JP3127029B2 - Image information encoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image information encoding device for compressing image information.

[0002]

2. Description of the Related Art MH (Modified Huffman), MR (Modified Relative Ele) are preferred encoding methods for data compression of image information.
The well-known MMT (Modified Address) or MMR (Modified MR) method is well known.

In the facsimile apparatus, when encoding image information, an EOL code indicating the end of a line is inserted for each line of image information in accordance with the recommendation of CCITT.
In the case of the MR system or the MMR system, a tag bit indicating whether the code is a one-dimensional code or a two-dimensional code is inserted together with the EOL code.

On the other hand, in an image filing apparatus which does not need to follow the recommendation of CCITT, various data are not inserted into the image information of each line according to a manufacturer's own setting. For example, if the EOL code is not inserted to reduce the data amount of the encoded data, or if the encoded data exceeds the data amount of the raw image information before encoding, instead of the encoded data, , An identification code indicating that it is raw and raw image information are set.

In general, when image information is encoded by the above-mentioned various encoding methods, various codes are stored in a table memory, and the corresponding codes are read out one by one while sequentially checking the image information. As a result, encoded data is obtained.

When encoding of one line is completed,
Various data as described above are inserted as needed.
For example, when inserting certain data such as an EOL code, the EOL code is stored in a table memory in advance, and the EOL code is read out when encoding of one line is completed.

[0007]

As described above, conventionally, the data to be inserted into the coded image information of each line is fixedly set in advance, for example, stored in a table memory. Therefore, if one encoding means tries to insert various data arbitrarily according to the usage conditions at that time, the data must be stored in the table memory, and the table memory has a large capacity. There was a problem that would be.

An object of the present invention is to provide an image information encoding apparatus capable of solving the above-mentioned problem and inserting arbitrary data between encoded data lines without increasing the capacity of a table memory. Aim.

[0009]

For this purpose, the present invention provides a method in which a black-and-white image and a run length detected from input image information are input to a code table, control data is extracted from the code table, and the control data is extracted from the code table. The control data is input to the code generation means to obtain predetermined encoded data. On the other hand, in the case where constant data is inserted between lines of encoded data, every time one line of encoded data is output, Specific control data is input to the code generation means, and the code generation means outputs certain data.

[0010]

By changing the control data input to the code generation means, arbitrary data can be inserted between lines of encoded data. In this case, the table memory does not need to store data for generating the constant data to be inserted, so that the table memory does not have a large capacity.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an image information encoding apparatus for encoding image information in the MH system according to an embodiment of the present invention. In the figure, a run length detecting section 1 detects a run length of binary image information which is sequentially input one pixel at a time, and outputs white / black and a run length.

The code table 2 is composed of, for example, a ROM, and stores each word data for generating an MH code, as shown in FIG. Each word data is composed of code data of a maximum of 8 bits and control data of 4 bits. Note that the bits marked with “x”
This indicates that “1” or “0” may be used. The word data is classified into three types: a terminating code, a standard makeup code, and an extended makeup code.

The word data for the terminating code is stored for run lengths 0 to 63 for black and white, respectively. For the standard make-up code, run lengths 64 to 1728 are stored for black and white in steps of 64, respectively. Also, for the extended makeup code, 12560 in steps of run length 1792 to 64
Up to this, data common to black and white is stored. Note that the standard makeup code is a code corresponding to an image up to A4 width, and the extended makeup code is a code corresponding to an image exceeding A4 width.

The code selecting section 3 selects one of the three types of word data when reading data from the code table 2.

The host control unit microcomputer 4 monitors and controls the entire encoding apparatus. The selector 5 selectively inputs code data from the data bus of the host control unit microcomputer 4 or the code table 2. The selector 6 is for selectively inputting control data from the data bus or the code table 2.

The shift register 7 converts code data output as a parallel signal from the selector 5 into a serial signal and outputs it. The counter 8 sets the control data output from the selector 6 as an initial value,
The counting operation is performed until the overflow from the initial value.

The AND circuit 9 outputs the output data of the shift register 7 while one output signal of the counter 8 is turned on. The control unit 10 controls the above-described units except the host control unit microcomputer 4.

Next, the encoding operation of the image information encoding apparatus according to the present embodiment having the above configuration will be described.

When the image information encoding apparatus starts an encoding operation, first, as shown in FIG. 3, the selectors 5 and 6 are switched to the code table 2 side (process 101) to encode one line. The operation is executed (process 102). This encoding operation is performed as shown in FIG.

That is, when the above operation is started, binary image information of each line is sequentially input one pixel at a time from an external device such as a scanner. When the image information is input, the run length detecting unit 1 reads the image information (step 20).
1), a change in black and white pixels is determined (process 202). If white or black has not changed continuously (step 20)
2), the reading is repeated (to process 201).
When a change in black and white is detected (Y in process 202),
The run length which is the continuous number of white or black is counted (process 20).
3).

