SU860345A1 - Method and device for forming tv signal envelope correction signal - Google Patents

Description

by corresponding sections, this causes a spatial shift of the correction signal relative to the image being corrected. In addition, the accuracy of the correction is significantly degraded in the presence of electrical noise and glare of image details.

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

In order to achieve the goal in the proposed method, when forming a sample for each section of the next field of the corrected TV image, the auxiliary signal is subtracted from the TV signal, the level characterized by the specified excess probability is measured in the received signal, and the auxiliary signal is formed by matching the corresponding recalled sample from the signal received as a result of repeated filtering.

A unit for shaping the readout signal is inserted into the device for implementing the proposed method, the first input of the KOTOjporo is connected to the output of the memory unit, the second input is connected to the output of the gating and smoothing unit, and the output is connected to the third input of the sample size calculation unit.

FIG. 1 shows a structural electrical circuit of a device for generating a TV signal envelope correction signal; in fig. 2 version of the distribution of shtsy TV images within the standard TV solution; in fig. 3 - voltage plots illustrating the errors in the formation of the correction signal; in fig. 4 - voltage plots illustrating the reduction in error when using ojc4eTHbix signals.

The device for generating the envelope correction signal TB of the signal contains N formers of 1 samples, each of which belongs to one section of the image being corrected and consists of a block 2 for calculating the sample size, a block 3 for generating the reference signal and a block 4 for memory, block 5 for synchronization, block 6 for gating and smoothing. The combined inputs of the driver 1 and the output of block 6 are the input and output of the device, respectively.

The device works as follows.

The TV signal is fed to the input of the device and is distributed between the formers of the 1 samples, in which the blocks 2 alternately calculate the values of the samples. The order of their action is determined by the sequence of scanning corresponding to the image areas and is determined by the synchronization unit 5. The nalimer, when dividing the image of a 12 plots (Fig. 2), while scanning the upper part of the field, alternately calculates the samples for

Parts 7–10, then, during the scan of the middle part of the field, samples are computed for sections 11–14, and so on.

Simultaneously with the calculation,

generating an envelope correction signal using samples read from memory blocks 4 (Fig. 1), which were calculated during the scanning of the preceding TV image field. These samples are read and fed into a gating and smoothing unit 6, the output of which produces an envelope correction signal. is he

serves to correct the TV signal and, in addition, is used in the formation of 5 counting signals in blocks 3 by subtracting from it the re-memorized sample stored in the corresponding memory block 4.

Block 2 measures in the input video signal a level exceeded with a given probability in the scan interval of the corresponding image area, and the measurement is made relative to the reference signal generated by block 3. Such a measurement can be performed by subtracting the reference signal from the video signal and producing double gradation quantization of the difference signal by the level obtained by the nonlinear integrator of the quantized signal. The same level determines the computed sampling value transmitted for storage to memory unit 4 upon completion of the calculation process.

Claims (2)

Typical calculation errors occur when the video signal levels from different parts of the image are significantly different, for example, as shown in FIG. This is a cross section of the vertical level distribution. Assume that the left portion in FIG. The corresponding section 8 in FIG. 2, the center section 12, and the right section 16. The calculated sampling level (in FIG. 3A is made with a solid horizontal line) in the left section is 50% of the nominal, in the center section it is equal to nominal, and in the right section it is equal to nominal. determined only by a single ejection near the left border of the right portion. Because of this, the correction signal (Fig. 36) does not reflect the decrease in the contrast of the details in the image section 16 (Fig. 2) and does not allow the required contrasting to be performed. As a result of the correction, the contrast of the details in the image section 8 approaches the nominal, in section 12 it exceeds the nominal value due to the smoothing of the samples at. the formation of the correction signal, and in section 6 remains, as before, 1shzkim. 5 Simultaneously with the correction, a sampling signal (Fig. 4a) is formed by subtracting the sample levels (Fig. 3a) from the envelope correction signal (Fig. 36). The correction introduced by the reference signal takes the sampling levels dp of the left portion recorded in the next image field and overestimates the sampling level for the central portion, as a result of which the envelope correction signal (Fig. 46) and the readout signal (Fig. 4c) are generated. FIG. 4g shows the correction signal. In the third field, the correction process covers the right area 16, and the effect of the reference signal is aimed at reducing the sample size. According to the results of the calculation of the sample values, the envelope correction signal (Fig. 4e) and the readout signal (Fig. 4e) are formed in the third field, reflecting more accurately the nature of the envelope of the real video signal than their original approximations (Fig. 36 and 4a). The achieved increase in the accuracy of the formation makes it possible to carry out contrasting not only on the left, but also on the right part of the image (Fig. 4g). Consequently, the use of reference signals helps to reduce the formation of formation caused by dividing the image into a small number of large areas. Calculating the sample size as a level characterized by a predetermined probability exceeding contributes to the reduction of formation errors due to impulse noise and the glare of image details. and the error is determined only by the duration of the interference. Thus, the proposed method and device can significantly improve the accuracy of forming the correction signal of the envelope of a TV signal. The effect of the application of the invention is expressed in an increase in the degree of contrast of the images with an uneven distribution of the contrast of the details, as well as in an increase in the processing accuracy of the impulse noise and in the glare of the details of the image. Claim 1. Method of forming the envelope correction signal of a television signal, based on dividing the corrected television image into sections, generating and storing samples of the correction signal dp of each section of the next field of the corrected television image, reading the sequence of samples ahead of the frame scan, re-memorizing the drunk samples , low-pass filtering of a sequence of samples in the direction of a frame scan, page Filtered sequences in advance with respect to line scanning and subsequent low-frequency filtering in the direction of line scanning, characterized in that, in order to improve the accuracy of correction, when sampling dp of each section of the next field of the corrected television image, the auxiliary signal is subtracted from the television signal the signal level is characterized by a predetermined probability of exceedance, the auxiliary signal being subtracted m respective re-stored sample from the signal obtained as a result of repeated low-pass filtering. 2. The device dp implementation of the method according to claim 1, containing a synchronization unit, the first output of which is connected to the first input of the gating and smoothing unit, the other N outputs are connected to the corresponding inputs of the N sampler, each of which contains a block of sample sizes, the first input of which is intended to supply a television signal, the second input is connected to the first input of the memory unit and the corresponding output of the synchronization unit, and the output of the sample size calculation unit is connected to the corresponding input the house of the gating and smoothing unit and the second input of the memory unit, characterized in that, in each of the aral signal samplers, a sample signal shaping unit is inputted, the first input of which is connected to the output of the memory unit, the second input is connected to the output of the building block and smoothing, and the output is with the third input of the sample size calculation block. Sources of information received & attention during examination 1. USSR author's certificate for application N 2650693 / 18-09, cl. H 04 N 5/19, 1979 (prototype).