JPH03262380A - Picture communication equipment - Google Patents

Abstract

PURPOSE:To attain excellent gradation reproduction by selecting an output data of a binarizing means as to a character area according to the result of image area discrimination and a binary picture data as to an image area other than the character area as a data of reception picture respectively. CONSTITUTION:An output data of a simpler binarizing processing section 25 is selected data to a character part by controlling a selection section 26 with a discrimination output of an image area discrimination section 22 and the data is outputted to an output terminal 27 and as to an image area other than the character part, the picture data inputted to an input terminal 21 is selected and outputted. Thus, when the picture data of the original subject to pseudo intermediate tone processing uniformly is received, the picture is decoded into a picture equal to that before the pseudo intermediate tone processing at a sender side as to the character area, the simple binarizing processing is implemented again. On the other hand, as to a photograph part other than the character area, such the processing is not implemented, Then excellent gradation is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image communication device such as a facsimile machine.

BACKGROUND ART Conventionally, in order to improve the gradation reproducibility of halftone images such as photographs, facsimile machines uniformly perform pseudo-halftone processing such as dither processing on the entire image of a transmitted document before transmitting the image.
Then, it distinguishes between text areas and halftone areas such as photographs in the transmitted document, performs simple binarization processing using a fixed threshold on the text areas, and performs pseudo halftone processing such as dither processing on the halftone areas. A 7-axis transmission device has been devised.

Problem to be Solved by the Invention When the latter type of facsimile machine sends a document containing a mixture of text and photographs, it is necessary to adaptively perform pseudo-halftone processing only on the halftone image area during image area discrimination. Therefore, on the receiving side, both text and photographic parts of the received document can be reproduced satisfactorily.

However, according to the former type of facsimile machine, when pseudo-halftone processing is applied to the entire transmitted original image, the gradation reproducibility of halftone areas such as photographs in the received original on the receiving side is good; Regarding the character area inside, there was a problem in that the characters were blurred due to the influence of pseudo-halftone processing, which appeared on the casing, and the image quality was greatly impaired.

The present invention has been made in view of the above-mentioned problems, and even when receiving original image data uniformly subjected to pseudo-halftone processing on the sending side, the gradation of the halftone portion is impaired. It is an object of the present invention to provide an image communication device that can obtain a received image with blurring of character parts removed without causing blurring.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides, in a reception system of an image communication device such as a facsimile device, a discriminating means for discriminating an image area of received binary image data, and a discriminating means for discriminating the image area of received binary image data; A conversion means for converting image data into multi-valued data, a filter means for performing low-pass filter processing on the converted output data by this conversion means, and a binary value for binarizing the processed output data by this filter means using one specific threshold value. and
Selection means for selecting the output data of the binarization means for text areas and the binary image data for image areas other than the text areas as received image data, according to the image area discrimination result of the discrimination means. It is equipped with the following configuration.

According to the above-described configuration, when the present invention receives image data of a document that has been subjected to pseudo-halftone processing on the sending side, the character area is compared with the image before pseudo-halftone processing on the sending side. Since the image is restored to an equivalent image and then subjected to simple binarization processing again, it is possible to remove the blurring of text areas caused by the pseudo-spread processing on the sending side, and on the other hand, the Since such processing is not performed on photographic parts, good gradation reproduction is possible.

Embodiment FIG. 1 shows a schematic configuration of a facsimile apparatus according to an embodiment of the present invention, in which 1 is a transmitting system and 2 is a receiving system.

In the transmission system 1, reference numeral 3 denotes an image sensor section for reading the transmission document, and 4 an analog/digital conversion section for converting an analog image signal inputted from the image sensor section 3 into a multivalued digital image signal. 5 is a binarization processing unit that performs dither processing as simple binarization or pseudo halftone processing of the digital image signal, 6 is a correction processing unit that performs correction processing regarding the character portion of the dithered image data, and 7 is a correction processing unit. An encoding section 8 encodes the image data processed by the processing section 6, and a modulation section 8 modulates the encoded image data into a signal that can be sent to a line.

In the receiving system 2, 9 is a demodulation unit that demodulates the signal received over the line, 1O is a decoding unit that returns the demodulated data to image data before encoding, and 11 is a correction process for the character part of the decoded image data. A correction processing section 12 is a recording section that records image data after correction processing on recording paper.

As shown in FIG. 2, the binarization processing section 5 has an input terminal 15.
A simple binarization processing unit 16 performs binarization processing using a fixed threshold value and a dither processing unit 17 performs dither processing on the input multi-valued digital image data signal, and selects the signal according to instructions from an operation unit (not shown). In the unit 18, the simple binarization processing unit 1
6 or the output data of the dither processing section 17 are selected and sent to the output terminal 19.

Correction processing unit 6 of the transmission system 1 and correction processing unit 11 of the reception system 2
have the same configuration, and as shown in FIG. 3, image area discrimination is performed on the binary image data input to the input terminal 21 based on the image area discrimination results, while the binary image data is manually converted. The unit converts the data into multivalued data, passes it through the low-pass filter processing unit 24, and then performs binarization processing again using a fixed threshold value in the simple binarization processing unit. By controlling , the output data of the simple binarization processing unit 5 is selected for the character part and output to the output terminal 21, but the image data input to the input terminal 21 is selected for the image area other than the literature part. The output is as follows. The number of image area discrimination copies stores the edge pattern that is a characteristic of the text area. By performing pattern matching with the edge pattern for each block of a predetermined size for the input image data, it is possible to distinguish between the text area and other areas ( (halftone area).

