KR930010145B1 - Picture improving method for fax - Google Patents

Abstract

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Description

How to improve the quality of normal mode received image in facsimile system

1 is a block diagram of a facsimile system.

2 is an explanatory diagram of recording of a normal mode received image.

3 is a conventional flow diagram.

4 is a diagram illustrating a normal mode received image recording in FIG.

5 is a flow chart according to the present invention.

6 is a memory map configuration diagram for image processing of the present invention.

7 is a configuration diagram of a state discrimination window for determining an image state of the present invention.

8A and 8B are exemplary views of processing according to the image state of the present invention.

9 is a diagram illustrating normal mode reception image recording according to the present invention.

The present invention relates to a method for improving the image quality of a normal mode received image in a facsimile system. In particular, the present invention relates to a method for improving the sub-scanning direction of a normal mode received image to smoothly express a curved line of an original. It is about.

1 is a block diagram of a general facsimile system, in which a central processing unit (hereinafter referred to as a CPU) 10 for controlling a system and performing various operations is scanned, and an original image is scanned by the control of the CPU 10. A document scanning unit 20 for generating a signal, converting the generated analog image signal into digital image data, and outputting the image data; and image data output from the document scanning unit 20, received image data, and dither matrix. The signal processing unit 30, which is stored in a memory and performs encoding and decoding when transmitting and receiving image data with another system, and the image data stored in the signal processing unit 30 are controlled by the CPU 10. A recording unit 40 which inputs and records on a recording sheet, and image data stored in the signal processing unit 30 is transmitted to another system through a public circuit network under the control of the CPU 10; It consists of a transmission unit 50 that receives from the system.

In general, when a facsimile system transmits and receives an image of an original in normal mode, the resolution of the image is 200 dpi (dot per inch) in the main scanning direction and 100 dpi in the sub scanning direction.

Accordingly, a facsimile system as shown in the first diagram shows a line of binarized image data received and reproduced in the sub-scanning direction as a thermal recording element (TPH: Thermal Print Head) having a resolution of 200 dpi in the recording unit 40. Similarly to the 2a diagram, the same recording is performed twice so as to be 100 dpi. In this case, the first line to be written is called an odd line Lo, and the second line to be written like this is called an even line Le.

In addition, when writing with the 2a diagram, the radix line Lo and the even line Le are the same, so the main scanning direction size W for one pixel as the 2b diagram is 1 / 8.8 mm, which is 200 dpi, and the sub scanning direction size ( T) is 1 / 3.85 mm and becomes 100 dpi.

Here, in the case of the normal mode and the fine mode reception, the main scan direction size W for one pixel is 200 dpi at 1 / 8.8 mm, but the sub scan direction size To is 200 dpi at 1 / 7.7 mm.

3 is a flowchart of conventional normal mode reception and recording.

Referring to FIGS. 1 to 3, a conventional normal mode reception and recording method will be described below.

If the facsimile system of FIG. 1 now operates in normal mode, the CPU 10 controls the transmitter 50 and the signal processor 30 in step 3a of FIG. 2 to receive and reproduce 1-line image data. do. Thereafter, in step (3b), the radix line Lo is recorded as the thermal recording element of the recording unit 40 as shown in FIG. 2a, and the even line Le is recorded in the same manner as the radix line Lo. Next, in step (3d), it is checked whether all the lines of the original have been received and written, and if not, loops to the step (3a) to repeat the above-described operation, and when it is completed, ends.

Therefore, the main scanning direction is 200dpi and the subscanning direction is 100dpi to record the received image.

At this time, the diagonal or curved portion of the original is recorded as, for example, the fourth degree.

Therefore, in the conventional normal mode receiving image recording method, the same image data is recorded twice in the sub-scanning direction, resulting in a problem that the picture or character lines of the original are not smooth and are curved, resulting in deterioration in image quality.

