SU1186533A1 - Device for monitoring sharpness of image outline - Google Patents

Description

The invention relates to printing and photography and is intended for objective quality control of reproduction.

The purpose of the invention is to improve the accuracy and reliability of the assessment of the quality of the transmission contours of the image by the reproduction system. FIG. 1 shows the differential operators of the boundary curve of contours; in fig. 2 — block diagram of the proposed device.

The device contains a controlled image 1, a scanner 2, a luminous flux splitter 3, photoconverters 4, an adder 5, amplitude selectors 6 and 7, a time selector 8, memory blocks 9 and a second adder 10.

The device works as follows.

The controlled image 1 (original, reproduction) is fixed on the scanner 2 so that the scanning direction is perpendicular to the contour of the part. The luminous flux reflected from image 1 is split into two streams with the help of a splitter 3 and fed to photo converters 4 having diaphragms with different aperture diameters at the entrance. The luminous flux that passes through the diaphragm with a smaller opening corresponds to a sharp image at the scanned point (main channel), and the flow that passes through the diaphragm with a large opening corresponds to a non-sharp image (auxiliary channel). In photoconverters, both streams are converted into an electrical signal and

are subtracted in the first adder 5. Thus, a differential signal is generated at the output of the last, proportional to the Laplacian of the image in the controlled

₅ point. This signal is fed to the amplitude selectors 6 and 7, fixing, respectively, the maximum and minimum values of the second spatial derivative in the drop tone zone (Fig. 1c). The signals from the outputs of these selectors are sent to the control inputs of the temporary selectors 8, to the information inputs of which the current values of the coordinate along the X axis continuously flow from the selector along which the contour of the image detail is scanned. At the time of receipt of the control signal at the output of the corresponding selector 8, the value appears, respectively, of the Xhax coordinates. or Hyain., which are in turn memorized in memory blocks 9. Meanings

20 of these coordinates come from the outputs of memory blocks 9 to the inputs of the adder 10, where the absolute value of the difference serves as an indicator of the sharpness of the image detail.

25 The obtained figures for the original and its reproduction are compared, the magnitude of the differences between them is judged on the quality of transmission of the frequency characteristics of the image by this reproduction system, since the value of the specified indicator does not depend on the magnitude of the drop in optical density in the contour zone, i.e. does not depend on amplitude distortion in the path of reproduction.

2

Claims (1)

DEVICE OF CONTROL OF SHARPNESS DETAILS OF THE IMAGE, containing a scanning device, a light splitter, photovoltaic converters and an adder, characterized in that, in order to improve the accuracy and reliability of the evaluation of the quality of the transfer of image contours, the device additionally contains amplitude and time selectors, memory blocks and a second adder, moreover the output of the first adder is connected to the inputs of two amplitude selectors of the maximum and minimum signals, the outputs of which are connected to the control inputs of the time selections Hur, data inputs are connected to the output of the scanning device outputs time gates are connected to inputs of memory blocks, memory blocks and outputs connected to inputs of the second adder. e (WITH 1186533 Fig / 1186533