Next, the control unit 10 determines the run length (step 204). If the run length is, for example, 64 or less (Y in step 204), the code selecting unit 3 selects word data for the terminating code in the code table 2 (step 205). Next, code data as word data corresponding to the run length and control data are read from the code table 2 (process 206).

The read code data is supplied to the selector 5
, And the control data is
The data is input to the counter 8 via the selector 6. Control unit 7
Turns on the load signal L to the shift register 7 and the counter 8, sets the code data in the shift register 7, and sets the control data in the counter 8. Further, a predetermined clock signal CK is supplied to the shift register 7 and the counter 8. Thus, the counting operation of the counter 8 starts.

The MH code is composed of various bit patterns having a bit length of 2 to 13 bits, as is clear from the code table of the CCITT recommendation.
For each code having a bit length exceeding 8 bits, the ninth and subsequent bits counted from the right are all bits “0”.

Each code in the code table 2 shown in FIG. 2 shows the MH code as it is when the bit length of the corresponding MH code is 8 bits or less, and when the bit length is 9 bits or more, the MH code 8 shows a bit pattern of 8 bits on the right side of FIG. The control data indicates the complement of the bit length of the MH code.

If an MH code having a bit length of 4 bits is taken as an example, the word data in the code table 2 in this case has a 4-bit code "d" as shown in FIG.
1d2d3d4 "and control data" 11
00 ”.

Assuming that the control data "1100" is set in the counter 8, the counter 8 sets the value as an initial value every time the clock signal CK is input for one pulse as shown in FIG. , The count values Q1 to Q4 are sequentially counted up.

The fourth bit Q4 of the counter 8 is initially "1".
This signal is input as a shift enable signal SE of the shift register 7. Accordingly, the shift register 7 sequentially outputs the codes d1 to d4 in synchronization with the clock signal CK. These codes d1 to d4
Is output as a coded data CD from the AND circuit 9 as a serial signal. In this way, a predetermined terminating code is generated (the above is the process 207).

On the other hand, the same processing as described above is executed for the next image information in parallel with this data output operation (processing 20).
1).

In the above case, when four pulses of the clock signal CK are input, the counter 8 overflows and turns on the carry signal C. When carry signal C is turned on, control unit 10 shifts the next code data to shift register 7.
Then, control data is set in the counter 8 and the next code generation operation is repeated in the same manner.

FIG. 5C shows word data in the case of an MH code having a bit length of 11 bits. In this case, the code data is “d1d2... D8”, and the control data is an 11's complement “0101”.

Therefore, the above-mentioned "0101" is stored in the counter 8.
Is set, and a counting operation is performed as shown in FIG.
The output Q4 of the counter 8 is "0" until three pulses of the clock signal CK are input. During this time, the operation of the shift register 7 stops, and the encoded data CD output from the AND circuit 9 becomes “0”.

The output Q4 becomes "1" after the third pulse of the clock signal CK. As a result, the code data “d1 to d8” are sequentially output from the shift register 7 as the encoded data CD. In this way, predetermined encoded data of 11 bits is generated.

On the other hand, when the run length counted by the run length detecting section 1 is 64 or more and less than 1792 (step 204).
In step 208, Y in step 208), and select word data for the standard makeup code (step 20).
9). If the run length is 1792 or more (processing 2
(N of 08), the word data for the extended makeup code is selected (process 210).

Then, the word data corresponding to the run length is read from the code table 2 and set in the shift register 7 and the counter 8 in the same manner as described above (processing 21).
1). Thereby, a predetermined makeup code is generated and output from AND circuit 9 (process 212).

In this case, a terminating code having a run length corresponding to the difference between the actual run length and the run length of the generated makeup code is generated and output in the same manner as described above (to process 205).

The above-described encoding process is executed for one line of image information (the above-described process 102 in FIG. 3). Thereafter, the selectors 5 and 6 are switched to the higher-level control unit microcomputer 4 (step 103).

The image information encoding apparatus of this embodiment has a function of unifying the encoded data of each line into byte units, that is, multiples of 8 bits, and executes the operation when specified.

The host control unit microcomputer 4 determines whether or not there is a designation to unify the encoded data in byte units (step 104). If there is such designation (Y in process 104), the number of bits of the generated encoded data for one line is counted (process 105).
The number of missing bits is calculated (process 106).

Then, the host controller microcomputer 4 outputs predetermined code data to the selector 5 and outputs predetermined control data to the selector 6. In this case, the respective data are input to the selectors 5 and 6 as parallel signals from the data bus of the higher-level control unit microcomputer 4, for example. Then, the code data is set in the shift register 7 via the selector 5, and the control data is set in the counter 8 via the selector 6.

The code data is data to be added to the encoded data. In this case, the data may be 8-bit fixed data. The control data is 4-bit data indicating the complement of the number of bits of the data to be added. Thus, by the operation described with reference to FIG. 5, data of a predetermined number of bits is output from the AND circuit 9, and data bits are added to the encoded data (process 107). If there is no designation to unify encoded data in byte units (N in process 104), the above operation is not performed.

