SU1241529A1 - Television system with compressing digital picture signals - Google Patents

Abstract

The invention provides an increase in the quality of the reproduced television image by increasing the accuracy of restoring the contours with smooth differences in brightness. At the transmitting side, an analog image signal from the transmitting television camera I through the A / D converter 3 is supplied to the memory unit 4 (PSU). In BP 4, information about seven adjacent image elements is simultaneously stored. The information about the six adjacent pixels of the BP 4 is supplied to the block 5 for calculating the average arithmetic values and to the comparison block (BS). When certain conditions are met, providing a selection of contours with a sharp difference in brightness, from BS 6 to BP 4 a Comparison signal is received. By this signal c, six-bit values of elements with an inverted low-order bit will be written to adder 7. When generating a signal, the Incomparison of the values of the elements is rewritten without change. Thus, pre-processing (correction) of the elements with (LK

Description

appropriate group. Adder 7: adds each element to the previous one, coming through the block 8 delay. The result of the summation (a seven-bit binary number) through divider 9 (by 2) and output register 10 enters the communication line II. The control unit 2 generates the corresponding signals. At the receiving side using the input register 12, control block 13, BP 14, blocks 15

The invention relates to a television technology and can be used in digital television image transmission processing systems.

The aim of the invention is to improve the quality of the reproduced television image by improving the accuracy of restoring the contours with smooth differences in brightness.

FIG. Figure 1 shows the electrical structure of a digital television image signal system; Fig. 2 shows the source graphs (CL diagram), processed using the well-known C diagram and the proposed (diagram I) of this signal. i

A television system with compression of digital image signals contains on the transmitting side a transmitting television camera (TCE) 1, control unit 2, analog-to-digital converter (ADC) 3, prc 4 memories, block 5 for calculating arithmetic mean values, block. 6 comparisons, adder 7, delay unit 8, divider 9, output register 10, transmitting side of the system through communication line I1 is connected to the receiving side, which contains input register 12, control unit 13, memory block 4, first block 15 calculating average arithmetic values, comparison unit 16, reproducing signal correction block 17, second block 1 8 calculating arithmetic average values, calculator 19, element ,, ,,. 20, D / A converter DTC) 21, video monitoring unit (WKB) 22 ,, TV system with digital compression x picture signals operates as follows.

and 18 calculations. arithmetic mean values, comparison unit 16, reproducible signal correction block 17, subtractor 19, AND 20, TSA 21 21 and video control unit 22 reproduce the image in which the contour with a sharp drop in brightness is restored or the contour is corrected with a smooth difference in brightness. 2 Il.

The analog image signal from the transmitting television camera 1, which is synchronized by the signal received at its input from the first output of control unit 2, is fed to the first input of ADC 3, where time sampling occurs (the sampling rate is 12 MHz), the level quantization and coding

readings of six bits of binary code. The analog-to-digital conversion procedure is synchronized by a signal fed to the second input of the A / D converter 3 from the second output of control unit 2, which contains a clock generator, frequency dividers and signal conditioners needed to synchronize all blocks of the transmitting part of the system.

The image signal samples, corresponding to its individual elements, from the output of the ADC 3 arrive at the first input of the memory block 4, containing seven series-connected groups, of 6 triggers (one trigger in the group for each bit). According to the signals arriving at the third input of the memory block 4 from the third output of the control block 2,

information is consistently progressed through all seven groups of Triggers,

Thus, in block 4 Pamdti. at the same time information is stored about all the seven adjacent picture elements. Information about six adjacent image elements from the outputs of memory block 4 is fed to the inputs of the calculator 5 for calculating the arithmetic mean

values and block 6 comparisons,

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recording into which is effected by a signal arriving at the second inputs of the said blocks from the fourth and fifth outputs of the control unit 2 and the next with a frequency half as large as the analog signal sampling rate.

Consequently, in block 5 of calculating the arithmetic mean values and block 6 of the comparison, the information about the group of image elements with numbers 1-6 is first recorded, then with numbers 3-8, and so on. Denote the first element in each group by the digit J, the second element by the digit II, etc. the sixth element is the number VI.

