JPH0918719A - Decoder and facsimile equipment with same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily conduct processing of decoding coded data and storing decoded data to a storage section as image data in a short period of time. SOLUTION: Coded image data are subjected to black/white level run length decoding and the result is stored in an image buffer 7 as image data. In this case, all data in a prescribed area of the image buffer 7 to which decoded data are to be written are rewritten into white level data in advance by a DMA controller 9 prior to decoding. When the coded data are decoded and the decoded data are black run length data, the data are sequentially written in a prescribed area of the image buffer 7 corresponding to the address. When the decoded data are white run length data on the other hand, the address of the prescribed area of the image buffer 7 is advanced by the address corresponding to the run length.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decoding device that decodes encoded image data into black and white run lengths and stores it as image data in a storage unit, and a facsimile apparatus including the decoding device.

[0002]

2. Description of the Related Art In a facsimile machine, image data is transmitted in a state in which it is encoded by an encoding method such as a modified Huffman method (MH method), a modified read method (MR method), or a modified MR method (MMR method) Is coming. Therefore, it is necessary to decode the received encoded data before printing. in this case,
After decoding the encoded data into black and white run lengths and storing at least one line in the image buffer as image data, the image data is transferred to the recording unit for each line and printed. .

[0003]

However, in addition to the process of decoding encoded data into black and white run lengths, the process of expanding the decoded data into image data and storing it in the image buffer is also very cumbersome and time-consuming. It is such a thing. That is, in order to expand the data decoded into the black and white run length into the image data and store it in the image buffer, the troublesome process of sequentially writing the decoded data bit by bit as a bit image while designating an address in the image buffer. Should be done
A lot of time was spent on the writing process. Moreover, the process of sequentially writing the decoded data as a bit image bit by bit occupies a large weight in the entire decoding process.

[0004] The present invention has been made by focusing on such problems existing in the prior art. It is therefore an object of the present invention to provide a decoding device and a facsimile device including the decoding device, which can easily and quickly perform a process of decoding encoded data and storing it as image data in a storage unit.

[0005]

In order to achieve the above object, in the invention of the decoding device according to claim 1, rewriting means for rewriting the predetermined area of the storage unit to white data before decoding, When the decoded data is a white run, the address of the predetermined area is advanced by an amount corresponding to the run length, and when the decoded data is a black run, a control means for writing black corresponding to the predetermined address is provided. Is.

According to a second aspect of the present invention, in the decoding device according to the first aspect, the rewriting means is a DMA controller for sequentially DMA-transferring white data while designating an address to the storage section.

According to a third aspect of the present invention, in the facsimile apparatus provided with the decoding device according to the first or second aspect, the storage unit transfers an image to a recording unit for printing on a recording sheet. An image buffer that stores at least one line of data.

Therefore, in the decoding device according to the first aspect, all the data in the predetermined area of the storage unit is rewritten to white data before decoding the encoded data, and then the encoded data is black and white run length. Will be decrypted. At this time, when the decoded data is a black run, the data is sequentially written as a bit image corresponding to an address in a predetermined area of the storage unit. On the other hand, when the decoded data is a white run, the address of the predetermined area of the storage unit is advanced by an amount corresponding to the run length, in other words, the number of consecutive white pixels, and the writing process of the decoded data is performed. Is not done. That is, all the data in the predetermined area of the storage unit to which the decrypted data should be written are rewritten to white data in advance prior to the decryption. Therefore, with respect to the decrypted data of the white run, the write process is not performed and the address is simply advanced. The same result as that written in the memory can be obtained. White data is overwhelmingly larger than black data in normal image data. Moreover,
The process of rewriting all the data in the predetermined area of the storage unit to the white data can be performed in a shorter time than the process of sequentially writing the decoded data as a bit image bit by bit. Therefore, not performing the writing process of the white data, which occupies most of the image data, is effective in reducing the time required for the entire decoding process.

In the decoding device according to the second aspect, the process of rewriting the data in the storage unit into the white data is performed at high speed by the DMA controller, and the time required for the entire decoding process is further shortened.

In the facsimile apparatus according to the third aspect, the received coded data is decoded in a short time and stored in the image buffer as image data, so that the received image data can be printed out smoothly and quickly.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration of the facsimile apparatus according to this embodiment. A CPU (Central Processing Unit) 1 is a ROM (Read Only Memory) that stores programs for controlling the operation of the entire device.
2, and a RAM (random access memory) 3 for temporarily storing various information is connected. In this embodiment, the CPU 1, the ROM 2 and the RAM 3 constitute the control means. When the encoded image data is received, the CPU 1 decodes the received image data into black and white run length based on the program stored in the ROM 2.

The NCU (network control unit) 4 has a function of controlling the connection with the telephone line and detecting the sending and receiving of dial pulses corresponding to the fax number of the other party. The modem 5 performs modulation and demodulation of transmitted / received data. The reading unit 6 optically reads an image on a document set on a document table (not shown).

