SU1288935A1 - Device for compensating background components of television signal - Google Patents

Abstract

The invention provides a reduction in the information capacities of the memory blocks of the memory channels while maintaining the specified accuracy of the compensation of the background components of the video signals. The device contains a generator of 1 compensating signals, subtraction units (BV) 2 and 3, multiplication unit 4, switches 5 and 6, background compensation error selector 7, ADC 8, memory channels 9 and 10 and control unit 14. Each of channels 9 and 10 includes a memory block 11, a DAC 12, and a low pass filter 13. The compensating signal generator 1 consists of sawtooth and parabolic line frequency generators of lines and fields and adders of these voltages with adjustable coefficients. summation. Preliminary SXoS g is made by setting the device by successively compensating for irregularities in the signals of the background of the dark and white fields (FTP, FBP). The corrected signal of the FTP is formed in BV 2. In the selector 7, it is limited to the darkest point in the visible part of the image frame. The received signal enters channel 9. The FTP error compensation signal from channel 9 arrives 2. A fully corrected FTP signal is generated at the output of the latter. . After accurate compensation of the non-uniformity of the FTP signal, the non-uniformity of the FPP signal is compensated. At the same time, the TV FBP signal, the FTP non-uniformity compensation signal from the generator 1 and the FFT non-uniformity compensation error signal are received at the BV 2. The signal from BV 2 is multiplied in block 4 multiplied by the signal from oscillator 1, which compensates for the non-uniformity of the signal in the FBP. The error signal of the FBF compensation goes to channel 10. From its output, the signal passes to BV 3, where it is subtracted from the acc. signal compensation. At the output of multiplier 4, the corrected FBP signal is generated. 3 il. i (L 1s 00 oo; o o ate

Description

The invention relates to the field of television and can be used in the construction of devices for compensating the background components of a television signal (TV) signal in various TV systems, for example, converting the contrast in color. Such devices are used, in particular, in medical X-ray television installations in the analysis of low-contrast images.

The aim of the invention is to improve the accuracy of compensation.

FIG. Figure 1 shows the electrical circuit diagram of a device for compensating the background components of a TV signal; in fig. 2 - voltage plots for compensating for the unevenness of the dark field background signal; in fig. 3 - the same, when compensating for the uneven signal of the background of the white floor.

The device for compensating the background components of the TV signal (Fig. 1) comprises a compensating signal generator 1 consisting of sawtooth and parabolic frequency generators of the lines and fields frequency and two resistive adders of these voltages with adjustable coefficients of summation, the first 2 and second 3 subtraction units, multiplication unit 4, first 5 and second 6 switches, made, for example, on a relay, a background compensation error selector 7, made, for example, on a signal limiter at the darkest point in the image field, and logo-digital converter (ADC) 8, made taking into account the required speed and resolution, the first 9 and second 10 memory channels, each of which includes series-connected memory block 11, digital-analog converter (TsAG1) 12 and low pass filter i , control unit 14.

The device works in the following way.

Initially, there are no signals at the outputs of the 13 low-pass filters of both channels 9 and 10. The device is preliminarily tuned by successively compensating for the unequalities of the signals of the backgrounds of the dark and white fields, while compensating for the irregularities of the signals of the backgrounds of the dark and white fields, respectively, the additive and multiplicative components of the background signal are compensated.

When compensating for the unevenness of the dark field background signal, the TV signal of the dark field background UTO (Fig. 2a) is supplied to the first input of the first subtraction unit 2, and the third input from the first output of the generator 1 of the compensating signals gives a signal UK compaction, (Fig. 26), consisting of a mixture of sawtooth and parabolic stresses of the frequency of lines and fields, selected

five

0

0 5

0 5

e

0

five

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so as to compensate for the unevenness of the background signal of the dark field. From the output of the first subtraction unit 2, the corrected dark background field signal Un (Fig. 2c) through the first switch 5, turned on in accordance with the external switching signal fed to its control input, goes to the input of the background compensation error selector 7, in which its restriction to the darkest point in the visible part of the image frame, determined by the signal from the third output of the control unit 14.

