JP2818323B2 - Binary image data extraction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binary image data extracting system for extracting a part of large-size image data, which is applied to a binary image compression / expansion processor.

[0002]

2. Description of the Related Art In a binary image compression / decompression processing apparatus that handles a large amount of binary images, binary images are often encoded and handled in order to speed up data transfer. As a typical encoding method used in this type of apparatus, MH (Modi
fied Huffman), MR (Modified READ), M
There is an MR (Modified MR) method.

Conventionally, when extracting a partial image from a binary image encoded by such an encoding method, all encoded code (code) data is decompressed and the original image is decompressed. Then, the desired part was cut out.

As another method, Japanese Patent Publication No. Sho 63-3
As shown in No. 3350, a one-dimensional line of image data is used to divide the image data into a plurality of segments, and a table for storing a start address of a code corresponding to a starting one-dimensional line of the segment is created. There is a method of decompressing from the middle of the image using.

[0005]

However, in the method of extracting an image after expanding it into the original image, a large number of images that are not directly related must be expanded, which increases the size of the original image. Accordingly, there is a problem that the decompression process takes a long time and the image memory requires a huge capacity.

In the method disclosed in JP-B-63-33350, in which a binary image is divided into segments and the first line of each segment is encoded by a one-dimensional encoding method, all lines are correlated with a plurality of lines. It was not possible to cope with the MMR method of encoding with a certain encoding method. Furthermore, when encoding using the MR method, it is not possible to cope with the case where the first line of each segment is encoded using a two-dimensional encoding method.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a binary image data extraction method capable of performing high-speed partial image extraction even from a large-sized binary image. The purpose is to do.

[0008]

According to the present invention, there is provided a system for compressing and decompressing a binary image, wherein each of a plurality of regions obtained by dividing the binary image by a predetermined number of lines is used to start the region. A code position data storage unit for storing the image data of the reference line corresponding to the line and the data indicating the code position of the start of the start line in the code data when the binary image is compressed, in association with each other Then, when cutting out a partial image in the binary image, an image is generated based on the data stored in the code position data storage means.

The present invention also provides a binary image compression / expansion for executing a compression process for generating code data based on binary image data or a decompression process for generating a binary image based on code data. Processing means, based on the data obtained by the processing by the binary image compression / decompression processing means,
For each of a plurality of regions obtained by dividing the binary image for every predetermined number of lines, the image data of the reference line corresponding to the start line of the region and the code data when the binary image is compressed Code position data storage means for storing data indicating the start code position of the start line in association with each other, and code data storage means for storing code data handled in the binary image compression / decompression processing means When cutting out a partial image in the binary image in the binary image compression / decompression processing means, based on the data stored in the code position data storage means, the code data storage means An image is generated by cutting out and expanding the stored code data.

In particular, the binary image compression / expansion processing means is set by the reference line setting means for setting image data of a reference line corresponding to the start line of the area immediately before the cut-out area, and the reference line setting means. Code position setting means for setting the leading code position of the start line corresponding to the reference line, wherein the code data stored in the code data storage means is transferred to the code position set by the code position setting means. The partial image is generated by skipping and expanding the code data after the start position by referring to the image data of the reference line set in the reference line setting means.

Further, the binary image compression / expansion processing means comprises:
A reference line setting means for setting image data of a reference line corresponding to the start line of the area immediately before the cut-out area; and a code position at the head of the start line corresponding to the reference line set by the reference line setting means. Code position setting means for setting, the code data stored in the code data storage means is read from the code position set by the code position setting means, the reference line set in the reference line setting means A partial image is generated by decompressing with reference to image data.

The binary image compression / expansion processing means includes a line number holding means for holding the number of lines in each area of the divided binary image, and a byte number for counting the number of bytes of the processed code data. Counting means, bit position holding means for indicating a head bit position of a code to start processing, reference line holding means for holding image data of a reference line corresponding to a line to be processed, and counting the number of processed lines The number of lines to be subjected to the expansion process counted by the line number counting unit reaches the number of lines held by the line number holding unit. Further, similarly to the compression processing, image data and data indicating a code position are stored in the code position data storage means.

The binary image compression / expansion processing means includes a line number holding means for holding the number of lines in each area of the divided binary image, and a byte number for counting the number of bytes of the processed code data. Counting means, bit position holding means for indicating a head bit position of a code to start processing, reference line holding means for holding image data of a reference line corresponding to a line to be processed, and counting the number of processed lines The number of lines to be subjected to the compression processing counted by the line number counting means during the compression processing reaches the number of lines held by the line number holding means. The image data held by the reference line holding means, the number of bytes counted by the byte number counting means, and the image data held by the bit position holding means. Data indicating a code position indicated by the first bit position, and stored in the code position data storage means.