Accordingly, an object of the present invention is to provide a method for improving image quality in a facsimile system, which can smoothly record the curvature of an original upon reception of a normal mode.

Another object of the present invention is to provide a method for improving image quality in a facsimile system, by determining the curvature of the image state of three lines in which the normal mode received image is continuously received, and recording the odd and excellent lines differently. have.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The block diagram of the facsimile system to which the present invention is applied is the same as the above-described first diagram and the same reference numerals.

5 is a flowchart according to the present invention, which receives one line of image data, stores it in the previous line buffer, records the stored image data in the odd and even lines, and then receives the next one image data in the current line buffer. An initial recording process of storing the image data in the first line, and storing the image data of the next one line in the next line buffer and sequentially bending the image state in the state determination window for the current processing pixel with respect to the stored image data of the current line buffer. A resolution conversion process of determining the odd and even line image data for the current processing pixel according to the determination result and storing the odd and even line buffers in the odd and even line buffers respectively, and the odd number of odd line image data stored in the odd line buffer. 1 line of even line image data recorded in the line and stored in the even line buffer After the conversion recording process to record in the even line and the completion and reception of all the lines have been checked and proceeded to the resolution conversion process if not completed, the image data of the current line buffer at the same time to the base and the even line after completion End recording process is completed.

FIG. 6 is a diagram of a memory map for image processing according to the present invention. FIG. 6A is a diagram of a memory map of a line buffer of the signal processing unit 30. FIG. Previous high buffer (BF1), current line buffer (BF2), next line buffer (BF3), odd-numbered line for storing image data of resolution-converted odd number and even-numbered line of image line (BFE), odd number line It consists of a buffer (BFO).

6B is a memory map configuration diagram of the internal processing buffer of the CPU 10, wherein PA, PB, and PC are image data of each pixel of the previous column, the current column, and the next column of the previous line, respectively, PD, PE, and PF, respectively. Previous column, current column and next column of current line image data of each pixel, PG, PH, PI are image data of each column of previous column, current column and next column of next line, respectively, DET Is a determination value of a state determination window for determining an image state of an image, and TH is a value set in advance to determine image data of odd and even lines for the current processing pixel compared with the determination value DET. It is set to black "pixel value and set to" 1 ", for example.

7 is a diagram illustrating a state discrimination window for determining an image state of the present invention. When the brightness values of pixels in the i-th line (row) and j-th column of the received image data are referred to as image data (PE) of the current processing pixel, FIG. Image data of nine pixels of the previous column j-1, the current column j, and the next column j + 1 of the line i-1, the current line i, and the next line i + 1, respectively. (PA, PB, PC, PD, PE, PF, PG, PH, PI) is designated as the status determination window.

8 and 8b are diagrams illustrating processing according to the image state of the present invention, and FIG. 8a shows four cases in which image data of odd lines and even lines are differently processed with respect to the current processing pixel when there is curvature of an original. And half of the "white" pixels in "normal" mode as "black".

FIG. 8B shows eight cases in which FIG. 8A is applied according to the image state in the state determination window.

FIG. 9 is a diagram showing an example of normal mode reception image recording of the present invention, showing an example of image recording when the present invention is applied to the above-mentioned FIG. 4, showing that the curve or diagonal of the original is smoothly processed.

Hereinafter, a block diagram of FIG. 1 attached to an operation of a preferred embodiment of the present invention will be described in detail with reference to FIGS. 5 to 9.

First, when the facsimile system of FIG. 1 performs the normal mode reception operation, the CPU 10 controls the transmission unit 50 to receive image data line by line through the public line network, and reproduces the codes and the like as the signal processing unit 30. Process and store in the line buffer. In this case, the image data is data that is binarized to "black" or "white", for example, "black" is "1", and "white" is "0". The binarized image data is "black" and "white". This may be expressed in the reverse direction, but in the description of the present invention, "black" "1" and "white" are assumed to be "0".

