KR910006682B1 - Image data curve detecting method for picture transmission device - Google Patents

Abstract

The method detects the inflection of the image data using the bit detection table and the mask table. The method includes steps: (A) comparing the detected inflection bit address and the number of bit of the standard pixel of one line; (B) replacing the value of the inflection bit position by the number of pixel when the bit address is larger; (C) checking that the inflection exists on one byte of the scan data whent eh bit address is smaller; (D) calculating the inflection bit address when the inflection exists on one byte of the scan data and otherwise increasing the memory address of the scan buffer; (E) checking that the scan buffer address is the last address of the line; and (F) writing the end of the line on the address saving region of the scan buffer when the scan buffer address is the last address, loading the number of pixel on the inflection bit, and oterwise saving the address of scan buffer memory and calculating the inflection bit address.

Description

Image data inflection point detection method of image transmission device

1 is a block diagram of a portion of an image transmitting apparatus for carrying out the present invention.

2 is a memory map of a scan buffer of FIG.

3 is a block diagram of an image data inflection point detection flowchart according to the present invention.

4 is a bit decoder memory table according to the present invention.

5 is a mask table according to the present invention.

6 is a detailed flowchart of the FIG. 3 flow chart.

The present invention relates to a method for detecting an image data inflection point of an image transmission device. Currently, there are many image transfer apparatuses, but a typical one thereof is a facsimile (hereinafter referred to as FAX) for transmitting an image of a document.

As described above, all documents to be transmitted by FAX (Document: hereinafter called DOC) are scanned for each line of the size specified in CCITT T.4 and logically compressed to reduce the number of bits of data to be transmitted. It is sent after execution.

The scanned and logicalized FAX image data is divided into black and white, and the unit separated as described above is called a pixel.

One pixel is 1 / 7.7 mm long and 1/8 mm wide. The size may vary with system resolution.

For example, when scanning an A4 size document, the number of pixels per line becomes 1728. The Cosing Method is also recommended in CCITT Regulation T.4. MH (Modified Huffman Code) and MR (Modified Read Code) methods are mainly used.

The MHting is a method of coding one line, that is, the number of consecutive pixels of a black pixel or a white pixel among 1728 pixels, line by line according to a code table.

For example, if three consecutive white hydrogens or ten black pixels are consecutively scanned, the scanned data (pixel data) consists of a code corresponding to white pixel number 3 and a code corresponding to 10 black decimal points. .

In order to obtain the same number of pixels of consecutive same color of scan data in the MH coding process as described above, a color conversion point (Change Point: hereinafter) in which scan data is a logic 0 of a white pixel and a logic "1" of a black pixel or the opposite thereof The inflection point). MR coding is also a method of coding a current line by leaving a reference line.

In the MR coding, a reference line refers to a previous line where a previous coding has been completed, a line which is located immediately below a current line, and refers to a line to be currently coded.

In order to code the current line as described above, the coding may be performed by comparing the distance between the inflection points only by obtaining the inflection points of the reference line and the current line.

Therefore, in the case of the MH coding or MR coding, detection of the inflection point must be performed. Accordingly, an object of the present invention is to provide a method for dedicating an inflection point required when coding image data in an image transmission device for coding and transmitting image data.

Another object of the present invention is to provide a method of detecting an inflection point of image data using a bit decrement table and a mask table.

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

1 is a block diagram of a portion of a FAX for carrying out the present invention, in which the MPU is a microprocessor, the DMA is a direct memory access DOC, the document CCD is a charge coupled device, and the LES is Level Slicer, SR is Shift Register and SBM is Scan Buffer Memory.

The above structure is constituted in all the FAX, and the photoelectric conversion element CCD receives the photo from the original DOC and photoelectrically converts the original photoelectrically by the main scanning. The photoelectric conversion signal is digitally leveled by level slicer LES. The converted logic data is converted. The digitized data in the level slicer LES is input to the shift register SR.

The data converted in parallel by the operation of the shift register SR are sequentially stored in the scan buffer memory SBM by the direct memory access DMA under the control of the microprocessor MPU. As described above, the scan data saved in the scan buffer memory SBM, i.e., 8 bits of pixel data, is saved in units of pixels. In this case, the memory mapping of the scan buffer memory SBM is shown in FIG. 2.

FIG. 2 (A) shows the byte address status of the scan buffer, which is 100H bytes per scan line. At this time, the line is 100H bytes because the pixel number is 256 bytes when scanning A4 paper, even when scanning 216 bytes B4 paper.

