JPH0326066A - Original read circuit for facsimile equipment - Google Patents

Abstract

PURPOSE:To attain reproduction and recording of a thin line of an original without causing noise even when an output of an image sensor is small by applying contour emphasis processing through the selection of a contour emphasis coefficient in response to the level of the output of the image sensor. CONSTITUTION:An original 1 is read by an image sensor 2, converted into a white/black picture signal 3, a contour emphasis coefficient selection circuit 4 detects a peak value of a white level of a picture signal and outputs a coefficient selection signal 5 of contour emphasis corresponding to the level of the picture signal 3. A contour emphasis circuit 6 outputs an output signal 7 emphasizing the contour of the noted picture element of the input picture signal 3 according to a coefficient selection signal 5 stored to a terminal 8. The contour emphasis is increased when, e.g. the level of the picture signal 3 is large by the coefficient selection signal 5 and the contour emphasis is decreased when the level of the picture signal 3 is small and noise level is large. Thus, even when the output level of the image sensor is small, no noise is caused and a thin line in the original is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a document reading circuit of a facsimile machine, and particularly to a document reading circuit of a facsimile machine that performs correction processing on an image signal read from a document. [Prior Art] The document reading circuit of a conventional facsimile machine uses an image sensor that reads a document and converts black and white information in the document into an image signal, and an image signal output from this image sensor that emphasizes the outline of the image signal optimally under general conditions. Correction processing is performed using contour enhancement coefficients that allow for accurate image reproduction. [Problems to be Solved by the Invention] The document reading circuit of the conventional facsimile machine described above performs correction processing for edge enhancement regardless of the output of the image sensor. If this is done, the S/N ratio will deteriorate, noise will be emphasized, and noise will occur in the playback and recording at the receiver. In addition, if the contour enhancement coefficient is made small to prevent noise from being emphasized, the contour information will not be processed sufficiently, resulting in poor resolution, and even if the output level of the image sensor is high, it will be difficult to reproduce thin lines in the document. The disadvantage is that it makes your sex worse. [Means for Solving the Problems] A document reading circuit of a facsimile apparatus according to the present invention includes means for outputting a binary image signal read from a document, and a contour enhancement coefficient set according to the level of the image signal. The image processing apparatus includes means for outputting a selection signal, and means for emphasizing the outline of the image signal according to the coefficient selection signal. [Example] Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 1 is a document, 2 is an image sensor, 3 is a black and white image signal, 4 is an edge enhancement coefficient selection circuit, 5 is an edge enhancement coefficient selection signal, 6 is an edge enhancement circuit, and 7 is an edge enhancement circuit 6 8 indicates the output terminal.

A document 1 is read by an image sensor 2 and converted into a black and white image signal 3. The image signal 3 is input to an edge enhancement coefficient selection circuit 4 and an edge enhancement circuit 6. The edge enhancement coefficient selection circuit 4 detects the peak value of the white level of the image signal and outputs an edge enhancement coefficient selection signal 5 corresponding to the level of the image signal 3. Contour emphasis episode 1i'! 6 outputs to a terminal 8 an output signal 7 in which the outline of the pixel of interest 9-1 of the input image signal 3 is emphasized in accordance with the stored coefficient selection signal 5. The coefficient selection signal 5 is
For example, when the level of image signal 3 is high, the degree of contour enhancement is increased, and when the level of image signal 3 is low and the noise level is high, the degree of contour enhancement is decreased. FIG. 2 is a detailed block diagram of the edge enhancement circuit 6. The image signal 3 is A-D converted by an A-D conversion circuit 6-1 and sent to a shift register 6-2. Shift register 6-2 is 3
Two signals (signals for horizontal pixels 9-2.9-1.9-3 for original scanning as shown in FIG. 3) are transmitted to the arithmetic circuit 6-
3, determines the value of the pixel of interest 9-1, and performs horizontal contour enhancement. The signal on which the horizontal edge has been emphasized is sent to the line memory 6-4, and is sent to the third signal in the calculation circuit 6-5.
As shown in the figure, the signal calculation for pixels 9-4.9-1.9-5 is performed, the value of the pixel of interest 9-1 is determined, and a signal 7 with vertical contour enhancement is output. Ru. [Effects of the Invention] As described above, the present invention performs edge enhancement processing of a pixel of interest in an image signal by selecting an edge enhancement coefficient depending on the size of the output of the image sensor. However, it has the effect of being able to reproduce and record fine lines in a manuscript without producing noise.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a detailed block diagram of the edge enhancement circuit of this embodiment, and FIG. 3 is a pixel diagram for explaining the operation of edge enhancement of this embodiment. This is a plan view.

Claims (1)

[Claims] means for outputting a binary image signal read from the original;
A document reading device for a facsimile machine, comprising means for outputting an edge enhancement coefficient selection signal set according to the level of the image signal, and means for enhancing the edge of the image signal according to the coefficient selection signal. circuit.