As described above, the CPU 10 controls the transmitter 50 and the signal processor 30 in step 101 of FIG. 5 for reception and recording according to the present invention during normal mode reception. After receiving and reproducing the data, the data is stored in the previous line buffer BF1 as shown in FIG. 6A of the signal processor 30.

Since the image data of one line stored in the previous line buffer BF1 is first received and there is no previous line, the method of the present invention cannot be applied, and thus the odd and even lines are performed in steps (102) to (103) as in the prior art. Record the same in

After recording the first line as described above, in step 104, image data of the next one line is received and stored in the current line buffer BF2 as shown in the sixth diagram of the signal processor 30. FIG.

Thereafter, in step 105, image data of the next one line is received and stored in the next line buffer BF3 as shown in the sixth diagram of the signal processing unit 30. Accordingly, when all the image data of three consecutive lines is stored, in step 106, the image state of the current processing pixel is determined by using the image data of the second pixel among the stored image data of the current line buffer BF2 as the current processing pixel. Specifies a state determination window equal to the seventh degree for.

Next, in step (107), the nine image data (PA-PI) specified in the state determination window are stored in the same processing buffer as the internal sixth diagram, and in step 108, the following equation is calculated to calculate the state determination value (DET). Is obtained and stored in the processing buffer as shown in FIG.

Equation (1) is based on eight cases as shown in FIG. 8B (a)-(h) for smoothly discriminating the curved or oblique portions of the original as follows.

First, the truth table for recording the radix line Lo and the even line Le differently in the eight cases of FIGS. 8B (a)-(h) in the same manner as in FIGS. 8A (a)-(d) is as follows. Same as the table.

TABLE 1

In the table (1), "1" is image data of "black" pixels corresponding to portions hatched in FIGS. 8A and 8B, and "0" is image of "white" pixels corresponding to portions not hatched. Data. &Quot; X " represents a don't care pixel, and NO1-NO8 in Table 1 correspond to (a)-(h) in Fig. 8B, respectively.

In the table (1), the image data of the radix line Lo is the same as the image data PB of the current column pixel of the previous line, and the image data of the even line Le is the image data PH of the current column pixel of the next line. We can see that

If the current processing pixel, which is the current column pixel of the current line, is not taken into consideration, it is reduced to four cases of NO1 and NO2, NO3 and NO4, NO5 and NO6, NO7 and NO8.

Therefore, in the formula (1), (PB, PC, PD) NO1 and NO2 in Table (1), (PA, PB, PF) In Table (1), NO3 and NO4, (PD, PH, PI) Are NO5 and NO6 in Table (1), (PF, PG, PH) Becomes NO7 and NO8 of Table (1).

Therefore, in the above Equation (1) and Table (1), the image data of the odd line and the image data of the even line are expressed by the following equation.

In step (108), the determination value DET calculated by the above equation (1) is set to a pixel value of "black" in advance in the internal processing buffer of the CPU 6, such as the 6th degree of the CPU 10, in step 109. Compare the set value (TH) with "1". In other words, it is determined whether or not the curvature corresponds to one of the curvatures corresponding to one of the eighth times in the reception image state determination window, i.e., "1" if there is a curve or oblique line and "0" if there is no curvature.

At this time, if the state determination value DET becomes "1" and there is curvature, steps (110) to (111) to record the odd line Lo and the even line Le differently for the current processing pixel as shown in FIG. 8B. The image data PB of the previous line current column pixel and the image data PH of the next line current column pixel as shown in the equations (2) and (3), respectively, are stored in the radix line buffer BFO of FIG. ) And even line buffer (BFE) respectively.

If the state determination value DET becomes "0" and there is no bending, the image data PE of the current processing pixel is stored in the odd line buffer BFO and the even line buffer BFE in step 112 as it is. .

As described above, after determining and storing image data of odd and even lines for one current processing pixel, it is checked whether all the pixels of the current line buffer BF2 have been processed in step 113 and have not been processed. In step 114, the state determination window is moved to the next pixel, stored, and then looped to step 107 to repeat the above process to process all pixels.

