transitions, which indicates a decrease in the brightness distortion - chromaticity.

Claims (1)

Invention Formula The device for forming a color image signal for systems with line-to-sequential method of transmitting images contains the first block of delay for the duration of a television (TV) line, the input of which is connected to the first input of the first switch and is 10 input device for forming a color image signal, the second delay unit for the duration of the TV line, the input of which is connected to the second input of the first switch and the output of the first power supply unit for the duration of the TV line, and the output connected to the third input of the first switch, receiver selector signal selector whose input is connected to the first input of the first switch, and output 20 to the input of the synchronization unit, the first output of which is connected to the input of the control unit, the first output of which is connected to the fourth input m first switch, whose output is connected to the input formi25 rovatel primary color signals and the first, second and third gamma correctors, characterized in that, in order to reduce crosstalk in the formation of the primary colors are introduced 30, the first and second amplitude limiters, the second switch, the adder and the coding block, the output of the adder being connected via the first gamma corrector to the first input of the coding block, the output of sig35 and the red component primary color driver through the first amplitude limiter and the second gamma corrector is connected to the second input of the coding block, the signal output The 40th blue component of the primary color signal generator is connected via the second amplitude limiter and the third gamma corrector is connected to the third input of the coding block, the first input is the sum of 45 tori connected to the first input of the first switch, the second input of the adder is connected to the second switch the output of the control unit, and the second and third inputs - to 50 outputs, respectively, of the first and second amplitude limiters, the fourth input of the coding block is connected to the second output of the synchronization block. J I / t-