JPS59138166A - Picture signal processing device - Google Patents

Abstract

PURPOSE:To obtain a picture signal without a shadow signal by receiving a reflected light from an original scanned by light from a light source at plural photodetectors arranged in a different angle, obtaining a sum/difference signal of plural signals and subtracting an absolute value of the difference signal from the sum signal. CONSTITUTION:When an original plate 10 mounting a sticked original on which an original 7 is sticked at the upper surface is moved from the right to the left by a driver, a reflected light irradiated from the light source 11 passes through a photoelectric converter 12 and an A/D converter 16, and a shadow signal is obtained from P5 and a black ground signal is obtained from P6 to P7 in an output signal A2. On the other hand, a black ground signal is obtained from P6 to P7 in an output signal A3 of an A/D converter 17 and a shadow signal is obtained from P8. The shadow signal only appears in an output A4 of a subtractor 19 subtracting the signal A3 from the signal A2, the signal is brought into a unipolarity A6 by an absolute value generator 20 and since the black signal and all the shadow signals appear at an output A7 of an adder 18, the picture equality is improved without shadow by subtracting the signal A5 from the signal A6 at a subtractor 21.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image signal processing device that processes image signals including halftones.

Structure of the conventional example and its problems In the conventional image signal processing device including halftones, the structure shown in FIG.
As shown in FIG. 3, when scanning a second document 2 (hereinafter referred to as a pasted document) formed by pasting the first document 1 on its upper surface -1, the document being driven by the document table drive device 3 is scanned. Place the pasted original 2 on the table 4, irradiate it with light from the light source 6, convert the reflected light into a stain detection signal by the photoelectric converter 6,
An image signal A1 shown in FIG. 1 was obtained.

However, as shown in the signal waveform in Figure 1, the image signal A1 normally has a high level in the section from point P2 to P3 of the original 1, but a so-called shadow signal occurs at the edge position P4 of the original 1. . At another end position P1, a shadow signal may or may not be generated depending on the angle of the light source 6 or the photoelectric converter 6. These shadow signals are unnecessary as image signals and significantly impair image quality.

Purpose of the Invention The present invention has been made in order to solve the problems of the conventional art as described above, and it is possible to obtain an image signal of high image quality without shadow signals when an image signal is obtained by scanning a pasted original. The object of the present invention is to provide an image signal processing device that can perform the following steps.

Structure of the Invention In order to achieve this object, the present invention receives reflected light from a document scanned with light from a light source with a plurality of photoelectric converters arranged at different angles, and converts the obtained plurality of electrical By calculating the sum signal and difference signal of the signals and further subtracting the absolute value of the difference signal from the sum signal, an image signal free of shadow signals is obtained.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the image signal processing device of the present invention, and FIG. 3 is a waveform diagram of main signals in the embodiment. Pasted manuscript 8 with manuscript γ pasted on the top surface
is placed on a document table 10 driven by a document table drive device 9. Light from light source 11 illuminates pasted original 8, and reflected light enters photoelectric converters 12 and 13 arranged at different angles. Photoelectric converters 12 and 1
The output signals of amplifiers 14 and 15 are applied to the input terminals of amplifiers 14 and 15, respectively, and the output signals of amplifiers 14 and 15 are connected to the input terminals of A/D converters 16 and 17, respectively. Output signals A2 and A3 of A/D converters 16 and 17 are applied to both input terminals of adder 18 and subtracter 19, respectively.

The subtracter 19 outputs the difference between the signals A2 and A3 to an output signal of 4.
Output. The signal A4 also contains a negative value, and is turned into a positive signal A5 by the absolute value generator 20.

The subtracter 21 subtracts the output A5 of the absolute value generator 2o from the output signal of the adder 18, thereby generating a target image signal output A7.

A method of scanning a pasted original using the image signal processing device as described above will be described. For example, if a manuscript containing a black background from position P6 to P7 is pasted on top of manuscript 8,
Assume that positions P6 and P8 are on both sides of the document 7. now,
Assuming that the document table 1o is moved from right to left by the document table driving device 9, signals of various parts as shown in FIG. 3 are generated. In the output signal A2 of the A/D converter 16, a shadow signal appears at position P5, and a black background signal appears at positions P6 to P7.

Further, in the output signal A3 of the A/D converter 1, a black background signal appears at positions P6 to P7, and a shadow signal appears at position P8.

Since the subtracter 19 subtracts A by three times from the signal A2, the black background signals at positions P6 and P7 are not generated in the signal A4, and only shadow signals at positions P5 and P8 are output. However, since position P8 is a negative signal, the absolute value generator 20 converts it into a positive signal like signal A5. On the other hand, the signals A2 and A3 are added to the output of the adder 18, and the black background signal and all the shadow signals appear in the output. Therefore, by subtracting the signal A6 from the signal by the subtracter 21, the shadow signal is removed like the signal A7, and an image signal output containing only the black background signal can be obtained. That is, by using this image signal A7 as an input image signal for a facsimile machine, computer, etc., it is possible to reproduce an output image with high image quality and no shadows.

As described above, according to this embodiment, a plurality of photoelectric converters 12 and 13 arranged at different angles receive reflected light from a document, and a sum signal and a difference signal of a plurality of electrical signals obtained are obtained. By calculating , and then subtracting the absolute value of the difference signal from the sum signal, it is possible to paste even if the image contains halftones or a binary image, since it does not go through any binarization circuit. It is possible to easily obtain an image signal with high image quality and no shadow signal from a mixed original.

In the above embodiment, two photoelectric converters are provided, but four photoelectric converters may be provided diagonally on the document, or any number may be provided.

As described in detail, the present invention receives light from a document using a plurality of photoelectric converters arranged at different angles, and performs arithmetic processing on the obtained plurality of electrical signals without binarizing them. Therefore, it is possible to obtain a high-quality image signal without shadow signals even for images containing halftones or for pasted originals.

[Brief explanation of the drawing]

FIG. 1 (-) is a schematic configuration diagram of a conventional image signal processing device;
FIG. 2 is a block diagram showing an embodiment of the image signal processing device of the present invention, and FIG. 3 is a signal waveform diagram of the main part in the same embodiment. 7.8...Original, 9...--Document table drive device, 1°...Document stand, 11...Light source,
12.13...Photoelectric conversion device, 14.15...
... Amplifier, 16.17 ... A/D converter, 18 ... Adder, 19.21 ... Subtractor, 2o ... Absolute value generator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] a first means for photoelectrically scanning a document and generating electrical signals with each of a plurality of photoelectric converters arranged at different angles;
a second means for calculating a sum of the plurality of electrical signals; a third means for calculating a difference between the plurality of electrical signals;
a fourth means for calculating the absolute value of the electric signal obtained by the means; and a fourth means for calculating the difference between the electric signal obtained by the second means and the electric signal obtained by the fourth means. and sixth means for outputting a signal.