SU1506588A1 - Device for adjusting cotntrast of stationary tv images - Google Patents

Abstract

The invention relates to a television technique. The purpose of the invention is to improve the quality of regulation by increasing the contrast of a still television image within the entire frame. The device comprises an amplifier 1, two switches 2 and 7, two limiters 3 and 8, a shaper 4 of a marker signal, an adder 6, a source 15 of reference voltages, an input 16 and an output 19 of the device, an input 17 of control pulses, an input 18 of an external control signal. The goal is achieved by introducing into the device an element OR 5, a multiplier 9, a switch 10, a peak minimum detector 11, a peak maximum detector 12, a subtracting unit 13 and a dividing unit 14. 2 Il.

Description

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The invention relates to a television technique and can be used to regulate the contrast of still television images, for example, in medicine for analyzing X-ray images.

The purpose of the invention is to improve the quality of regulation by increasing the contrast of a still television image within the entire frame.

Fig. 1 is an electrical, block diagram of a device for adjusting the contrast of still television images; figure 2 - timing charts of the device.

The device for adjusting the contrast of still television images (Fig. 1) contains amplifier 1, first switch 2, first stop 3, shaper 4 marker, element OR 5, summator 6, second switch 7, second stop 8, multiplier 9, third switch 10, peak minimum detector 11, peak maximum detector 12, subtraction unit 13, dividing unit 14, reference voltage source 15, device 16 for adjusting the contrast of still images, input 17 pulses detection, external input 1 the control signal output device 19 for adjusting the contrast of the still image pictures.

The device works as follows.

At the input 16 receives a video signal (Fig. 2, a). In amplifier 1, the video signal is amplified N times (Fig. 2.6) and arrives at the first inputs of the first switch 2 and shaper 4 of the marker signal, the second and third inputs of which receive the reference voltages 11 ,, respectively, Up, specifying the required range of video signal levels to be altered. At the output of the marker signal generator 4, pulses of the position of the extracted video signal levels U- are formed (Fig. 2, c), which control the first switch 2 and are combined in the N.PI 5 emitter with external control pulses Ho, (Fig. 2 , d), representing a packet of 1g pulses of frequency

5065884

rows for the faded part of the field and the image and coming to the input 17.

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The location pulses of the allocated video signal levels at the output of the first switch. 2, the corresponding portion is cut out of the amplified video signal, which in the first limiter 3 is clipped by the Uprit level (Fig. 2.6), which allows to select the required range of video signal levels (Fig. 2, e). The pulses from the output of the element OR 5 at the output of the second switch 7 extinguish the corresponding parts of the video signal to the level of the OPSE (. 2, e), and,; U (, ni -Van-n and, in addition, Utsu v “H Ug," "- the lowest possible video signal level. The same pulses replace the same video signal sections in the third switch 10 with the level of the reference voltage Uon4 (Fig. 2, g), and Uon4 Ugp,

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The highest possible video signal level. A peak minimum detector 11 determines the minimum value of the video signal (Fig. 2, g) in the frame of the visible part of the image, and the second limiter 8 cuts off the signal (Fig. 2, e) from the output of the second switch 7 and that caMijjM generates a signal ( Fig. 2, h), in which the black level of the drop corresponds to the minimum value of the kneaded video signal. The received video signal (Fig. 2, h) is fed to the first input of the multiplier 9 and to the input of the peak detector 12 of the maximum level, in which its maximum value in the image frame is determined. Block 13 subtraction generates a constant difference of the reference stresses Uoni U on i. When i changes the external control signal, this difference determines the constant dynamic range of the extracted video signal levels equal to the dynamic range of the video signal, therefore, at the output of the dividing unit 14, the required coefficient of increasing the limited video signal (Fig. 2e) to the video signal span is black. the white differential, which allows the output of the multiplier 9 to adjust the magnitude (Fig, 2, g). At the output of the adder 6 (output 19), the required output video signal is formed (FIG.

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Claims (1)

Apparatus of the Invention A device for adjusting the contrast of still television images and 1 comprising a series-connected amplifier whose input is an input of a device for adjusting the contrast of still television images, a first switch, a first limiter and an adder whose output is an output of a device for adjusting the contrast of still television images the shaper of the marker signal, the first input of which is connected with the amplifier input, and the control input Vågå switch, a second switch connected in series, the first signal input of which is combined with the input of the amplifier, and a second limiter. as well as a source of reference voltages, the control input of which is the input of an external control signal of the device for adjusting the contrast of still television images, the first video channel is connected to the second signal inputs of the first and second switches, BTqpoA output - with the control input of the first limiter and the second input of the driver marker signal, the third input of which is connected to the third output ten 15 15065886 allows a source of reference voltages, characterized in that, in order to improve the quality of regulation, vanity by increasing the contrast of a still television image. within the whole frame, the third switch connected in series, the first and second signal inputs of which are connected respectively to the input of the amplifier and the fourth input of the source of the reference voltage, and the peak 1 minimum level detector, the output of which is connected to the control input of the second limiter, are connected in series a subtraction unit, the first and second inputs of which are connected respectively to the second and third outputs of the source - 20 ka reference voltages, the division unit and the multiplier, the other input of which connected to the output of the second limiter, the output to the second input of the adder, the peak maximum level detector, whose input is connected to the output of the second limiter, and the output to the second input of the division unit, and also the OR element, the first input of which is connected to the output of the marker of the marker signal, the second input is the control pulse input of the device for adjusting the contrast of still television images, and the output is connected to the control inputs of the second and third switches. 25 thirty 35 ten , 20 15 , 20 , 20 25 , 20 thirty , 20 35