JPH05137005A - Image adjustment device for image processing system - Google Patents

Abstract

(57) [Summary] [Construction] With respect to an image signal that has undergone data compression based on the run-length coding method, each run-length code is detected by the image boundary detection circuit 23, and the expansion circuit 25 or the contraction circuit 26 detects the phase difference. The length information of preceding and following run length codes is relatively corrected. [Effects] The signal processing circuit 2 having a simple configuration removes faint lines and dot-like stains on an image without using complicated processing means or a large-capacity storage device like a full-scale image processing device. Thus, it is possible to perform more delicate and effective image adjustment than the density adjustment in the conventional image reading device 4 and the image recording device 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing system, such as a facsimile machine, which performs data compression based on a run length coding method for image signals.
The present invention relates to an image adjusting device for removing line blurring, dot-like dirt, and the like on an image signal.

[0002]

2. Description of the Related Art In a facsimile apparatus, an image of an original is read by an image reading apparatus, converted into an image signal, data compression based on a run length coding system is performed, and then modulated by a modulating apparatus to a telephone line. It is designed to be sent out. Also, the image signal sent via the telephone line is
After demodulating with a demodulator and expanding the compressed data,
The image recording device prints.

Here, the run-length coding method is a method in which, when image signals of the same color are continuous, this is converted into a code combining color information and length information thereof. An image signal handled by an image processing system such as a facsimile machine often has a long continuous background color or line or surface color of an original document. Therefore, a large compression ratio can be expected by this run length encoding method, and the data compression Widely adopted as the basic method of.

Further, in the above-mentioned facsimile apparatus or the like, an image reading device or an image recording device is provided with a density adjusting function so that the density of an image signal to be read or an image to be printed can be adjusted.

[0005]

However, in order to perform more delicate image adjustment with a conventional facsimile apparatus or the like, it is necessary to store a large number of pixel data for image processing before image signal compression, The capacity of the storage device becomes too large, resulting in an increase in the cost of the device. Moreover,
In order to perform full-scale image processing, it is necessary to perform two-dimensional processing considering not only the main scanning direction of the image reading apparatus but also the sub-scanning direction orthogonal to the main scanning direction. However, it is not practical for a facsimile machine or the like, which has a large limitation on the apparatus cost.

For this reason, the conventional facsimile apparatus has a problem that it is inevitable to give up finer image adjustment than the density adjustment in the image reading apparatus or the image recording apparatus.

In view of the above situation, the present invention corrects an image signal after data compression in a facsimile apparatus or the like, thereby performing extremely effective image adjustment with a simple apparatus, though not so much as full-scale image processing. It is an object of the present invention to provide an image adjusting device capable of performing the above.

[0008]

The image adjusting apparatus of the present invention is an image adjusting apparatus for an image processing system for processing an image signal data-compressed by a run-length coding system, and has undergone data compression. The image boundary detecting means for detecting each run length code from the image signal and the image boundary changing means for relatively correcting the successive run length codes detected by the image boundary detecting means are provided. The purpose is achieved.

[0009]

When a run-length code of a specific color and a run-length code of another color are adjacent to each other, the image boundary detecting means detects these run-length codes, and the image boundary changing means detects one of the run-length codes. The length information is changed to a longer one, and the length information of the other run length code is changed to a relatively shorter one. Further, at this time, when the length information of the other run length code becomes zero, this run length code is deleted and the run length codes of the same color before and after are merged into one run length code. Then, for example, when the image of the line has faintness or unevenness, the line can be connected and corrected by shortening or deleting the image signal of the background color portion. Also,
Even when dot-like stains are generated due to noise of the image reading device, the stains can be removed by deleting the dot-like image signals.

As a result, according to the image adjusting apparatus of the present invention, it is possible to perform more delicate image adjustment than the conventional density adjustment by removing the blurring of lines and the dot-like stain. Moreover, since simple image processing is performed on the data-compressed image signal along the main scanning, no complicated processing means or large-capacity storage device is required unlike a full-scale image processing apparatus.

[0011]

EXAMPLES The present invention will be described below with reference to examples.

1 and 2 show an embodiment of the present invention.
The present embodiment is an image adjusting apparatus used in a facsimile machine. As shown in FIG. 2, the facsimile machine is connected to a telephone line via a modulator / demodulator 1. The modulation / demodulation device 1 is connected to the compression / decompression device 3 via the signal processing circuit 2. The compression / expansion device 3 is also connected to the image reading device 4 and the image recording device 5, respectively.

The image reading device 4 carries out main scanning of an original image by means of photosensors arranged in a one-dimensional manner, and carries out subscanning by moving the photosensor or the original in a direction orthogonal to each other, whereby two-dimensional images are obtained. Is a device for converting the original document image into a serial image signal. The image recording device 5 is a device for converting a serial image signal into a two-dimensional image and printing it by moving the thermal paper in a direction orthogonal to the one-dimensional thermal head.

The compression / expansion device 3 performs data compression on the image signal converted by the image reading device 4 based on the run length coding method, sends the data to the modulation / demodulation device 1 via the signal processing circuit 2, and at the same time the modulation / demodulation device. 1 is a device that expands a data-compressed image signal sent from a signal processing circuit 2 to an original image signal for each pixel. Further, the modulation / demodulation device 1 modulates the image signal data-compressed by the compression / decompression device 3 with a voice band signal of a predetermined frequency and sends it out to the telephone line, and the voice band signal sent from this telephone line is used as the original data. It is a device that demodulates into a compressed image signal.

