JP3247754B2 - Image transmission 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 encoding / decoding means for encoding and compressing image data obtained by raster-scanning a transmission original and decoding the encoded image information into original image data. The present invention relates to an image transmission apparatus for exchanging image data in a state where the image data is encoded and compressed.

[0002]

2. Description of the Related Art For example, in an image transmission apparatus such as a facsimile apparatus, the amount of information of image data to be transmitted is very large. Therefore, if image data is directly exchanged, the transmission time becomes extremely long and the communication cost becomes excessive. The image data is transmitted after being encoded and compressed.

[0003] As a method of encoding and compressing the image data, generally, a one-dimensional run-length encoding system (typically, an MH (Modified Huffman) encoding system) and a two-dimensional run-length encoding system (standard, generally). MR
(Modified READ) coding method or MM
A run-length coding scheme such as R (Modified MR) coding scheme has been used. In recent years, an arithmetic coding scheme (eg, an arithmetic coding scheme having a higher coding compression efficiency than such a run-length coding scheme) has been used. , QM-code
r) is also being applied.

When this arithmetic coding method is applied, irrespective of the content of the image, that is, whether or not the transmitted original includes a picture (halftone image), the arithmetic coding method is more effective than when the run-length coding method is applied. Thus, the data amount of the formed code data (image information) can be reduced. For example, compared to the MMR coding method having the highest coding compression rate, the QM-coder coding method can reduce the data amount by about 20% when no halftone image is included, and when the halftone image is included. , The data amount can be reduced by about 200% at the maximum.

[0005]

However, the arithmetic coding method has a more complicated coding process than the run-length coding method.
A device that encodes and decodes image data using an arithmetic coding method has a disadvantage that the processing speed is slower than a device that encodes and decodes image data using a run-length coding method.

Accordingly, when an arithmetic coding / decoding device is applied to a group 4 facsimile apparatus using an ISDN having a high data transmission rate as a transmission line, the processing speed of the coding / decoding device becomes a bottleneck. Therefore, there is a possibility that the data transmission cannot be continuously performed, and the total communication cost increases.

[0007] The present invention has been made in view of such circumstances, and has as its object to provide an image transmission apparatus capable of performing efficient data transmission.

[0008]

SUMMARY OF THE INVENTION The present invention provides an encoding / decoding method for encoding and compressing image data obtained by raster-scanning a transmission original and decoding the encoded image information into original image data. Means for transmitting and receiving image data in a state where the image data is encoded and compressed, wherein a plurality of encoding and decoding means having different encoding compression rates and encoding processing speeds of image data and a plurality of data having different transmission speeds are provided. Transmitting means, and selecting one of the data transmitting means to be used, and selecting the plurality of codes based on an image data encoding / compression rate and an encoding processing speed in accordance with the transmission rate of the selected data transmitting means. It is provided with control means for selecting one to be used from the decryption means.

The image processing apparatus further includes an encoding / decoding means for encoding / compressing image data obtained by raster-scanning a transmission original and decoding the encoded image information into original image data. In an image transmission apparatus for exchanging in a compressed state, an image reading unit capable of reading a transmission original in a halftone mode and a non-halftone mode,
A plurality of encoding / decoding means having different encoding compression rates and encoding processing speeds of image data, a plurality of data transmission means having different transmission speeds, and selecting a reading mode of the image reading means; Of the plurality of coding / decoding means based on the coding compression rate and coding processing speed of the image data in accordance with the combination of the selected reading mode and the transmission speed of the data transmission means. And a control means for selecting one to be used.

The image processing apparatus further includes an encoding / decoding means for encoding / compressing image data obtained by raster-scanning a transmission original and decoding the encoded image information into original image data. A first encoding / decoding means for encoding / decoding image data in a predetermined run-length encoding system, and an image encoding device for encoding image data in a predetermined arithmetic encoding system A second encoding / decoding means for decoding, a plurality of data transmission means having different transmission speeds, and selecting one of the data transmission means to be used, and the selected data transmission means having a high transmission speed The first encoding / decoding unit is selected according to the encoding compression rate and encoding processing speed of image data, and the transmission speed of the selected data transmission unit is low. The case, in which a control means for selecting the second encoding and decoding means in accordance with the encoding compression rate and the coding processing speed of the image data.

The image processing apparatus further includes an encoding / decoding means for encoding and compressing image data obtained by raster-scanning the transmission original and decoding the encoded image information into original image data. In an image transmission apparatus for exchanging in a compressed state, an image reading unit capable of reading a transmission original in a halftone mode and a non-halftone mode,
First encoding / decoding means for encoding / decoding image data by a predetermined run-length encoding method, and second encoding / decoding means for encoding / decoding image data by a predetermined arithmetic encoding method. A plurality of data transmission means having different transmission speeds,
While selecting the reading mode of the image reading means, while selecting one of the data transmission means to be used, when selecting a non-halftone mode as the reading mode and selecting the data transmission means having a large transmission speed, The first encoding / decoding means is selected according to the encoding compression rate and the encoding processing speed of the image data, and when the combination of the selected reading mode and the transmission speed of the data transmission means is other than that, It is provided with control means for selecting the second coding / decoding means according to the coding compression rate and coding processing speed.

[0012]

Therefore, the most efficient encoding mode is selected according to the data transmission speed and the characteristics of the image, so that the data transmission efficiency can be improved and the communication cost can be reduced.