[0014]

According to this structure, the image data of the reference line corresponding to the start line of the area and the data indicating the leading code position of the start line in the code data are stored in association with each other. When the image is cut out, that is, when the image data corresponding to the desired cut-out area is expanded, the image data of the reference line can be referred to, so that the MR method and the MMR method can be used.

In particular, the compression / expansion processing means skips the code data stored in the code data storage means up to the code position set by the code position setting means, and does not perform unnecessary data expansion processing. so,
The cutout processing is sped up.

Further, when the code data stored in the code data storage means can be read from an arbitrary position,
The compression / decompression processing means reads out the code data stored in the code data storage means from the code position set by the code position setting means so that unnecessary data decompression processing is not performed, and furthermore, the cutout processing is performed at high speed. Can be

Further, the code position data storage means includes a line number holding means, a byte number counting means, a bit position holding means, a reference line holding means, and a line number counting means provided in the binary image compression / decompression processing means. Based on the content,
At the time of compression processing, image data of a reference line and data indicating a code position at the head of a start line are stored.
Further, when the binary image has already been encoded, the contents of the line number holding means, byte number counting means, bit position holding means, reference line holding means, and line number counting means are used during the decompression processing. Based on this, the image data of the reference line and the data indicating the leading code position of the start line are stored.

[0018]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a binary image compression / expansion processing apparatus in a system to which a binary image data extraction system according to the embodiment is applied. As shown in FIG. 1, the binary image compression / decompression processing device 10 includes a change point detection circuit 12, a decoding circuit 14, a generation circuit 16, an I / O register group 18, a byte counter 20, a line counter 22, a pointer buffer 24, 26, and reference line image memory 2
7 and a CPU via a system bus 28.
(Not shown).

The present system stores code data given to the binary image compression / decompression processing device 10 at the time of image decompression, and information and the like as an intermediate start table 50 (code position data storage means) described later. An apparatus (not shown) is provided. It is assumed that image data to be subjected to image compression is input to the system by an image input device (not shown) such as an ITV.

The change point detection circuit 12 detects a change point from the image data of the line (reference line) immediately before the line to be decoded or encoded stored in the reference line image memory 27. is there.

The decoding circuit 14 inputs a code (code data) at the time of image expansion and inputs image data at the time of image compression to decode the data.

The generation circuit 16 generates image data at the time of image expansion and code data at the time of image compression based on the change points detected by the change point detection circuit 12 and the result decoded by the decoding circuit 14. Things.

An I / O register group 18 holds various data used for compression / expansion processing in the same device, and includes therein a line number n for dividing an image into a plurality of divided areas. (Line number holding means).

The byte counter 20 counts the number of bytes of the code data from the first byte of the code data when the image is expanded. The pointer buffer 24
In the decompression process, the decoding circuit 14 indicates the position of the first bit of the code to start decoding in the code data.

The line counter 22 counts up to the number n of lines in the divided area set in the I / O register group 18 every time the compression / expansion processing is executed for one line. The pointer buffer 26 indicates the first bit position where the codes in the code data should be joined to the generation circuit 16 during the compression processing.

Next, a data structure in the embodiment will be described. FIG. 2 shows a conceptual diagram of the image data 30 corresponding to the original image. FIG. 3 shows the image data 30 shown in FIG.
2 is a conceptual diagram of two-dimensionally arranged code data 40 corresponding to. FIG. 4 is a conceptual diagram of an intermediate start table 50 generated at the time of image compression or decompression processing and used when performing partial image clipping.

The image data 30 shown in FIG. 2 is divided into a plurality of divided areas 30-1, 30-2,... Every n lines. The code data 40 shown in FIG. 3 is shown in association with the image data 30 shown in FIG. In general, the length of encoded data differs depending on the content of the data even if image data of the same length is encoded. Therefore, on the encoded data, each divided area 40-1, 40-2,. Have no regularity at the head position (head positions 0, 1, 2,...).

The intermediate start table 50 shown in FIG. 4 stores each divided area 30- in the image data 30 shown in FIG.
, 30-2,..., And from the head in the code data 40 indicating the head position (code start position) of each of the divided areas 40-1, 40-2,. And the bit position in the byte are stored in association with each other. In the image data of the reference line corresponding to the first line (encoding line) of the first divided area 30-1, all bits are “0” indicating white.

In the intermediate start table 50, the divided areas in the image data 30 and the corresponding code data are made to correspond one-to-one. Therefore, for example, when partially extracting an image from the compressed image data, the image data 30
If the divided area including the partial image to be cut out is known in,
By referring to the code start position of the corresponding divided area in the code data 40 from the intermediate start table 50, decoding is started from that address, and if decoding of the required number of lines is completed, decoding is stopped there. Necessary data can be efficiently extracted.

Next, the operation of the embodiment will be described.

Here, the binary image compression / decompression processing device 10
1 will be described with reference to FIGS. 1 to 4. FIG.