In block 5, calculating the arithmetic mean values, the average values of elements I and II (I average), III and IV (II average), and V and VI (III average) are calculated simultaneously, and then the average of I and II average is calculated. Arithmetic average value 1 and medium III, and medium II, enter the third input of comparator block 6, which verifies the equality of the arithmetic mean values of I and III of the middle and II medium, as well as the equality of G, II and III, and IV, V and VI elements.

Comparison unit 6 generates a Comparison Signal (CP) when the following conditions are met.

The arithmetic mean of t and III, the averages and the value II of the mean are the same. At the same time, at the output of the NAND element, the comparison unit 6 is turned on, a logical O signal is generated. The fulfillment of this condition is a resolution for the additional processing of this group of elements in the receiving part (as in the analog and the prototype). The three neighboring elements are not the same in at least one of the two groups of three adjacent elements (I, II, and III; IV, V, and VI). The same values of the corresponding elements both in the first and in the second group of three neighboring elements are characteristic of contours with a sharp drop. luminance.

When the above conditions are met at the output of the comparator unit 6, a CP signal is generated, which is preserved for a time interval equal to the duration of two adjacent elements.

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After shaping. CP or Signal Comparison (CP) with you-. the stroke (exit of the seventh group of flip-flops) of memory block 4, on the first input J into adder 7, the first element is first rewritten, and through cycle II an element. In this case, both .1 and II elements, in the presence of a CP signal (at the output of the comparison block 6), are rewritten with 50 inverted) with the lowest-order bit (with minimal error),. in this case, the inversion of the low-order bit is effected by the signal arriving at the third input of the 4-block block. In the next cycle, due to the fact that the CP signal is already generated at the output of the comparator unit 6 (if the specified conditions are not fulfilled simultaneously), the III element in the adder 7 is rewritten without change. IV element is also rewritten, etc.

So when doing. the specified conditions in the transmitting part of the system, prior to the implementation of the modified linear Paley (Walsh) transformation, i.e. Before performing the averaging operation of the original image over non-intersecting groups of two adjacent line elements, the I and II elements of the corresponding group are pre-processed (correction), and this correction is performed by inverting the lowest 35 bits of these elements, resulting in a modified Peli (Walsh) transformations, the corresponding sequence (group) of averaged elements (J 40 average, II average and III average) for the receiving part will no longer be Resolution for additional processing (correction) of the reproduced signal according to the algorithm for restoring circuits with abrupt differences in brightness (according to the first algorithm).

If the first of the specified conditions is not fulfilled, additional processing by the first algorithm in the receiving part is not performed and, therefore, there is no need for preliminary processing (correction). If the second condition is not fulfilled, the corresponding elements form a group, which is characterized by a contour with a sharp difference in brightness. Such a group of elements after the modified Peley (Walsh) transformation and additional processing (correction) according to the first algorithm in the receiving part is completely restored and, therefore, it should not be preprocessed.

From the first output of memory block 4, as already noted, six-bit binary numbers corresponding to discrete samples (elements) of the image are successively fed to the first input of adder 7 and recorded in the corresponding group of its triggers according to the signal received by the third adder 7 the sixth output of control unit 2. In adder 7, each element with an even number is summed with the previous element with an odd number, which comes from the output of the adder 7 through the delay block 8 to the second input of the adder 7,

The control of the delay unit 8 is performed by a signal arriving at its second input from the seventh output of the control unit 2. The delay time is equal to the duration of one image element. . : The result of summation (a seven-bit binary number) from the output of the matrix 7 is fed to the first input of the divider 9, in which the division operation is performed by 2. It is performed by shifting the seven-digit number to the right by one bit.

From the output of the divider 9, the processed pixel samples are fed to the first input of the output register 10, and from its output to the line

connection 1I, while synchronizing

The bots of the divider 9 and the output register 10 are carried out by signals arriving at their second inputs from the eighth and ninth outputs of the control unit 2, respectively.