The image information encoding apparatus according to the present embodiment has a function of arbitrarily setting whether or not to insert an EOL code between lines of encoded data, and operates according to the setting made in advance.

Here, the higher-level control unit microcomputer 4 determines the setting (step 108). And E
When the OL code is set to be inserted (Y in step 108), the higher-level control unit microcomputer 4
Similarly to the above, fixed code data and control data are output and set in the shift register 7 and the counter 8, respectively.

In this case, the code data is “00000”
01 ", and the control data is" 0100 ".
It is the data. As a result, the EOL code "0000000000001" is output from the AND circuit 9, and the EOL code is inserted into the encoded data (process 109). If the setting is such that the EOL code is not inserted (N in step 108), the above operation is not executed.

Thereafter, the selectors 5 and 6 are switched to the code table 2 and the above operation is repeated (step 101).
What). As a result, the image information is encoded line by line so that predetermined encoded data can be obtained.

As described above, in the present embodiment, the code data and the control data stored in the code table 2 in advance are read out, and the shift register 7 and the counter 8 read out the M data.
H code is generated. When inserting various data between lines of encoded data, predetermined code data and control data are input from the higher-level control unit microcomputer 4 to the shift register 7 and the counter 8 to generate data to be inserted. ing.

As described above, in the present embodiment, it is not necessary to store data for generating data to be inserted in the code table 2, so that the capacity of the code table 2 does not increase.

The EOL code to be inserted is data of a fixed pattern having a large bit length of 12 bits. In general, a microcomputer handles data in byte units, so preparing 12-bit data complicates data transfer processing and circuitry. In this embodiment, both the code data and control data are 8 bits or less. Therefore, the higher-level control unit microcomputer 4 directly outputs parallel signals from the data bus to the selectors 5 and 6,
An EOL code can be generated.

In the above-described embodiment, the EOL code and the data of the additional bit are inserted between the lines of the encoded data as necessary. However, in the case of the circuit shown in FIG. Thus, it is natural that various data in which the latter 8 bits are set to a desired code can be inserted. Thereby, for example, various tag bits can be arbitrarily inserted for each line.

In order to increase the number of bits of data to be inserted, the number of bits of the counter 8 may be increased. For example, if it is 8 bits, the data to be inserted can be up to 255
Can be a bit. If it is desired to operate the control data with 4 bits, the upper 4 bits of the counter 8 may be fixedly set to "1".

Further, in the above-described embodiment, the code data and the control data for generating the data to be inserted are output from the higher-level control unit microcomputer 4. However, as shown in FIG. May be provided, and their output data may be input to the shift registers 7 and 8 via the selectors 5 and 6 as necessary. As a result, the program load on the upper control unit microcomputer 4 is reduced.

In the above embodiment, the case where the image information is encoded by the MH code has been described.
Even in the MR system, a part of the code generation process is common to the MH system, and the encoding device can be configured with the same basic circuit configuration as in the present embodiment. It is conceivable that the present invention can be applied to such a case in almost the same manner.

[0053]

As described above, according to the present invention, information detected from image information is input to a code table to extract control data, and the extracted control data is input to code generation means, and code In the case where constant data is inserted between lines of encoded data while obtaining encoded data, specific control data is input to the code generation means every time encoded data for one line is output. Then, the code generator outputs a certain amount of data.
Arbitrary data can be inserted between encoded data lines, and the table memory does not need to store control data for generating the data to be inserted, so that the table memory does not have a large capacity.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image information encoding apparatus according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of data stored in a code table.

FIG. 3 is an operation flowchart of the image information encoding apparatus.

FIG. 4 is a detailed operation flowchart of an encoding process.

FIG. 5 is an operation explanatory diagram of an encoding process.

FIG. 6 is a block diagram showing a portion different from FIG. 1 in another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Run length detection part 2 Code table 3 Code selection part 4 Upper control part microcomputer 5,6 Selector 7 Shift register 8 Counter 9 AND circuit 10 Control part 11,12 Fixed data output circuit

Claims (4)

(57) [Claims] 1. An image information encoding apparatus for outputting encoded data based on a black and white run length of image information sequentially input line by line, wherein the input image information is detected in black and white and a run length. A code table for inputting the black and white and run length of the detected image information and outputting corresponding control data, and a code generation for inputting the control data and outputting the encoded data Means, and when it is necessary to insert certain data between lines of encoded data to be output, each time the code generating means outputs one line of encoded data, a specific control data is transmitted to the code generating means. And a code insertion control means for inputting the constant data and outputting the constant data. 2. The apparatus according to claim 1, wherein the code insertion control means includes means for inputting the specific control data from the data bus of the microcomputer system to the code generation means as a parallel signal. 2. The image information encoding device according to 1. 3. The code insertion control means includes a fixed data output means for fixedly outputting the specific control data, and a means for inputting the output control data to the code generation means as required. 2. The image information encoding apparatus according to claim 1, comprising: 4. The control data according to claim 1, wherein the control data comprises code data indicating a bit pattern of a part of each code and control data indicating a complement of the number of bits of each code. Image information encoding device.