2B shows a pixel bit address for designating each of the 8 bit pixel data in the byte address of the scan buffer. When scanning an A4 document (document) DOC, there are 1728 pixels in one line, so it is 000H-00D7H for the byte address and 06COH for the bit address. When scanning the B4 document DOC, the byte address is 0000H-00FFH and the bit address is 0800H because the number of pixels per line is 2048.

3 is a software block as an inflection detection flow diagram according to the present invention.

4 is a bit de-diction table for detecting an inflection point according to the present invention, which is arbitrary in an address region up to 00H-FFH (256 bytes) that can be represented as one byte to detect an inflection point in pixel data within one byte. When the corresponding number of is defined as an index, the pixel inflection point bit position in one byte of pixels is defined.

The bit detection table (hereinafter referred to as BITDET) is to calculate the number of consecutive logical 0s from the MSB (highest bit of one byte), and the numbers from addresses 00H to FFH are indexes. Is a table created so that the number of consecutive zeros becomes the data of the memory location whose index is Index1.

5 is a mask table according to the present invention, which detects an inflection point located in pixel data within one byte and then masks the pixel bit data where the inflection point is detected when detecting an inflection point that can be located in the same byte. . The above table also uses the index Index1 to fetch and use the data corresponding to the index.

6 is a detailed flowchart of FIG. 3 according to the present invention. Before describing the operation example of the present invention with reference to FIGS. 1 to 6, it is assumed that the document DOC size of FIG. 1 is A4. When the document DOC is inserted into the document insertion port of the FAX in the circuit as shown in FIG. 1, it is sequentially saved in the predetermined byte address area of the scan buffer memory SBM as shown in FIG.

As described above, when the inflection detection flow is RUN in the state where the scan data is stored in the scan buffer memory SBM, the microprocessor MPU performs the inflection point bit address and one line of the inflection point detected so far in FIG. It is determined whether the number of prescribed pixel bits is smaller than the number of prescribed pixel bits by comparison with the number of prescribed pixel bits.

For example, if the pixel bit data of the bit address 0000H in the byte address 0000H, which is the initial start address of the scan buffer memory SBM in FIG. 2, is accessed, it is less than the A4 original one-line pixel bit number 1728. Clear the work register in the processor MPU.

At this time, the work register is composed of two bytes, the upper and lower bytes can be used separately, four RA, RB, RC, RD is embedded in the microprocessor. The microprocessor MPU performing step (6b) registers the result of exclusively ORing the byte address (SBMA) of the current scan buffer memory of the scan buffer memory (SBM) and the pixel comparison data COMDAT of a predetermined value in step (6c). Save to RBL.

In this case, the pixel comparison data COMDAT is a value initialized to 00H at the time of performing the first inflection point detection of one line, which is converted every time the routine of the present invention is performed.

The register RBL represents the lower byte of the work register RB. Therefore, when the pixel data of the initial byte address 0000H of the scan buffer memory SBM is "00011100" as shown in FIG. 2, the data stored in the register RBL is "00011100". This is because the byte address 0000H of the scan buffer memory SBM is saved as it is 00H compared with the initial pixel.

The microprocessor MPU performing step (6c) accesses the mask table value of FIG. 4 using the data in the index register (Index1) of the mask table (hereinafter referred to as Maskble) in step (6d).

At this time, the index Index1 is a register for accessing a specific value of the mask table Maskble and is initialized to 00H during the initial operation.

Therefore, the microprocessor MPU accesses the data " 111111111 " of address 00H of the mask table of FIG. 5 by the value of the internal index register Index1 in AND, and logically ANDs the data stored in the register RBL. Save to register RBL. Thereafter, the microprocessor MPU searches whether the data of the register RBL is all "0" in step 6e to check whether there is an inflection point data within the scanned byte.

If the result of the search is not "0", the current save data of the register RBL is saved in the index register Index2 in step 6l, and the data saved in the index Index2 in step 6l is stored in the bit decode table address. By accessing the data of the bit decode table, the resulting data is loaded into the internal register (RAL) in 6m. That is, in step 6m, data of 03H is accessed from the bit decode table of FIG. 4 with the address "00011100" of the register RBL described above as an address, and the access data is stored in the register RAL. Subsequently, in order to use the contents saved in the register RAL by the 6m process as the address index of the next mask table, the data 03H of the register RAL is stored in the index Index1 in the 6n process.