The processed by the transmitting part of the system according to the algorithm of the modified Paley linear transformation (Walig), the sequence of the digital stream corresponding to the average values of two adjacent elements of the original image, from the communication line 11 goes to the first: input of the input register 12, where the consecutive six-bit binary numbers , corresponding to individual average values (I average, II average, III average, etc.) are converted into parallel

code. In addition, it provides for a delay in the accepted averaged values (it contains five groups of triggers), and in the second, third, and fifth groups six triggers are included, a. in the first - seven. The presence of an additional trigger in the first group is necessary in order to translate consecutive binary numbers into parallel ones. These operations are performed using the 7th, 8th, 9th, 10th, 11th and 12th pulse sequences, which are received from the first output of the control unit 3. After in the fifth, fourth, and second groups of triggers of input register 12, six-bit binary numbers are written, corresponding to I, II, and III (II, III, and IV; III, VI, and so on), they are using the 7th pulse sequence, they will simultaneously rewrite to memory block 14 containing three groups of triggers, each group containing six triggers, From the first output of memory 14 blocks 1 and III (II and IV; III and V, etc.) The means are fed to the first block 15 for calculating the arithmetic mean values (the control of this block is carried out with the help of the 9th pulses from the third output of control unit 13). The result of calculating the average of I and

III (II and IV ;; III and V, etc.) of the average is fed to the first input of the comparison block 16, at the second input of which at this moment there is information about II (III, IV, etc.) to the average from the second output of the memory block 14.

In block 16 comparison, a comparison is made of the arithmetic mean of 1 and II (II and IV; III and V, etc.) average: with the value of II (III ;;

IV, etc.) average. If the comparison block 16 establishes that, as a result of the comparison, the arithmetic mean value of 1 and III (And and IV; III and V:

etc.) averages and value II (III, IV to: etc.) are equal to the average (which is typical for circuits with sharp differences in brightness), then at the first output of the comparison block 16 (control of this block is carried out using 10 th consecutive un

ny ibcoB, coming from the fourth output of the control unit 13), a CP signal is generated in the form of a logical 1U that is fed to the fourth input of the playback signal correction block 17 and, thus, in it in place of the first half II (III, IV, etc.) the average repeats the value of 1 (the foregoing) of the middle (II middle, III middle, etc.), and on the place of the second half of II middle (III middle, IV middle, etc.) - the value of III (subsequent) average (IV average, V average, etc.). coming in from the second input

Register 12. Thus, the contour with a sharp difference in luminance will be restored. If the comparison block 16 establishes that the arithmetic mean of t and III (II and IV; III 4 V, etc.) of the means differs from the value of II (III, IV etc.) is average, then at the first output of this block a signal CP (logical o) is formed. At the same time on the second (inverse)

: At the beginning of this block, logical 1 will be formed.

Simultaneously, the values of G, II and III (II, III and IV; III, IV and V, etc.) of the average from the first output of memory block 14 are fed to the first inputs of the second block 18 for calculating the arithmetic mean values of I ,.

and subtractor 19.

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In the second block 18 of calculating the arithmetic mean values (the control of this block is carried out using the 13th sequence of pulses coming from the eighth output of the control block 13) the arithmetic mean values of 1 and II, as well as II and III averages (II and III; III and III IV averages, etc.), and in subtractor 19 (the control of this block is carried out using the 14th sequence of pulses coming from the ninth output of control block 13) the difference between 1 and III is calculated (II and IV; III and V, etc.) are medium and thus determined whether or not the luminance difference. If this difference exceeds a certain threshold (in this case, 16), then the corresponding enable signal (logical 1) from the output of the subtractor 19 is fed to the first input of the AND 20 element. If, at the same time, the second output of the comparison unit 16 (pa

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the second input of the element And 20) logical I will be formed (the condition of additional processing according to the first algorithm is not met, i.e. there is no circuit with a sharp difference in brightness), then at the output of the element 20, at the time determined by the presence of a pulse ( logical 1) in

It is the th sequence (this sequence of pulses is applied to the third vhrd of the element AND 20 from the seventh

output of control block 13) logical 1 will be formed, which is fed to the fifth input of block 17 of correction of the reproduced signal (the first input of this block at this time will receive a signal corresponding to logical O, which does not allow processing according to the first algorithm) and is written to the appropriate trigger. This signal provides digital recording of the sequence (using the 6th pulse sequence) in the triggers of the 17-unit correction of the reproduced signal only from the output of the second block 1 8 of calculating the average and metric values, which is performed as follows: at the time. nor, corresponding to the first half

II (III, IV, etc.) average in the triggers of the block 17 correction of the reproduced signal, the arithmetic average value I and II will be recorded

(II and III; III and IV, etc.) of averages, and at the point in time corresponding to the second half of II (III, IV, etc.) the average is the arithmetic value of II and III (III and IV; IV and V etc.) medium.