From the output of the selector 7, the error signal of the background compensation of the dark field LJor (Fig. 2d) is fed to the input of the ADC 8, noc / ie, which is in the N-bit binary code via the second switch 6, switched on in accordance with the external switching signal supplied at its control input, the isa input of the memory block 1 1 of the first memory channel 9 is received, in which it is stored in accordance with the enable signal received at the control input. From the output of this memory block 11, the error signal of the compensation of the dark field background is fed through the DAC 12 to the input of the low-pass filter 13, in which its smoothing is detected. From the output of the low-pass filter 13, the first channel 9 of the memorized signal of the background compensation error recovered in the analog formch (Fig. 2d) receives the first 1 subtractor 2 of the subtraction unit, the aa output of which is removed; background dark floor U - (Fig. 2e).

Compensation for the unevenness of the signal of the background of the white field is carried out after accurate compensation of the unevenness of the signal of the background of the dark field. At the same time, the first input of the first subtraction unit 2 is supplied with a TV signal of the white field background, and by a third ;; and - the second inputs are received accordingly; The compensation signal for the unevenness of the background field UKI (Fig. 26) and the signal for the compensation of the background unevenness t.: LJoT (Fig. 2e). With the release of ne; In the second block 2, the background signal of the white field Us (Fig. 3a) is fed to the first input of the multiplication unit 4, to the second input of which from the second output of the compensating signal generator 1, through the second subtraction unit 3, a compensation signal is used (Fig. 36) consisting of a mixture of sawtooth and parabolic stresses of the frequency of lines and fields, selected in such a way as to compensate for the irregularity of the white background signal. From the output of multiplication unit 4, the corrected white-field background signal Uei (Fig. Sv) through the input of the first switch 5, turned on in accordance with the external switching signal fed to its control input, goes to the input of the background compensation error selector 7.

in which it is limited by the darkest point of the visible part of the core, is represented by a signal from the third output of the control unit 14.

After that, the error signal of the compensation of the background of white zero LJo6 (Fig. 3g) (send to the input of the ADC 8, with ixoroporo as N-bit binary about 1. via the second switch b, switched on in accordance with the external switching signal supplied to its control input, it is fed to the input of the memory block 11 of the second memory channel 10, in which it is stored in accordance with the resolution signal supplied to the control f; malting input. From the output of this block 11, the error signal of compensation the white floor is fed to the input of the DAC 12, from the output of which The analog step signal is fed to the input of the low-pass filter 13, in which it is smoothed.From the output of the low-pass filter 13 of the second memory channel 10, the analog-white-error-error compensation signal of the white field goes to the second input of the second block 3, where it is subtracted from the compensation signal UKS, (fig. 36), and then goes to the second input of block 4 multiplying ikb (fig. Zd), where the corrected signal of the white background of the white field Ue is formed (fig. Ze).

After the device is tuned to its input, a real TV signal is supplied, and a corrected TV signal is taken from the output, in which the components of background distortion are additive and multiplicative.

Claims (1)

Invention Formula A device for compensating the background components of a television signal, comprising a first subtraction unit, the first input of which is the input of the device. S 0 5 0 five 0 and the output is connected to the first inputs of the first switch and multiplication unit, the output of which is an output device, serially connected analog-to-digital converter, second switch and first memory channel containing serially connected memory block whose input is the input of the first memory channel, digital - a tax converter and a low-pass filter, the output of which is the output of the first memory channel and connected to the second input of the first subtraction unit, the second memory channel, and Identical to the first channel, the memories, and the control inputs of the memory blocks of both memory channels are connected respectively to the first and second outputs of the control unit, the two inputs of which are inputs of the horizontal and frame sync pulses, respectively, and the control inputs of both switches are signal inputs switching device, characterized in that, in order to improve the accuracy of compensation, a compensating signal generator, a second subtraction unit and a background compensation error selector are introduced, the first and W The oscillator outputs of the compensating signals are connected respectively to the third input of the first subtraction unit and the first input of the second subtraction unit, the output of which is connected to the second input of the multiplication unit, the output of which is connected to the second input of the first switch, whose output is connected to the analog the digital converter, in this case, the second output of the second switch is connected via the second memory channel to the second input of the second subtraction unit, besides the selector control board The background error compensation torus is connected to the third output of the control unit, the first and second inputs of which are connected respectively to the first and second inputs of the compensation signal generator. but that but but and ig ffr S and T1 and from iloS and K.T. and: 2 Editor A. Petrov Order 7824/59 VNIIPI USSR State Committee on Inventions and Discoveries 1 13035, Moscow, Zh-35, Raushsk nab. 4/5 Production and printing company, Uzhgorod, ul. Project, 4 and Fig.Z Compiled by G. Roeatkevich Tehred I. VeresKorrektor I-Muska Circulation 659 Subscription