In step 6o, the microprocessor (MPU) stores the 16-bit address SBMA of the current scan buffer memory (SBM) in the internal register RC. The microprocessor (mpu) performing step 6o saves the address of the lower register RCL of the internal register RC, that is, the lower address of the scan buffer memory (SBM), to the lower register RDL of the register RD in step 6p, and the scan buffer in step 6r. Bit addressing is performed by shifting the lower two bytes of the memory SBM address three times to the left.

The microprocessor MPU performing step 6r has an inflection point position in the contents of the lower register RDL of the bit addressed register RD in step 6s and the byte address of the scan buffer memory SBM detected by step 6m. The data 03H is added to calculate the inflection bit address, and the result is loaded into the register RDL.

The microprocessor (MPU) that calculates the inflection bit address in the byte address of the scan buffer memory SBM registers the inflection point bit address stored in the register RD in 6t to store the inflection bit address return value (Return Value). Load it into CPRV) and compament the comparison data COMDAT in step 6u. The reason why the comparison data COMDAT is completed is to find the inflection point after the inflection point is depressed once.

If the data of the register RBL is all "0" in the above-described process 6e, it is determined that there is no inflection point in the data of the address area of the currently accessed scan buffer memory (SBM), and in step 6f the scan-buffer memory (SBM) Increment the address of (Incrementing). After increasing the address of the scan buffer memory (SBM), the microprocessor (MPU) subtracts the current scan buffer memory address (SBMA) from the start scan buffer address (SBMAO) of line-by-line scan data. TBC) is searched in 6g.

In this case, the number of byte pixels TBL for each document DOC size is 216 bytes in A4 and 256 bytes in B4.

If it is not the same as the search result of step 6g, in step 6h, the data of the current scan buffer memory address (SBMA) area is compared with the comparison data COMDAT in which all bits have the same logic to search for an inflection point. If the pixel data of the current scan byte has the same logic as that of the comparison data and the inflection point is repeated, the aforementioned step 6f is repeated. If the inflection point is detected, the current scan buffer memory address SBMA is assigned to the predetermined buffer in step 6i. Save to (CPBASA). In this case, the buffer CPBASA is an address of an area for saving a scan buffer address having an inflection point.

In operation 6j, the microprocessor (MPU) updates a predetermined buffer CPBASA to save the next scan buffer memory address in operation 6j. The microprocessor MPU which has executed the update in step 6j exclusively ORs the scan data specified by the comparison data COMDAT and the current scan buffer memory address (SBMA) in step 6k, loads the result into the register RBL, and performs the above-described step 6l. The inflection point bit address in the current scan buffer memory (SBM) byte is calculated as described above.

Therefore, in the above-described processes 6i, 6j, and 6k, it can be seen that the address of the scan buffer memory having the inflection point is stored in a predetermined buffer and used for MR coding when the inflection point of the current line is detected.

On the other hand, if the comparison result in the above 6g process is the same, the microprocessor (MPU) saves the data indicating the line end (Line End) in the CPBASA in the scan buffer memory address save area where the inflection point exists in 6w process.

The microprocessor MPU performing the 6w process loads the line end bit address into the inflection point bit address (CPRV). For example, if the document DOC is A4, 06COH is loaded in 6x.

As described above, the present invention can easily compress the FAX image data by accurately scanning the inflection point of the scan data with the data of the bit deduction table and the mask table and simple software.

Claims (1)

An image data inflection point detection method of an image transmission device, comprising: a first step of comparing whether an inflection point bit address detected so far and the number of prescribed pixel bits of a line are searched to determine whether the current inflection point bit address is less than a prescribed number of pixel bits; A second step of loading a value corresponding to the number of pixels at an inflection point bit position and repairing the comparison data when the search result of the first step is larger than a prescribed pixel; and when the search result of the first step is smaller than a prescribed pixel A third step of searching for whether there is an inflection point in one byte of the scan data, and calculating the inflection point bit address in one byte of the scan data and repairing the comparison data when the inflection point exists in the third step. A fourth step of increasing the memory address; and after the increase of the scan buffer address, the scan buffer address is the end of line address. In the fifth step of searching for the value and the result of the search in the fifth step, the end of the line is displayed in the scan buffer memory address save area where the inflection point exists, and the value corresponding to the number of pixels is loaded at the inflection point bit position. The sixth step of repairing data and the search result of the inflection point in one byte of the scan data when the search result in the fifth step is not at the end of the line are performed to save and scan the address of the scan buffer memory in which the inflection point exists. A seventh step of repairing the comparison data by calculating the inflection point bit address in the byte and an eighth step of increasing the scan buffer memory address when there is no inflection point in the scan result scan data in the sixth step. Way.

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