Similarly, the sequence of pulses in the triggers of the block 17 correction of the reproduced signal in place of the second half of II (III, IV, etc.) of the middle records either the average of II and III (III and IV; IV and V, etc.) of the average or III (IV, V, etc.) is average. From the foregoing, it follows that the second additional processing algorithm allows the corresponding contour of the image to be restored more smoothly.

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In other cases, i.e. in the case of In other words, when the conditions corresponding to at least one of the two specified algorithms in the triggers of the 1 7 correction block of the reproduced signal, are all averaged, will not be performed.

The values from the second output of the input register 12 will be written in such a sequence as they were received from the communication link 11. This means that in these cases an additional treatment is required. bang no. one of the two algorithms will not be produced,

From the output of the reproduced signal correction block 17, the corrected (when one of the additional processing conditions is fulfilled) the digital image signal is fed to the DAC 2, where the analog signal is restored.

From the output of the D / A converter 21, the reconstructed analogue television signal is fed to the video monitoring unit 22.

Thus, during the implementation of additional processing in the receiving part of the system, one of two algorithms is implemented. The first of them allows you to restore the boundaries of the contours with a relatively sharp difference in brightness, and the second with a smooth difference in brightness. Here, priority is given to the first algorithm. This means that with equal average arithmetic values of 1 and III averages (II averages; III and V averages, etc.) with a value II of averages (III averages. IV averages, t, d,) (which is typical for contours with a relatively sharp difference in luminance, blocking the processing of this part of the image is provided by the second algorithm, which is done by applying a logical O from the inverse output of the I6 comparison unit (at the same time, the forward output of this block has a CP signal as logical 1) to the input element and 20. When failure (gkaza condition of equality at the second (inverse) output of the comparison block 16, logical 1 will be formed (the SRD signal, which is the resolution for processing the given section according to the second algorithm. But for this, as indicated, the difference between III (II and IV; III and VH, etc.) the average | must exceed the threshold value, that is, the decimal number 16 (there should be a difference in brightness). This threshold was chosen experimentally, taking into account the visual perception of the man. On the other hand, it is necessary

the presence of the specified threshold, since otherwise, the second algorithm will process all elements (except elements located on the edges of the contours with a sharp difference in brightness) of the reproduced image.

The operation of the proposed system is illustrated in Fig. 2, where a contour with a smooth difference of brightness is considered.

Suppose there is a contour with a smooth difference in luminance, the corresponding signal of which for one line 5 of the decomposition of the image is m). This corresponds to the sampled and quantum image signal. In Fig. 22G, the numbers of quantization levels in the vertical direction are expressed with decimal numbers, and in the Horizontal direction, the numbers of the original sampled values (samples), expressed in 5 Arabic numerals, are 2. After converting a given portion of the line using the modified Paley (Walsh) linear transformation algorithm, the corresponding change in luminance will be 0 represented by graph 2.

Consider the work of the receiving side of the system for this fragment.

After the six-bit binary numbers corresponding to the individual average values are written in the input register 12, from the first output of the input register 12 each of them will be fed to the first input of the memory block 14. From this block after recording three neighboring averaged values in this case, 1st, 11th and 111th), these values are fed to the inputs of the first block 15 for calculating the arithmetic average of the second block 18 for calculating the average for the arithmetic mean and subtractor 19. The first block 15 of calculating the arithmetic mean values is calculated by the arithmetic mean value of T and ill of the mean, which in this case is 35. This value is then fed to the first-input. comparison unit 16, to the second input of which at the same moment of time from the second output of memory 14 unit 5, the value II of the average is applied (in

in this case, a hexadecimal binary number, the tenth equivalent of which is 30). In block 16 comparison

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the arithmetic mean of T and III means (number 35) is compared with the value of the second average (number 30). In that case, . when these values are equal to each other, then the comparison unit 16 generates a CP signal (logical 1 on the first, i.e. direct output of this block and logical O on the second, i.e. inverse output), otherwise L is the CP signal (logical O on the first output and logical I on the second output). Due to the fact that in the case under consideration the average value of I and III of the average does not deteriorate with the value of III of the average, the comparison unit 16 generates a CP signal (logical 1 at the second output). Which is one of the demanding conditions (which should be simultaneously) to allow the fragment to be processed by the second algorithm.

