SU1539805A1 - Halftone-to-double-grade image converter - Google Patents

Abstract

This invention relates to technical cybernetics and can be used in digital image processing systems. The purpose of the invention is to improve the accuracy of the device. The device implements a method for extracting regions of variation of the drop curves in a video signal and improves the localization accuracy of these regions by selecting frequency-modulated signals. After converting the video signal on the first differentiating element, frequency modulation is performed according to the amplitude of the output signal. Due to the frequency selection, the frequency range corresponding to the luminous region of the background object is selected from this signal. To isolate the inflection point, the frequency modulated signal is converted to voltage and a second differentiation is performed. At the same time, the first and second comparators form rectangular pulses with durations equal to the lengths of the front and fall of the video signal. After the second differentiation, in order to clarify the localization of the points of inflection, frequency selection is again carried out with direct and inverse transformation. In this case, a narrow rectangular pulse with a duration equal to the inflection region is formed at the output of the third comparator. The signals from the three comparators are multiplied accordingly on the elements I and on the output of the trigger, when the phase matches the signals of the comparators, a rectangular pulse is formed, the duration of which is proportional to the length of the image. The item is NOT gated for gated

Description

the second 14 and third 15 comparators, the first 16 and second 17 And elements and the trigger 18. Point a in figure 1 is the device input, and point h is the device output.

The device works as follows.

A readout signal from a television sensor is applied to the input of the device (Fig. 2a). From the output of block 1, the differentiated signal is fed to the input of the unipolar signal shaper, where it is transformed from a heterogeneous field into a unipolar (figure 2, b). The received signal is fed to the input of block 5, where the frequency modulation of the input signal in amplitude is performed. The output frequency-modulated signal is fed to the input of a bandpass filter, the band of which is chosen based on the condition of a possible change of the front and fall of the image signal. The filtered signal is amplified in block 9 and demodulated in block 11 so that the output signal of block 11 is the voltage plots (Figures 2, e) proportional to the frequency of the input signal. The transformed signal after the first differentiation is fed to the inputs of blocks 15, 13 and 2. Comparing level in the block

15 is set to decrease the input signal, and a pulse of duration c is formed at its output. The level of compression in block 13 is tuned to the front of the input signal, and at its output a pulse of duration Ј f is formed. The control inputs of the comparators 15 and 13 are designed to turn on the comparators at different times: when the block 15 is gated, the block

16 is disabled and vice versa. It also allows for clock elimination.

on the video signal envelope. Signal

(Fig. 2, e) is differentiated a second time in element 2. Such an operation allows localizing the inflection points in the input signal, which corresponds to the areas of non-linear change in the brightness of the image. Physically, this corresponds to the boundary of the object and background. To clarify the position of the inflection point, the output signal from element 2 is processed similarly as in element 1 in blocks 6, 8, 10, and 12, in which the frequency modulation of the input signal, band-pass filtering and amplification are performed, followed by demodulation. The output from converter 12 is as shown in FIG. 2, g, and is fed to the input of comparator 14, where it is converted to a rectangular signal with a duration of n.

After processing the signal, rectangular pulses with durations Cc, b4, Cn are generated at the outputs of the comparators, which are fed to the corresponding inputs of the elements 16 and 17, at which the operation of multiplying the input signals is performed. The output pulses of the elements AND go to the inputs of the trigger setup 18. The pulse from the output of the element AND 16 sets the trigger to one state, and the pulse from the output of the element 17 sets the trigger to the zero state and thereby generates an output signal at the output of the trigger figure 2, h.

By processing the entire halftone image in this way, a two-gradation signal is generated on the video monitor connected to the output of the proposed device.

Claims (1)

Invention Formula A device for converting a halftone image into a two-gradation one containing two differentiating elements, two amplifiers, three comparators, two AND elements and a trigger, the input of the first differentiating element being the device input, the outputs of the first and third comparators are respectively connected to the first inputs of the first and second And elements, the other inputs of which are connected to the output of the second comparator, the outputs of the first and second elements AND are connected respectively to the installation input to the zero reset input. and whose output is the output device, and a m l h and south- o f e to the fact that, in order to increase the accuracy of the device, it comprises two transducer frequency - voltage converter, two voltage zhe. frequency, two bandpass filters, an analog inverter and a unipolar shaper; the output of the first differentiating element is connected to the input of the analog inverter, the control input of the first comparator and the input of the unipolar signal shaper, the output of which is connected to the input of the first voltage-frequency converter The output of which is connected to the input of the first bandpass filter, the output of which is connected to the input of the first amplifier, the output of which is connected to the input of the first frequency converter - voltage the output of which is connected to the information inputs of the first and third comparators and the input of the second differentiating element whose output is connected to the input of the second voltage converter is the frequency whose output is connected to the input of the second band-pass filter whose output is connected to the input of the second amplifier, output which is connected to the input of the second frequency converter - voltage, the output of which is connected to the input of the second comparator, and the output of the analog inverter is connected to the control input of the third comparator ora FIG. four USHLLA / H / JJH / UU at t Deprived t one L / Ive 2