The image buffer 7 as a storage unit is C
The image data decoded into the run length by the PU 1 is stored as image data. As shown in FIG. 4, the image buffer 7 has two line memories 7a and 7b for respectively storing image data (line data) for one line bit by bit corresponding to an address. The recording unit 8 as a recording unit prints one line on a recording paper based on the image data stored in the image buffer 7.

A DMA (direct memory access) controller 9 as a rewriting means DMA-transfers white pixel data to the image buffer 7 based on a start command from the CPU 1. The white pixel data transferred to the image buffer 7 is previously stored in the ROM 2, for example. The address counter 10 uses the image buffer 7
Manages the address of. That is, the address counter 10 designates the address of each line memory 7a, 7b in the image buffer 7 based on a command from the CPU 1 or the DMA controller 9.

Next, the operation at the time of reception of the facsimile apparatus configured as described above will be described with reference to the flow charts shown in FIGS. 2 and 3 and FIG. 2 shows the processing executed by the CPU 1, and FIG. 3 shows the DMA.
The process performed by the controller 9 is shown.

As shown in FIG. 2, the MH system,
When image data encoded by the MR system or the MMR system is transmitted and the image data is received,
The CPU 1 issues a start command to the DMA controller 9 (steps S1 and S2). On the other hand, as shown in FIG. 3, when the DMA controller 9 receives the activation command from the CPU 1, the line memory 7 a, 7 of either one of the image buffers 7 is received.
For b, the white pixel data is sequentially DMA-transferred while the address is specified by the address counter 10 (steps S21 to S22), and the process is temporarily terminated. As a result, all the data in the one line memories 7a and 7b of the image buffer 7 are rewritten into white pixel data.

Returning to FIG. 2, when the CPU 1 confirms that the rewriting process of the white pixel data by the DMA controller 9 is completed (step S3), the RTC signal (control return signal) and the EOL signal are included in the received encoded data. It is determined whether or not a signal (line end signal) is detected (steps S4 to S5). The EOL signal is added to the end of each line data of the received image data.
The RTC signal is made up of 6 consecutive EOL signals, and is added to the end of the last line of the received image data for one page of the document. CPU1 uses RTC signal and EOL
If none of the signals is detected, the received encoded data is decoded into black and white run length (step S
6).

Next, the CPU 1 determines whether the decoded data is white run length (step S).
7) In the case of the white run length, the run length, in other words, the address of one of the line memories 7a and 7b of the image buffer 7 on which the rewriting processing has been performed, corresponding to the number of consecutive white pixel data. (Step S
8). If the decoded data is the black run length, the CPU 1 sequentially writes the black run length data in the one line memories 7a and 7b as a bit image corresponding to the address bit by bit (step S9). . That is, the CPU 1 uses one line memory 7
For the a and 7b, the black pixel data is sequentially transferred by the amount corresponding to the run length while the address is specified by the address counter 10.

The processing in steps S8 and S9 will be described in detail with reference to FIG. FIG. 4 schematically shows the image buffer 7, and here it is assumed that the decoded data is stored in one of the line memories 7a. For example, if the decoded data of "3" is black run length and the write start address is "2", three black pixel data are stored in the line memory 7a corresponding to the addresses "2-4". Written. Next, when the decoded data is the white run length of "4", the address is simply advanced by four from "5" to "8", and the writing processing of the white pixel data is not performed. Then, the address where the next black run length starts to be written is "9". Thereafter, similarly, for the white run length, the address of the line memory 7a is advanced by the run length, and for the black run length, the data is written bit by bit in correspondence with the address of the line memory 7a.

Then, the CPU 1 repeats the processing of steps S4 to S9, and when it detects the EOL signal in step S5, it judges that the reception and decoding processing of the data for one line is completed. After that, the CPU 1 transfers the image data for one line stored in one of the line memories 7a and 7b to the recording unit 8 and prints for one line (step S10). Thereafter, the CPU 1 returns to step S2 and repeats the processing of steps S2 to S10 so as to shift to the reception and decoding processing of the next line data.

At this time, the rewriting and storing processes for the line memories 7a and 7b of the image buffer 7 are alternately performed. Therefore, when printing is being performed based on the line data stored in one of the two line memories 7a and 7b, it is possible to immediately shift to the rewriting and storage processing for the other without waiting for the end of the printing. As a result, the received data can be decoded and printed smoothly and quickly.

On the other hand, when the CPU 1 detects the RTC signal in step S4, it determines that the reception and decoding processing for one page of the original document has been completed. And CPU1
Causes the final line of data for one page to be printed (step S11). Next, the CPU 1 determines whether there is received image data for the next page (step S1).
2) If there is data for the next page, the process returns to step S2 to repeat the processes of steps S2 to S12,
If there is no data for the next page, the entire process ends.

The facsimile apparatus of this embodiment having the above-described structure has the following advantages. When the received encoded data is decoded and stored in the image buffer 7, all the data in the predetermined area of the image buffer 7 in which the decoded data should be written are rewritten in advance to white data before decoding. Therefore, when the encoded data is decoded into a black and white run length and the decoded data is a black run length, the data is converted into the image buffer 7.
It is necessary to sequentially write the data in the predetermined area in accordance with the address. However, in the case of the white run length, by simply advancing the address of the predetermined area of the image buffer 7 without performing the writing process, the same result as that of writing the white run data in the image buffer 7 can be obtained. .

