JPH04223671A - Compressing method for picture information - Google Patents

Abstract

PURPOSE:To reduce communication time and a usage charge at transmitting by a communication channel and to reduce writing time and a file capacity also at storing in an external storage device by compressing binary color picture information efficiently. CONSTITUTION:When the picture information of binary color picture information which consists of three RGB planes 31 is compressed by encoding with using run length, addresses on the respective planes are updated and a feature to provide a stage to read contents, a stage to execute the EOR operation of every bit of the contents of the plane to be basic and the contents of the plane to be compared and a stage to hold the result of the EOR operation is defined.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a color image encoding method for efficiently compressing binary color information, and in particular, to a method of encoding a color image by reading a monochrome original using an image information input device such as a scanner or fax. The present invention relates to a technique that is effective when applied to a technique for transmitting color image information obtained by drawing, deleting, etc. in color on a document using a tablet and recording it in an external storage device or transmitting it through a communication line.

0002

2. Description of the Related Art Binary image information has a large amount of information, for example, when an A4 size document is read at 200 dpi with a scanner, the amount of information is about 500 KB, so the MH method is usually used. (CCITT Recommendation T.4), MR
method (CCITT Recommendation T.4), MMR method (CCITT Recommendation T.4),
T RecommendationT. 6) Information is compressed using the encoding method using the run length (for example, "MH for facsimile").
, MR, MMR encoding system, Nikkei Data Pro Microprocessor, pages MC5-500-001-003).

[0003] When binary color image information is compressed for each plane of red, green, and blue (hereinafter referred to as RGB), it has three times the amount of information compared to binary monochrome image information. When image information is transmitted through a communication line, the communication time and line usage fees are large, and when image information is recorded on an external storage device, the writing time and file capacity are large. Therefore, it is necessary to efficiently compress binary color image information.

[0004] Therefore, when a monochrome original is read using an image information input device such as a scanner or fax, and processing such as drawing or deletion is performed on the original in color using a tablet, the original is composed of three planes of RGB. In the monochrome portion of a binary color image, the contents between the planes match. For this reason, first, after compressing and encoding one basic plane (hereinafter referred to as the basic plane) as it is,
A method has been proposed in which each plane is divided into blocks, the difference between the plane and the corresponding block of the basic plane is calculated, and only the block with the difference is encoded.

FIG. 3 shows an example of a conventional compression method for binary color image information, in which the R (red) plane is used as the basic plane and the number of divided blocks in each plane is 8. In Figure 3, as an example, the content difference is taken for the third block (R3, G3, B3) of the R, G (green), and B (blue) planes, and since G3 has a difference from R3, compression encoding is performed. However, B3 shows a case where compression encoding is not performed because there is no difference from R3.

In this case, it is necessary to add a block identification number, the start address of the block, and the size of the encoded code before the encoded code.

[0007]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when the number of blocks to be divided is small, there are few blocks whose contents match in image information where differences between planes are scattered, and the amount of information is reduced. I can't expect that.

On the other hand, when there are many blocks to be divided, there is an overhead such as block identification information, block start address, and code size after encoding binary image information in the block, so it is difficult to reduce the amount of information. I can't wait. For this reason, the number of divided blocks depends on the content of the information to be handled, and there is a problem that the number of blocks cannot be optimized and binary color image information cannot be efficiently compressed.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to efficiently compress binary color image information and reduce the communication time and line when transmitting it via a communication line. The objective is to provide technology that can reduce usage fees.

Another object of the present invention is to provide a technique that can reduce writing time and file capacity even when storing data in an external storage device.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

0012

[Means for Solving the Problems] In order to achieve the above object, the present invention reads a monochrome original by an image information input means, and converts the read image information into RGB (red, green,
This is a method of compressing image information by storing it in three plain memories (blue), drawing in color on the document using a tablet, performing processing such as deletion, and encoding it into run length. Before encoding, RGB 3
A step of determining a basic plane for binary color image information composed of two planes, and reading out contents corresponding to each of the planes to be compared with the basic plane,
Exclusive OR operation (hereinafter referred to as EOR) between this and the basic plane
The present invention is characterized by comprising a step of performing a calculation (referred to as a calculation), a step of holding the EOR calculation result, and a step of run-length encoding information on the EOR calculation result.