Simultaneously with the process described, in the second block 18 of calculating the arithmetic averages, the arithmetic average is calculated for both the G and II averages and II and III averages, and in subtractor 9 the difference between the I and III averages is determined. If this difference exceeds the value of a predetermined threshold (in our case 16), then a signal corresponding to logical 1 is formed at the output of reader 19 (this signal is one of the two necessary conditions for the realization of additional processing using the second algorithm), Otherwise, the signal corresponds to the logical O. In the considered case, the difference between the I and III averages is 40 (it exceeds the set threshold) and, therefore, the subtractor 19 outputs the signal corresponding to the logical I. This signal together with the signal supplied from the output of the comparison unit 16 is a resolution for implementing the additional processing according to the second algorithm. Consequently, at the time corresponding to the moment of supplying logical I to the second input of element AND 20, which the control unit 13 allocates, the output of element And 20 generates a signal corresponding to logical 1. This signal is fed to the input of block 17 of the reproduced signal correction and allows

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to carry out., additional processing according to the second algorithm. Consequently, in this case, in the correction signal correction block 17, the arithmetic average values 1 and II of the average and III and II of the average, and from the output of the second an arithmetic mean value calculation unit 18 is supplied to the fifth input of a playback signal correction unit 17. The signal recovered in this way is represented by graph 2b.

From a comparison of 2D, B, B graphs, it follows that the additional processing of fragments with smooth luminance drops according to the second algorithm can significantly improve the quality of the reproduced image. In FIG. 2, Arabic numerals in the horizontal direction denote elements of the original image, Roman numerals. ramie - elements of the transformed image (averaged elements), and Arabic numerals in the vertical direction - numbers of quantization levels.

Claims (1)

Invention Formula A television system with a compression of digital image signals containing on the transmitting side serially connected transmitting television-camera, analog-to-digital converter. memory unit, adder, divider and output register, serially connected arithmetic mean value calculator and comparison unit, connected between the second output of the memory unit and the second input of the memory unit, the second input of the comparison unit is connected to the third output unit of the memory unit This as well as the delay unit connected between the output and the second input of the adder and the control unit, the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth outputs of which are connected respectively to the input of the transmitting television cameras the second input of the analog-to-digital converter, the third input of the memory unit, the second input of the arithmetic average calculation unit, the third input of the comparison unit, the third input of the adder, the second the input of the delay unit, the second input of the divider and the second input of the output register, on the receiving side are the serially connected input register, the memory block, the first block for calculating the arithmetic mean values and the comparison block whose second input is connected to the second output of the memory block, sequentially connected diffro-analogue converter (DAC) and video control unit (WKB), control unit, the first, second, third, fourth and fifth outputs of which are connected respectively to the second inputs of the input register, pa block ti, the first block calculating mean values of the video control unit and the third input of the comparison block-guide differs in that, in order to increase the quality of the reproduced video image by povsheni accuracy reduction with smooth contours luminance differences, on the reception side in S S7 1 / 8.2. Editor T. Parfenova Compiled by I. Gracianska Tehred O. Gortvay Proofreader T. Kolb Order 3616/58 Circulation 624 Subscription BNIIPI State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 -Production and printing company, Uzhgorod, Projecto st., 4 It introduced the second arithmetic mean value calculation unit, the subtractor, the And element and the correction block of the reproduced signal, the output of which is connected to the first input of the DAC, and the first, second, third, fourth and fifth inputs are connected respectively to the sixth output of the control unit, the second the output of the input register, the output of the second block for calculating the arithmetic mean values, the first output of the comparison block and the output of the element I, the first, second and third inputs of which are connected respectively to the output of the subtractor, the second output ohm comparison unit and seventh output.m of the control unit, the eighth and ninth outputs of which are connected respectively to the first inputs of the second calculation unit arithmetic mean values and subtractor, the second input of which is combined with the second input of the second block for calculating the arithmetic mean values and the connection chen to the first output of the memory block. I S $