First, the intermediate start table 5 shown in FIG.
A method of creating 0 will be described. First, the I / O register group 18 is accessed, and the number n of lines in the divided area in the image data 30 is set. The intermediate start table 50 is created at the time of image compression when the original data is image data, and is created at the time of the first image decompression when the original data is code data.

When image data or code data is input to (the decoding circuit 14 of) the binary image compression / expansion processing apparatus 10, the compression processing or expansion processing is sequentially executed. At this time, every time the processing for one line is executed, the number of processed lines is counted by the line counter 22. Also,
The number of bytes of the created code data (at the time of compression) or the number of bytes of the input code data (at the time of expansion) is counted by the byte counter 20.

When the count value of the line counter 22 reaches a value indicating that the processing for the preset number of lines (n) has been completed, the binary image compression / expansion processing device 10
Generate a U interrupt. At the time of compression, the contents of the pointer buffer 26 indicate the first bit position to which the code of the next line should be connected. Also, at the time of extension,
The contents of the pointer buffer 24 indicate the start bit position (code start position) of the code at which decoding of the next line is to be started.

Here, according to an I / O instruction from the CPU,
The reference line data and the contents of the byte counter 20 and the pointer buffer 26 (at the time of compression) or the contents of the pointer buffer 24 (at the time of expansion) are read via the system bus 28.

On the system side, the data read from the binary image compression / decompression processor 10 is stored in the intermediate start table 5.
0 is sequentially stored. Here, the reference line data is the image data of the reference line corresponding to the first line in the divided area to be processed next. The image data of the reference line is associated with the byte position from the head in the code data 40 and the bit position in the byte. The code data 40 associated with the compression / decompression processing corresponding to the contents stored in the intermediate start table 50
(See FIG. 3).

Thereafter, the processing in the binary image compression / expansion processing apparatus 10 is restarted. Then, the above processing is continuously performed on the entire image data, whereby the intermediate start table 50 for each divided area in the entire image is created.

Next, a specific operation of performing a partial decompression process (cutting out a partial image) using the intermediate start table 50 will be described.

When extracting and expanding image data,
The data is read from the code data 40 and the intermediate start table 50 and executed. Here, the expansion processing is performed from the nearest divided area closest to the desired cutout area.
Therefore, before starting the decompression processing, the image data of the reference line corresponding to the line at the beginning of the divided area and the code start position corresponding to this data are stored in the intermediate start table 5.
It is read from 0.

The read data is transmitted to the system bus 28
To the binary image compression / decompression processing device 10 via
In the binary image compression / decompression processing device 10, the I / O
By the O command, the image data of the reference line is stored in the reference line image memory 27, and the byte position indicating the code start position and the bit position in the byte are set in the byte counter 20 and the pointer buffer 24, respectively.

When the decompression process is started and the code data 40 is input to the decoding circuit 14, the byte counter 20 is counted down every time one byte is input. The input code data is skipped while the value of the byte counter 20 is "0". That is, decompression processing is not performed on unnecessary code data before the divided area including the image to be extracted. When the code data is sequentially input and the value of the byte counter 20 becomes "0", it means that the byte including the code data at the head of the area where the desired decompression should be started is taken. The pointer buffer 24 indicates the decoding start position in the byte.

If the code data 40 can be read from an arbitrary position, the data may be input from the byte position of the code data 40 indicated by the byte counter 20 when the decompression process is started. . As a result, the time for skipping unnecessary code data before the divided area can be further reduced.

Here, the change point detection circuit 12 detects the change point of the reference line corresponding to the coding line (the leading line of the divided area) based on the reference line data stored in the reference line image memory 27. Perform On the other hand, decryption circuit 1
4 performs decoding from the decoding start position indicated by the contents of the pointer buffer 24. The generation circuit 16 generates an image according to the detection result of the change point in the change point detection circuit 12 and the decoding result in the decoding circuit 14.

Hereinafter, an image is sequentially generated for the input code data. The decompression process is performed only on the divided region including the partial image to be extracted. If decoding of the required number of lines is completed in the middle of one divided area, the decompression process is terminated there.

In this way, for each of a plurality of divided areas obtained by dividing an image every n lines, the image data of the reference line corresponding to the head line and the information indicating the code start position are associated with each other. It is stored in the intermediate start table 50.

Therefore, when a partial image is cut out, expansion processing is performed only on a divided area including the partial image based on the information indicated by the code start position stored in the intermediate start table 50.

In this method, since the decompression process is not performed on a large number of images which are not directly related, the extraction of the partial image can be performed efficiently, and a huge image memory capacity is not required. Further, since the intermediate start table 50 stores the image data of the reference line in association with the information indicating the code start position, by using this data, a system that performs encoding using the MMR method is also supported. it can. In the MR system,
It is not necessary to limit the start line of the divided area to a one-dimensional line.