[0013] In other words, when compressing binary color image information consisting of three planes of RGB by encoding using run length, the addresses on each plane are updated and the contents are read out. The main feature is that the method includes a step of performing a bit-by-bit EOR operation between the contents of the basic plane and the contents of the plane to be compared, and a step of holding the result of the EOR operation.

[0014]

[Operation] According to the above-mentioned means, prior to compression encoding using run length, the basic 1 A plane (for example, R plane) is determined, the contents corresponding to each of the planes (G and B planes) to be compared with this basic plane are read out, an EOR operation is performed for each bit of both planes, and the result is held. As a result, if the two bits match, "0" is returned, and if they do not match, "0" is returned.
1" is retained. In other words, when the contents of both planes match, the EOR operation result will be "0" for all the contents of the plane. Next, the basic plane and EOR
For the remaining two planes that hold the results of calculations, an encoding method using the run length of the MH method (CCITT Recommendation T.4), MR method (CCITT Recommendation T.4), and MMR method (CCITT Recommendation T.6) The information is compressed by

[0015] In this way, binary color image information can be efficiently compressed by taking advantage of the fact that the amount of information can be reduced by performing EOR logical operations for each bit of information between planes and encoding using run length. , it is possible to reduce communication time and line usage charges when transmitting via a communication line. Also,
It is also possible to reduce writing time and file capacity when storing in an external storage device.

[0016] In order to decode the encoded information into the original binary color image information, first, the encoded information for three planes is decoded using the same method used to encode it, and the basic plane and the remaining EO for each bit for the contents of 2 planes
All you have to do is perform R calculation.

[0017]

[Embodiment] An embodiment of the image information compression method of the present invention will be explained in detail below.

FIG. 1 is a block diagram showing a schematic configuration of an example of an apparatus for implementing the image information compression method of the present invention.

In FIG. 1, reference numeral 1 denotes a document transmitted through a communication line 6, and 2 denotes an image information input device such as a scanner or a fax machine that scans the image of the document 1 and reads it in monochrome. 3 is an electronic computer such as a personal computer, and its functional configuration includes an RGB (red, green, blue) plane memory 31 that holds read binary monochrome information, an EOR calculation section 32, a result storage section 33, and an encoding control section. It is composed of a section 34 and a line control section 35. The memory 31 includes an R plane (storage area) for storing red information and a G plane (storage area) for storing green information.
It is divided into three planes: a plane (storage area) and a B plane (storage area) for storing blue information.

4 is a color display, and the display colors of the color display 4 are displayed as shown in Table 1, for example.

[0021]

[Table 1]

In other words, when the information does not have color, the information is displayed in black on a white background.

Reference numeral 5 denotes a tablet for performing processing such as color drawing and deletion on the original on the RGB (red, green, blue) plane memory 31, and its address corresponds to the color display 4. 51 is a red (R) display pen, and when this red (R) display pen 51 is pressed on the tablet 5 to draw a line, that part is displayed in red at the corresponding position on the color display 4. It is now possible to do so. 6 is a communication line.

Next, the operation of the present embodiment apparatus will be briefly explained.

As shown in FIG. 1, an image of a document 1 is read as binary monochrome image information by an image information input device 2 such as a scanner or a FAX. At that time, the binary monochrome image information is inverted and output.

The read binary monochrome image information is stored in the RGB (red, green, blue) plane memory 31 (
retained). And three RGB planes 31R,
When compressing binary color image information composed of 31G and 31B by encoding using run length, the addresses on each plane are updated, the contents are read, and the basic R plane 31R is compressed. G to compare with the contents
Contents of plane 31G and contents of R plane 31R and B
EO bitwise EOR operation with the contents of plane 31B
This is performed by the R calculation unit 32. The result of the EOR operation is held in the result holding unit 33. The result of the EOR operation held in the result holding unit 33 is read out, and the encoding control unit 34 compresses the image information by encoding it using run length, and sends it to the communication line 6 through the line control unit 35. Note that the R plane is directly sent to the encoding control unit 34 through the EOR logic operation unit 32 and result holding unit 33.