The operation of the facsimile apparatus configured as described above as a receiver will be explained in detail.

The received signal demodulated by the demodulation section 9 is decoded into binary image data by the decoding section 10, processed by the correction processing section 11, and then recorded in the recording section 12.

When pseudo-halftone processing is applied to the entire transmitted document on the sending side, if the binary image data output from the decoding section 10 is recorded in the IT recording section 12, the characters generated by the pseudo-halftone processing Since the blurred parts are still reproduced and the quality of the received original is poor, the correction processing section 11 applies correction processing to remove the blurred text parts only to the character areas.

The contents of this correction process will be explained with reference to FIGS. 4 to 7. 0) in each figure indicates the state of the image, (b)
indicates the density on the straight line AB of the image.

When dither processing (pseudo halftone processing) is applied to a multivalued image of a text portion as shown in FIG. 4, an image with notches as shown in FIG. 5 is obtained. If such a notch occurs in the received image, if it is recorded, the text will be blurred.

However, in the correction processing section 11, by passing the image of the text portion with such a notch through the conversion section and filter section 24, it is possible to create a blur with an intermediate level of gray as shown in FIG. This image is then binarized by a simple binarization processing section using a predetermined threshold value to obtain a binary image shown in FIG. It is clear that this image has the notches caused by dithering removed and is equivalent to the simple binarized image of the original image shown in FIG. Since the result of such processing is selected by the selection unit for the character area, a received document without blurred characters due to dither processing can be obtained.

Regarding the halftone region, since no correction processing is performed, the gradation reproducibility is not impaired.

Note that even if the transmitting side performs image area discrimination and performs simple binarization processing on the text portion and pseudo-halftone processing on the halftone portion, correction processing will still be applied to the text portion. , there are no negative effects from it.

Next, the operation as a transmitter will be explained. The analog image signal from the image sensor section 3 is input to the binarization processing section 5 via the analog/digital conversion section 4, subjected to simple binarization processing or dither processing, and input to the correction processing section 6. Here, a correction process similar to that of the correction processing section 11 of the receiving system 2 is performed on the character part, and then it is encoded by the encoding section 7, further modulated by the modulation section 8, and then sent to the line.

Even if the binarization processing unit 5 performs dither processing on the entire document, the correction processing unit 6 performs correction processing on the text portion, so even if the receiving side is a conventional facsimile machine,
It is possible to reproduce received originals without blurred text due to dither processing.

Although dither processing has been described as an example of pseudo halftone processing, the present invention can be similarly applied to cases where other pseudo halftone processing such as error diffusion processing is employed.

Alternatively, a single correction processing section may serve as both the correction processing section 6 of the transmission system 1 and the correction processing section 11 of the reception system 2, and the connection thereof may be switched between transmission and reception.

In the correction processing section 6 of the transmission system 1, image area discrimination may be performed using the multi-valued data output from the analog/digital conversion section 4, which enables highly accurate image area discrimination.

In the transmission system 1, in place of the binarization processing unit 5, a device is used that performs image area discrimination, performs simple binarization processing on character areas, and pseudo-halftone processing on halftone areas, and performs the processing. The output may be directly input to the encoder 7. An example of a device that performs such processing by image area is the Japanese Patent Laid-Open No. 6
Devices such as those disclosed in Japanese Patent Laid-Open No. 1-80965 and Japanese Patent Laid-Open No. 63-250274 can be used.

Effects of the Invention As is clear from the above explanation, the present invention provides a receiving system for an image communication device such as a facsimile machine,
a discriminating means for discriminating an image area of value image data; a converting means for converting the binary image data into multi-value data; a filter means for performing low-pass filter processing on the converted output data of the converting means; A binarizing means binarizes the processed output data using a specific threshold value, and according to the image area discrimination result of the discriminating means, the output data of the binarizing means is used for character areas, and the output data of the binarizing means is converted to images other than the character area. As for the area, since the configuration includes a selection means for selecting each of the binary image data as data of the received image, even when image data of an original that has been subjected to pseudo-halftone processing is received, , it is possible to remove the blurring of text areas caused by pseudo-halftone processing on the sending side, and good gradation reproduction is possible because such processing is not performed on photo areas other than text areas. This has the effect of

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a facsimile machine according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a binarization processing section, FIG. 3 is a schematic configuration diagram of a correction processing section, and FIGS. 4 to 7 2A and 2B are diagrams illustrating an image and a density change, respectively, for explaining the occurrence of blurring in a character portion due to pseudo halftone processing and its correction processing. 1... Transmission system, 2... Receiving system, 3... Image sensor section, 4... Analog/digital conversion section, 5... 2
Value conversion processing unit, 6... Correction processing unit, 7... Encoding unit,
8... Modulation section, 9... Demodulation section, 10... Decoding section, 11... Correction processing section, 12... Recording section.

Claims (1)

[Claims] a determining means for determining the image area of the received binary image data;
a conversion means for converting the binary image data into multi-value data; a filter means for performing low-pass filter processing on the converted output data of the conversion means; and a binarization of the processed output data of the filter means using a specific threshold value. According to the binarization means and the image area discrimination result of the discrimination means,
An image characterized by having a selection means for selecting the output data of the binarization means for a character area and the binary image data for an image area other than the character area as received image data. Communication device.