[0048]

As described above, according to the present invention, when compressing or decompressing an image, the image data of the reference line from which the image can be partially cut out and the information indicating the code start position with respect to the encoded image data. Is stored, the partial cutout of the image can be performed at high speed by using this information.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a binary image compression / expansion processing apparatus in a system to which a binary image data extraction system according to an embodiment of the present invention is applied.

FIG. 2 is a conceptual diagram of image data corresponding to an original image.

3 is a conceptual diagram of two-dimensionally arranged code data corresponding to the image data shown in FIG. 2;

FIG. 4 is a conceptual diagram of an intermediate start table.

[Explanation of symbols]

10: binary image compression / expansion processing device (binary image compression / expansion processing means), 12: change point detection circuit, 14: decoding circuit, 1
6 ... Generating circuit, 18 ... I / O register group, 20 ... Byte counter (byte number counting means), 22 ... Line counter (line number counting means), 24, 26 ... Pointer buffer (bit position holding means), 27 ... Reference line image memory (reference line holding means), 28 ... System bus.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 1/41-1/419 H04N 1/38-1/393

Claims (6)

(57) [Claims] 1. A system for compressing and decompressing a binary image, wherein each of a plurality of regions obtained by dividing the binary image by a predetermined number of lines includes a reference line corresponding to a start line of the region. A code position data storage unit for storing image data and data indicating the code position of the start of the start line in the code data when the binary image is compressed, in association with each other, Wherein the image is generated based on the data stored in the code position data storage means when the partial image is extracted. 2. A compression processing for generating code data based on data of a binary image, or a decompression processing for generating a binary image based on code data in a system for compressing and expanding a binary image. A binary image compression / expansion processing means for executing a plurality of lines obtained by dividing the binary image by a predetermined number of lines based on data obtained by the processing by the binary image compression / expansion processing means. For each of the regions, the image data of the reference line corresponding to the start line of the region and the data indicating the leading code position of the start line in the code data when the binary image is compressed are stored in association with each other. Code position data storage means, and code data storage means for storing code data handled in the binary image compression / decompression processing means. When the binary image compression / expansion processing unit cuts out a partial image in the binary image, the binary image is stored in the code data storage unit based on the data stored in the code position data storage unit. A binary image data extraction method, wherein an image is generated by extracting and expanding code data. 3. The binary image compression / expansion processing means includes: a reference line setting means for setting image data of a reference line corresponding to a start line of a region immediately before the cut-out area; and a reference line setting means. Code position setting means for setting a head code position of a start line corresponding to the reference line thus set, wherein the code data stored in the code data storage means is converted to a code position set by the code position setting means. 3. A partial image is generated by skipping up to the start position and expanding the code data after the start position by referring to the image data of the reference line set in the reference line setting means. Binary image data extraction method. 4. A reference line setting means for setting image data of a reference line corresponding to a start line of a region immediately before a cut-out area, wherein the reference image is set by the reference line setting means. Code position setting means for setting a head code position of a start line corresponding to the reference line thus set, wherein the code data stored in the code data storage means is converted to a code position set by the code position setting means. 3. A binary image data extracting method according to claim 2, wherein a partial image is generated by reading out from a reference line and expanding the image by referring to image data of a reference line set in the reference line setting means. 5. A binary image compression / expansion processing means, comprising: a line number holding means for holding the number of lines of each area of the divided binary image; and a byte number for counting the number of bytes of the processed code data. Counting means; bit position holding means for indicating a head bit position of a code to start processing; reference line holding means for holding image data of a reference line corresponding to a line to be processed; and counting the number of processed lines Line number counting means, and the number of lines to be subjected to expansion processing counted by the line number counting means at the time of expansion processing has reached the number of lines held by the line number holding means. At this time, the image data held in the reference line holding means, the number of bytes counted by the byte number counting means, and the number of bytes held in the bit position holding means are stored. Leading data indicating a code position indicated by the bit position, the binary image data cutting method of the second claim, wherein the storing the code position data storage means has. 6. A binary image compression / expansion processing means, comprising: a line number holding means for holding the number of lines in each area of the divided binary image; and a byte number for counting the number of bytes of the processed code data. Counting means; bit position holding means for indicating a head bit position of a code to start processing; reference line holding means for holding image data of a reference line corresponding to a line to be processed; and counting the number of processed lines Line number counting means, and the number of lines to be subjected to the compression processing counted by the line number counting means during the compression processing has reached the number of lines held by the line number holding means. At this time, the image data held in the reference line holding means, the number of bytes counted by the byte number counting means, and the number of bytes held in the bit position holding means are stored. Leading data indicating a code position indicated by the bit position, the binary image data cutting method of the second claim, wherein the storing the code position data storage means has.