In the image data obtained by reading a normal original document in which characters and the like are written, white data is overwhelmingly larger than black data. Moreover, the process of rewriting all the data in the predetermined area of the image buffer 7 into the white data can be performed in a shorter time than the process of sequentially writing the decoded data as a bit image bit by bit. Therefore, when the decoded data is stored in the image buffer 7, the writing process of the white data, which occupies most of the image data, is not performed. In the present embodiment, the time required for the entire decoding process is significantly reduced. be able to. As a result, the received image data can be quickly decoded and stored in the image buffer 7, and the subsequent printing process can be performed smoothly and quickly.

Moreover, since the work amount of the CPU 1 is reduced because the white data writing process is not performed, the load on the CPU 1 during the decoding process can be reduced. for that reason,
The decoding process can be performed in a sufficiently short time without using an expensive CPU 1 that can perform high-speed processing, and the manufacturing cost of the device can be reduced. or,
On the contrary, it is possible to cause the CPU 1 to perform other processing in parallel as much as the work amount is reduced.

Further, the process of rewriting the data in the image buffer 7 into the white data is performed at high speed by the DMA controller 9 not by the CPU 1. Therefore, the time required for the entire decoding process can be further shortened and the load on the CPU 1 can be reduced.

The present invention can be modified and embodied as follows. (1) 1 line memory is used as the image buffer 7.
Must have only books or three or more books.

(2) In the two line memories 7a and 7b of the image buffer 7, while the decoded data storage processing for one is being performed, the rewriting processing for white data for the other is performed in parallel. thing. By doing this, the storage process of the decoded data can be started without waiting for the end of the rewriting process to the white data,
The time required for the entire decoding process can be further shortened.

(3) The received image data is temporarily stored in the image memory in an encoded state, and after the reception is completed, the encoded data in the image memory is read while being decoded and stored in the image buffer 7.

(4) In the above (3), when the image data is received, the number of black and white change points in each line data of the received image data is detected, and when the number of change points is equal to or more than a predetermined number, , It is determined that the received image data has been subjected to halftone processing. When it is determined that the halftone processing has been performed, when the encoded data in the image memory is decoded into run lengths, data of any black and white run lengths are sequentially written into the image buffer 7. thing. Also, in each line data of the received image data, the same processing should be performed even when the number of black pixels is a predetermined number or more. That is, when the ratio of black data to white data in the image data is high, the time required to write the black data becomes long, and conversely, the processing time may become long. Therefore, if the processing method is switched according to the received image data, such an adverse effect can be eliminated.

(5) The present invention may be applied to the case where encoded data stored in a storage medium such as a CD-ROM is decoded and transferred to a printer. (6) Instead of the DMA controller 9, a dedicated hardware circuit for rewriting all data in a predetermined area of the image buffer 7 into white data is provided.

The technical idea that can be understood from the above-described embodiment will be described below. (1) In claim 3, the image buffer has two line memories for respectively storing line data,
Storing processing of decoded data in one line memory,
A facsimile machine in which the other line memory is rewritten to white data in parallel.

By doing so, the time required for the entire decoding process can be further shortened.

[0034]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects. According to the first aspect of the invention, the process of decoding the encoded data and storing it as image data in the storage unit can be performed easily and in a short time.

According to the second aspect of the invention, the process of rewriting the data in the storage unit into the white data can be performed at high speed by the DMA controller, and the time required for the entire decoding process can be further shortened.

According to the third aspect of the present invention, since the received encoded data is decoded in a short time and stored in the image buffer as image data, the received image data can be printed out smoothly and quickly.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a facsimile apparatus showing an embodiment of the invention.

FIG. 2 is a flowchart showing a reception process executed by a CPU.

FIG. 3 is a flowchart showing processing of a DMA controller.

FIG. 4 is an explanatory diagram schematically showing an image buffer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CPU which comprises a control means, 2 ... ROM which comprises a control means, 3 ... RAM which comprises a control means, 7 ... Image buffer as a memory | storage part, 7a, 7b ... Line memory, 9 ... DMA as a rewriting means Controller, 10 ...
Address counter.

Claims (3)

[Claims] 1. A decoding device for decoding encoded image data into black and white run lengths and storing the image data in a storage unit as image data, and a rewriting unit for rewriting white data in a predetermined area of the storage unit prior to decoding, When the decoded data is a white run, the address of the predetermined area is advanced by an amount corresponding to the run length, and when the decoded data is a black run, the decoding is provided with a control means for writing black corresponding to the predetermined address. apparatus. 2. The rewriting unit sequentially DMA-transfers white data while designating an address to a storage unit.
The decoding device according to claim 1, which is a controller. 3. The decoding device according to claim 1, wherein the storage unit is an image buffer that stores at least one line of image data to be transferred to a recording unit for printing on recording paper. Facsimile equipment equipped.