SU788433A1 - Device for correcting gradation characteristic of reproduction apparatus - Google Patents

Description

(54) DEVICE FOR CORRECTING THE GRADATIONAL CHARACTERISTICS OF THE REPRODUCTION APPARATUS

one

The invention relates to an image processing technique and can be used to correct the end-to-end gradation characteristics of photographic, printing, television and other image reproduction processes.

A device for correcting the gradation characteristic of a reproduction apparatus is known, which contains two analysis units located in front of the analyzing scanner cylinder of the reproduction apparatus, a synthesis unit located in front of the synthesizing scanner cylinder of the reproduction apparatus, and also the first unit of payload 1.

However, the known device is complex due to the presence of two analysis units.

The purpose of the invention is to simplify the device by eliminating the second analysis unit.

To achieve this goal, an A / D converter, a D / A converter, a control unit, a second memory block, a binary counter, a first and a second switching unit, a data input unit, a function for calculating an additional correction function, an angular sensor are introduced into a known device for correcting the gradation characteristic of the reproduction apparatus. the position of the development cylinders is mechanically connected with the analyzing

J and the synthesizing spreading cylinders of the reproduction apparatus; the output of the angular position sensor of the expanding cylinders is connected to the input of the control unit, the output of which is connected to the trigger input of the analog-digital converter and the clock input of the binary counter, the output of which is connected to the recording input of the first memory block and the first the input of the first switching unit, the output of the analysis unit is connected to the information input of the analog-digital converter,

15 whose output is connected to the first input of the second switching unit and to the address input of the second memory unit, to the recording input of which serially connected data input unit and calculating function of additional correction are connected, the output of the second memory unit is connected to the second input of the second switching unit, to output which the address input of the first memory block is connected, and the output of the first memory block is connected to the second input of the first switching unit, the output of which is connected via a digital-to-analog converter to go block synthesis.

The drawing shows a structural electrical circuit of the proposed device.

A device for correcting the gradation characteristic of a reproduction apparatus contains a synthesizing developing cylinder 1 of the reproduction apparatus, analyzing the developing cylinder 2 of the reproduction apparatus, a sensor 3 of the angular position of the developing cylinders, a synthesis unit 4, an analysis unit 5, a control unit 6, a digital-analogue converter (DAC) 7, an analogue digital converter (A / D converter) 8, binary counter 9, first and second switching blocks 10, 11, first and second blocks 12, 13 of memory, block 14 of data entry and block 15 for calculating nktsii additional correction.

The device works as follows. In p; : the test production test reproduction 6, 10 switching connects the exhaust ;; binary counter 9 directly to the inputs of the DAC 7. When scanning, the reference clock from sensor 3 is fed to the input of control unit 6, which on each line forms 1.2 bursts of pulses from the reference frequency in a strictly defined angular position of the synthesizing and analyzing sweep cylinders.

The pulses arrive at the input of a binary counter 9, at the output of which a sequential binary code from 2 to 2 is formed (where n is the number of binary bits). The code generated by the binary counter 9 is converted by means of a DAC 7 to a linearly increasing voltage supplied to the input of the synthesis unit 4. The image obtained as a result of the synthesis, in accordance with the physics of this process (photographic, polygraphic, etc.), contains a semi-continuous continuous scale, and a nonlinear one, due to the gradation distortions introduced by the image synthesis process.

In the correction programming mode, the test reproduction obtained by the corrected technological process is installed on the analyzing scan cylinder 2. The second switching unit 11 connects the outputs of the A / D converter 8 to the address inputs of the first memory block 12. During the scan of the test reproduction, the control unit 6 in full compliance with the test reproduction manufacturing mode forms a burst of pulses. Each burst of a burst initiates the A / D converter 8 and simultaneously changes the state of the binary counter 9, and the state of the latter is each time stored in the first memory block 12 at the address defined by the output code of the A / D converter 8. At each time point, the code at the output of the A / D converter 8 is numerical expression of the optical density of this area of the analyzed test reproduction. Therefore, in the process of sequential arrival of the burst pulses to the input of the ADC 8 start and the counting input of the binary counter 9, the output of the ADC 8 contains a test reproduction density code corresponding to the density code of the test original simulated by the binary counter 9, and differs from it by the magnitude of the gradation distortions. From each resulting pair of corresponding values, the ADC code 8 is used as the cell address of the first block 12, and the binary counter code 9 as the number stored in this cell.

In the correction mode for the analyzing scan cylinder 2, the reproduced original is set, and the first block 12 is switched to the reading mode. During the scanning of the original, the signal at the output of the analysis block 5, proportional to the optical density of the original, is subjected to analog-digital conversion. If the density code from the output of the A / D converter 8 goes through the second switching unit 11 to the address inputs of the first memory unit 12, the value of the function inverse to the gradation characteristic of the process is read from the readout outputs of the latter.

The read code goes to the DAC 7, the output of which is connected to the input of the synthesis unit 4. As a result of the synthesis, according to a given technological process, an image is obtained with a linear gradation characteristic and gamma of reproduction.

Have 1.

However, there is often a need for a gradative transformation of the original.

by a given law. In order to extend the functionality, a second memory block 13, a block 14 and a block 15 are introduced into the device. These elements implement an additional gradation correction. The operator, using block 14, enters input data (coordinates of several points of the specified conversion function) into block 15, which automatically approximates the entire function and calculates its values, writing them to the second block 13

memory

When the device operates in the correction mode with additional correction, the second switching unit 11 connects the read outputs of the second memory block 13 to the address inputs of the first memory block 12. Now the code from the output of the ADC 8 goes to the address inputs of the second memory block 13, where the corresponding code of the additional correction function is read at this address, which, in its

the queue is the address at which the corresponding value of the inverse transform function of the reproduction process is read from the first memory block 12. The code from the outputs of the first unit 12 PA

Claims (1)

Claim An apparatus for correcting gradation characteristics that the reproduction appara- _claim, comprising two of the analysis block disposed before deploying cylinder analyzing the reproduction apparatus, the synthesis unit disposed before deploying cylinder synthesizing the reproduction apparatus, as well as the first memory block 20, characterized in that, in order to facilitate devices due to the exclusion of the second analysis unit, an analog-to-digital converter, a digital-to-analog converter, a control unit, a second memory block are introduced, a military counter, first and second switching units, a data input unit, an additional correction function calculation unit, an angular position sensor of the deploying cylinders mechanically coupled to the analyzing and synthesizing deploying cylinders of the reproduction apparatus, while the output of the angular position sensor of the deploying cylinders is connected to the input of the control unit, the output of which is connected to the start input of the analog-to-digital converter and the clock input of the binary counter, the output of which is connected to the input for From the first memory block and the first input of the first switching block, the output of the analysis block is connected to the information input of an analog-to-digital converter, the output of which is connected to the first input of the second switching block and the address input of the second memory block, to the recording input of which are connected in series the data input block and block for calculating the additional correction function, the output of the second memory block is connected to the second input of the second switching block, the output of which is connected to the address input of the first memory block and, and the output of the first memory block is connected to the second input of the first switching block, the output of which is connected to the input of the synthesis block through a digital-to-analog converter.