SU1603537A1 - Method and apparatus for color correction of tv camera - Google Patents

Abstract

The invention relates to television. The purpose of the invention is to improve color accuracy. To implement the color correction method, a device is used comprising a dispersion prism 1, a video signal sensor 2, a color correction matrix 3, selectors 4 and 9, a subtraction unit 5, an absolute value detector 6, an integrator 7, an extreme regulator 8, r-10 curve shape signals mixing unit 11 of the memory of the coefficients of matrixing and the synchronous generator 12. With an inaccurate color correction in the device there are differences in the compared signals from the selectors 4 and 9 to the subtractor 5. With the help of detector 6 and integrator 7 tyvaets signal used by regulator 8 as an estimate of the accuracy of color correction. The controller 8 searches for a color correction control signal that minimizes the amplitude of the signal arriving at its information input. In this case, an extremum search algorithm is used by the method of quadratic extrapolation. Given il. perform matrix 3, the controller 8 and the synchronous generator 12. 2 sec. f-ly. 4 il.

Description

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The invention relates to television and can be used in broadcast and applied television as part of television systems for automatically correcting image distortion with feedback, operating in real time.

The purpose of the invention is to improve the accuracy of color correction.

FIG. 1 shows a block diagram of a device that implements the method of color correction of a television camera; in fig. 2 is a block diagram of the color correction matrix i in FIG. 3 is a block diagram of an extremal regulator; in FIG. 4 is a block diagram of a synchronous generator.

The device contains dispersion prism 1, video signal sensor 2, color-correcting matrix 3, first selector 4, subtraction unit 5, absolute value detector 6, integrator 7, extremal regulator 8, second selector 9, bias waveform generator 10, memory block 11 These coefficients matrixov sh and sync generator 12.

Color correction matrix 3 consists of a block of 13 digital attenuators, the first 14, the second 15 and the third 16 adders.

The extreme controller contains a microprocessor 17, an operating memory unit 18, a permanent memory unit (PPU) 19, an input / output unit 20, an analog-to-digital converter 21, a decoder 22, and registers 23-31.

The clock generator consists of a multi-bit counter 32, a differentiating circuit 33, a delay line 34 and a multivibrator 35.

The method is carried out as follows.

The light flux from the white light source is converted at the output of the dispersion prism 1 into the spectral decomposition pattern of this flux. The resulting picture is placed in the focal plane of the lens of the video signal sensor 2, and is positioned so that the change in the spectral components in the picture occurs in the direction of the frame sweep. The video signal sensor 2 forms three color-separated image signals, the instantaneous amplitude values of which are proportional to

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the intensity of the spectral components of the luminous flux, reaching up to the photoelectric converter of the corresponding color separation channel. Since the frequency of the spectrum of the light flux at the output of the dispersive prism 1 varies linearly, the video signal at the output of sensor 2 of the video signal with its shape repeats the shape of the spectral characteristic of the color separation channel in which these signals are formed. The color correction matrix 3 performs the weight summation of the three color-separated image signals. For this, a block of 13 digital attenuators from three color-separated image signals forms nine electrical signals (three from each color-separated channel signal), the amplitude and phase of which are determined by a digital control input, the input of which receives a digital code on a seventy-two-bit bus organized as Nine (by the number of attenuators in block 13 digital attenuators) single-byte buses. One-byte digital control signal. for each attenuator in the range of 0.. .127 .. .255, have a transmission coefficient for this attenuator -1 ... 0 ... + 1. At the output of the first adder 14, the sum of the electrical signals of the first color-separated channel and the suspension of the signals of the three color-separated channels, which together form a color-corrected color-separated image signal of the first channel, are obtained. Similarly, at the outputs of the second 15 and third 16 adders, the color corrected image signals, respectively, of the second color-separated channel and the third one are found. If the control input of the block 13 receives nine identical digital control signals, then the outputs of the block 13 of the digital attenuator have no signals, and the color separation signals at the outputs of the color correction matrix 3 repeat the signals at its similar inputs, i.e. no color correction. Synchronized sensor 2 video signals are received. Line and frame sync pulses, which synchronize the operation of the generator 10 with the television scan. In this case, the frame sync pulses determine the initial phase of the gene operation.

Rattor 10, and the horizontal sync pulses the rate at which the amplitude of the generated signals changes in the direction of vertical sweep. The first 4 and second 9 selectors switch one of the three analog signals that are applied to their inputs in such a way that the corresponding color signal of the color selector image passed through the first selector 4, the corresponding generator signal 10, which determines the shape of the mixing curve of the channel, is switched. switching determines the setup time of one color separation channel and corresponds to one hundred and eighty frame periods. Since the switching period determines the period of changing the address digital code at the address inputs of the first D and second 9 selectors, the code for which comes from the first output of the synchronous generator 12, which is formed by the first and second outputs of the multi-bit counter 32, the conversion factor of the latter should be three hundred and sixty This allows to obtain the necessary time ratios when the sync generator receives 12 HR sync pulses. The first and second inputs of the subtraction unit 5 receive analog signals, with the first input the color-corrected image signal, and the second the signal of the mixing curve form. If color correction made it possible to completely eliminate color distortions, then the image signal obtained by scanning the spectral image from white would repeat the view of the mixing curve of this color separation channel, and therefore when comparing it with the signal coming from the generator 10 waveforms mixing curves, their full identity would be determined, and the signal at the output of subtraction unit 5 would be zero. When there is an inaccurate color correction, differences B appear comparing the # 1 signals, the instantaneous value of the amplitude of the difference signal shows the difference between the actual mixing curve and the calculated one at the point in question. The absolute value detector 6 converts a bipolar difference signal into a unipolar signal, mirroring one of the polarities relative to zero

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level The integrator 7 accumulates a unipolar signal acting at its input, forming a potential by the end of the accumulation interval, and the slice of which shows the total (over the entire raster area) discrepancy of the real and ideal mixing curves. This potential is used by the extreme regulator 8 as an estimate of the accuracy of color correction. The accumulation time of the integrator 7 is determined by the period of the pulse arriving at the input 15 of the reset of the integrator 7. This pulse

forms synchro sender 12 of the frame. first sync pulse arriving at its sync input. The frame sync pulse is delayed by the delay line M 34 for the time required to perform analog-digital conversion, and is formed on the leading edge of the delayed pulse by the multivibrator 35, resetting 25 the integrator 7. The extreme regulator 8 searches for a color correction control signal that minimizes the amplitude of the signal arriving at its first information entry. In the specific case, an extremum search algorithm is used by the method of quadratic extrapolation. For this purpose, PPP 19 records the work program of the extremal controller 5L of the torus 8. The program contains three identical parts, which determine the sequential setting of three color-separated channels of a television camera. The synchronization of the nporpaMhbi execution with the commutation of selectors 4 and 9 is performed using pulses from the third and fourth outputs of the multi-bit counter 32 to the first and second microprocessor interrupt enable inputs 17. One of these pulses occurs at the moment the control code changes address obtained at the first output of the synchronous generator 12, and determines the transition of the tuning program to the next split color channel, another impulse occurs at the moment of overflow of the multi-bit counter 32, and this serves as a condition the beginning of the program on the first tstedelennom.- channel.

Claims (1)

Formula invented and I..The method of color correction of a television camera, 1H1, 1H1 | iigs in the control wire 2 Sync block Fig.Z