The signal processing circuit 2 is a circuit for adjusting the image of a data-compressed image signal, and as shown in FIG.
At the time of transmission, the compression / expansion device 3 is switched via the changeover switch 21.
The input image signal is input, and the processed image signal is output to the modulation / demodulation device 1 via the changeover switch 22. At the time of reception, the image signal from the modulation / demodulation device 1 is input via the changeover switch 21, and the processed image signal is output to the compression / expansion device 3 via the changeover switch 22.

The signal processing circuit 2 includes a changeover switch 21.
The image signal input from is sent to the image boundary detection circuit 23.
The image boundary detection circuit 23 is a circuit for detecting the color information and the length information for each run length code from the image signal to which the synchronization information and the like are added and the data is compressed. The output of the image boundary detection circuit 23 is connected to the expansion / contraction switching circuit 24. The expansion / contraction switching circuit 24 is a circuit that switches between the expansion circuit 25 and the contraction circuit 26 to process the output of the image boundary detection circuit 23. When the facsimile apparatus handles a black and white binary image signal, for example, if the currently input black run length code is used, the expansion circuit 25 changes the length information of this run length code to a longer one. , Which is a circuit for changing the length information of the white run-length code that follows to a shorter length. Further, the contraction circuit 26 changes the length information of the run length code to a longer one, for example, if the current input is the white run length code, and the length of the black run length code following the run length code is changed. It is a circuit that performs processing to change the information to be shorter by that amount. These expansion circuit 25 and contraction circuit 26
In the above, the length information is changed, for example, by one pixel in one processing, and the number of times of this processing can be adjusted appropriately. If the number of times of processing is set to zero, the original image signal can be output as it is. The image signal thus processed by the expansion / contraction switching circuit 24 is sent to the changeover switch 22 via the signal shaping circuit 27. As the expansion circuit 25 and the contraction circuit 26, conventionally known expansion circuits and contraction circuits can be used by returning from adjacent run length codes to pixels. The signal shaping circuit 27 is a circuit that adds synchronization information and the like to the processed image signal again to restore the original image signal format.

The operation of the signal processing circuit 2 having the above configuration will be described more specifically.

For example, a black line image on a document is represented by a black run length code corresponding to its length. However, if the direction of main scanning is slightly deviated from the longitudinal direction of the black line, a blank may occur while the line image transitions from the current main scanning to the next main scanning, At this time, the black run length code on each main scan has unjustly short length information. In addition, when reading an image of a black line, if there is blur in a part of this line, unevenness occurs in the image signal, and a white run length code of short length information is mixed between the black run length codes. Like Therefore, when the image boundary detection circuit 23 detects these run-length codes, if the expansion circuit 25 changes the length information of the black run-length code to a longer one, lines that are interrupted by blanks or blurring are connected. The image can be corrected at the same time. In addition, at this time, when the length information of the white run-length code becomes zero due to the shortening, the white run-length code is deleted and the black run-length codes before and after are replaced by one run-length code. Can be merged into.

Further, when a white original is scanned, black dot-like stains may occur on the image signal due to noise of the image reading device 4 or the like. When such a dot-like stain occurs, an extremely short black run length code is rarely mixed between sufficiently long white run length codes.
Therefore, when the image boundary detection circuit 23 detects these run-length codes, the contraction circuit 26 changes the length information of the white run-length code to a longer value, and the length of the black run-length code is correspondingly changed. By shortening the length information or deleting the code itself, the black dot-like stain can be removed and the image can be corrected. As in the expansion circuit 25, the white run length codes before and after can be merged into one when the black run length code is deleted.

Therefore, the signal processing circuit 2 can perform extremely useful image processing of preventing line discontinuity and blurring of the original image and removing dot-like stains, and the conventional image reading apparatus. 4 and the density adjustment in the image recording apparatus 5, it is possible to perform more delicate image adjustment.

As a result, the facsimile apparatus of the present embodiment only needs to carry out simple processing on the data-compressed image signal only in the main scanning direction of the image signal and store several run-length codes. Therefore, extremely useful image processing can be performed without requiring a complicated processing unit or a large-capacity storage device.

In the above embodiment, the image adjusting apparatus of the facsimile machine has been described, but the image processing system for performing data compression based on the run length coding method can be similarly applied to other apparatuses. is there. Further, in this embodiment, the modulation / demodulation device 1 and the signal processing circuit 2 are described as separate components, but the function of the signal processing circuit 2 may be incorporated in the modulation / demodulation device 1. The present invention can be implemented only by replacing the modulator / demodulator 1 without changing the configuration of the facsimile machine.

[0023]

As is apparent from the above description, according to the image adjusting apparatus for the image processing system of the present invention, complicated processing means and a large-capacity storage device such as a full-scale image processing apparatus can be used. It is possible to perform finer and more effective image adjustment than the conventional density adjustment by removing line blurs and dot-like stains on the image with a simple device without using.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a facsimile apparatus in which the embodiment is used.

[Explanation of symbols]

 23 image boundary detection circuit 25 expansion circuit 26 contraction circuit

Claims (1)

[Claims] 1. An image adjusting apparatus for an image processing system for processing an image signal data-compressed by a run-length encoding method, wherein an image boundary for detecting each run-length code from the image signal subjected to the data compression. An image adjusting apparatus comprising: a detecting unit; and an image boundary changing unit that relatively corrects the run length codes detected by the image boundary detecting unit.