Next, the processing procedure of the image information compression method of this embodiment by the above-mentioned embodiment apparatus will be explained.

FIG. 2 is a flowchart showing the processing procedure of the image information compression method of this embodiment.

In the image information compression method of this embodiment, as shown in FIG.
Step 1 for the planes (EG, EB planes) that hold the EOR calculation results of B), R plane 31R and G plane 31G, and R plane 31R and B plane 31B.
01: Set the start address (AR, AG, AB, AEG, AEB) of each plane (R, G, B, EG, EB).

Step 102: Set the contents (DR, DG, DB) indicated by the designated addresses (AR, AG, AB) in each of the R, G, and B planes.

Step 103: Contents of step 2 above (
DR, DG, DB), a bit-by-bit EOR logical operation (EG=DG^DR, EB=DB^DR) is performed.

Step 104: The result of step 3 above (
EG, EB) are stored in the specified addresses (AEG, AEB) of the EG plane and EB plane.

Step 105: Each plane (R, G, B
, EG, EB plane).

Step 106: Repeat steps 2 to 5 for the count value of data to be compressed and encoded (until the address (AR) of the R plane reaches the maximum address).

Step 107: The data to be compressed and encoded is compressed on the R plane, which is a basic plane, on the EG plane instead of the G plane, and on the EB plane instead of the B plane.

As can be seen from the above description, according to this embodiment, three RGB planes 31R, 31G, 31B
When compressing binary color image information consisting of by encoding using run length, the addresses on each plane are updated, the contents are read, and the contents are compared with the contents of the basic R plane 31R. B plane 3 comparing the contents of G plane 31G and R plane 31R
Performs a bitwise EOR operation with the contents of 1B, and EOR
By retaining the result of the operation and performing an EOR logical operation for each bit of the content between planes before compression encoding, the amount of information after compression can be reduced, so binary color image information can be efficiently compressed. , it is possible to reduce communication time and line usage charges when transmitting via a communication line. Furthermore, it is possible to reduce writing time and file capacity when storing in an external storage device.

[0037] The present invention has been specifically explained above based on examples, but it goes without saying that the present invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof. Nor.

[0038]

As described above, according to the present invention, the amount of information after compression can be reduced by performing an EOR operation for each bit of the content between planes prior to compression encoding. It is possible to efficiently compress color image information and reduce communication time and line usage fees when transmitting it via a communication line. Furthermore, it is possible to reduce writing time and file capacity when storing in a storage device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of an example of a device that implements the image information compression method of the present invention.

FIG. 2 is a flowchart showing the processing procedure of the image information compression method of this embodiment.

FIG. 3 is a diagram for explaining problems in the prior art.

[Explanation of symbols]

1... Manuscript, 2... Image information input device, 3... Electronic computer, 3
1...RGB (red, green, blue) plane memory, 32...EO
R calculation unit, 33... Result holding unit, 34... Encoding control unit, 3
5... Line control unit, 4... Color display, 5... Tablet, 51... Red (R) display pen, 6... Communication line.

Claims (1)

[Claims] [Claim 1] A monochrome original is read by an image information input means, and the read image information is divided into three colors: red, green, and blue.
This is a method of compressing image information by storing images in a plain memory, drawing in color on a tablet, performing processing such as deletion, and encoding the image into run-length. For binary color image information consisting of three planes of red, green, and blue, there is a step of determining a basic plane, and reading out the contents corresponding to each of the planes to be compared with the basic plane. and a base plane, a step of holding the result of the exclusive OR operation, and a step of performing run-length encoding of information on the result of the exclusive OR operation. How to compress image information.