When the processing for all the pixels is completed, in step 115, the same number of odd-numbered line buffers BFO and BFE and even-numbered line image data of the same process and stored in FIG. 6A are sequentially recorded as the recording unit 40. FIG.

In order to process the next line, the image data of the current line buffer BF2 of FIG. 6A is moved to the previous line buffer BF1 and stored in steps 117 to 118, and the image data of the next line buffer BF3 is stored. After storing in the current line buffer BF2, it is checked whether all lines have been received and written in step 119. If the previous line reception and recording is not completed in step (119), the loop is looped to step (105) to process all the lines by repeating the above-described process, and if the current line buffer is completed in steps (120) to (121). The image data of (BF2) is equally recorded in the last radix and even line of the original and ends.

If the next page of the original is received, the above-described process is repeated.

When the present invention as described above is applied to the bent portion in FIG. 4 by the conventional reception and recording method described above, it can be seen that the image quality is improved by smoothly expressing the ninth degree.

As described above, in the facsimile system, the image quality of the curved portion of the document can be discriminated and recorded smoothly in the normal mode.

Claims (4)

In a method for improving the quality of a normal mode received image in a facsimile system, the image data of one line is received, stored in the previous line buffer, the stored image data is recorded in the odd and even lines, and the next one image data is received. An initial recording process of storing the current line buffer, and receiving the image data of the next one line and storing the image data of the next one line into the next line buffer and sequentially storing the image data of the current line buffer with respect to the stored image data of the current line buffer. A resolution conversion process of determining whether the curvature of the curvature is correct and storing the image data of the odd and even lines for the current processing pixel and storing the image data of the odd and even lines in the odd and even line buffers, respectively. Image data is written to the nose line and stored in the even line buffer The conversion recording process of recording one line of even-line image data on the even line, and checking whether or not all lines have been received and completed, proceeds to the above resolution conversion process, and when the completion completes the image data of the current line buffer. And an end recording process of terminating and then recording the same on the even line. The method of claim 1, wherein the state determination window of the resolution conversion process comprises: image data (PA, PB, PC) of each pixel of the previous column, the current column, and the next column of the previous line and the previous of the current line with respect to the current processing pixel; Characterized by specifying image data (PD, PE, PF) of each pixel in the column, the current column, and the next column, and image data (PG, PH, PI) of each pixel in the next column, the previous column, the current column, and the next column. How to improve image quality. 3. The method of claim 2, wherein the resolution conversion process comprises: receiving a first line of image data and storing the image data in a next line buffer; and a second step of designating the state determination window for a current position pixel of a current line buffer. And a third step of storing the state determination window designated image data (PA, PB, PC, PD, PE, PF, PG, PH, PI) from the previous line buffer, the current line buffer, and the next line buffer to the processing buffer, respectively. And a state discrimination value for determining the presence or absence of an image state in the state discrimination window by calculating the following equation with respect to the specified image data PA, PB, PC, PD, PE, PF, PG, PH, and PI. The fourth step of obtaining DET), When the state determination value DBT of the fourth step is equal to the preset value TH, the image data PB of the previous line current column pixel is used as the odd line image data of the current processing pixel. When the data is stored in the odd-numbered line buffer, the fifth step of storing the image data PH of the next line current row pixel as the even-line image data in the even-line buffer, and the state determination value DET of the fourth step is the set value ( And the sixth step of storing the image data PE of the current processing pixel as the odd and even line image data for the current processing pixel in the odd and even line buffers, respectively, as determined by the non-curved portion. Examine whether buffer processing is complete in the buffer, and when it is completed, proceed to the above conversion recording process. And a seventh step of moving the window to the third step. 4. The image quality improving method according to claim 3, wherein the preset setting value (TH) of said fourth and fifth steps is set to the same value as image data for " black " pixels.