[0013]

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

FIG. 1 shows a facsimile apparatus according to one embodiment of the present invention. This facsimile machine has I
It uses SDN as a transmission path, and has a group 4 facsimile function and a group 3 facsimile function.

In FIG. 1, a control unit 1 executes operation control processing of the facsimile apparatus, group 3 facsimile transmission procedure processing, group 4 facsimile transmission procedure processing of an upper layer, and the like. The storage unit stores a processing program to be executed by the control unit 1 and various data necessary for executing the processing program, and configures a work area of the control unit 1.

The parameter memory 3 stores various information unique to the facsimile machine.
It is composed of a rewritable nonvolatile semiconductor storage device such as a battery-backed SRAM (static random access memory).

The scanner 4 is for reading a document image at a resolution set in the group 4 facsimile apparatus, and has a halftone mode and a non-halftone mode as image reading modes. Also, the plotter 5
The image is recorded and output at the resolution set in the group 4 facsimile apparatus.

The operation display unit 6 is used to operate the facsimile machine, and includes various operation keys and
It comprises various display devices such as a liquid crystal display for displaying guidance information and the like to the operator.

The image processing section 7 is for converting the pixel densities of the images of the scanner 5 and the plotter 6 to each other when the pixel densities of the images that can be transmitted by the destination terminal device are different from each other. It is.

The arithmetic coding / decoding section 8 converts the image signal into a QM-
In addition to encoding and compression using the coder method, QM-co
This is for decoding the image information that has been encoded and compressed by the der method into the original image signal. The run-length encoding and decoding unit 9 encodes and compresses the image signal by the MMR method. This is for decoding the image information that has been encoded and compressed by the system into the original image signal.

The image storage device 10 stores various information such as transmission image information and reception image information.

The ISDN interface circuit 11 includes an ISDN
Physically connected to DN and ISDN Layer 1
Signal processing function and integration of D channel (signal channel) signal and two B channel (information channel) signals /
It has a separating function.

The D channel transmission control unit 12 is for performing transmission control processing such as call control processing performed with ISDN using the D channel.
Numeral 3 is for performing transmission control processing of layers 2, 3, 4, and 5 in group 4 facsimile transmission control processing using the ISDN B channel.
Is for performing signal conversion processing of analog signal / digital data for transmitting an analog signal using the ISDN B channel.

The group 3 facsimile modem 15 is for realizing a group 3 facsimile modem function. The group 3 facsimile modem 15 is a low-speed modem function (V.21 modem) for exchanging transmission procedure signals and mainly transmits image information. It has a high-speed modem function for exchange (V.29 modem, V.27ter modem, etc.).

Control unit 1, system memory 2, parameter memory 3, scanner 4, plotter 5, operation display unit 6, image processing unit 7, arithmetic coding and decoding unit 8, run-length coding and decoding unit 9, image storage Device 10, D-channel transmission control unit 12, B-channel transmission control unit 13, CODEC 14,
The group 3 facsimile modem 15 is connected to an internal bus 16, and various types of information are exchanged between these components mainly via the internal bus 16.

As described above, the facsimile apparatus according to the present embodiment is provided with two types of encoding / decoding means of the arithmetic encoding / decoding unit 8 and the run-length encoding / decoding unit 9. The encoding / decoding means is selected in accordance with the type of the transmission path used at that time and the type of the reading mode of the scanner 4.

For example, when the image signal is encoded and compressed using the arithmetic encoding and decoding unit 8, the read image (1
The relationship between the content of (for a page) and the formed code amount (code data amount) is as shown by a curve CV1 in FIG. When the image signal is encoded and compressed using the run-length encoding unit 9, the relationship between the content of the read image and the amount of code to be formed changes as shown by a curve CV2 in FIG.

That is, the amount of code is smaller when the arithmetic coding / decoding unit 8 is used in both cases where the original image has many character images and where there are many pictures (halftone images). At the same time, when the original image is composed of only character images and is read in the non-halftone mode, the absolute amount of code amount is small. When the original image is composed of only pictures and is read in the non-halftone mode, the absolute amount of code amount is small. The amount increases.

On the other hand, when encoding / decoding the same original image, the arithmetic encoding / decoding unit 8 has complicated processing contents.
Requires a longer time for the processing than the run-length encoding / decoding unit 9.

On the other hand, when the group 3 facsimile function is used, the transmission speed of image information is 9.6 (Kbps).
(In the case of a V.29 modem), whereas group 4
When the facsimile function is used, the transmission speed of image information is a very large value of 64 (Kbps).

From the above, at the time of immediate image transmission in which a document image is transmitted while being read, the encoding / decoding means to be used is selected under the following conditions.

(1) When the group 3 facsimile function is used, since the transmission speed is slow, the data transmission portion has the greatest influence on the transmission time during image transmission. Therefore, when the group 3 facsimile function is used, the amount of codes to be transmitted is reduced by using the arithmetic coding and decoding unit 8.

(2) When the group 4 facsimile function is used, since the transmission speed is high, the portion for creating the transmission data (that is, the encoding / decoding means) has the most influence on the transmission time during image transmission. Therefore, when the group 4 facsimile function is used, the time required for creating transmission data can be reduced by using the run-length encoding / decoding section 9.

(3) When the image is read in the halftone mode, the absolute value of the code amount is large. However, when the arithmetic coding / decoding unit 8 is used, the arithmetic coding / decoding unit 8 is used more than when the run-length coding / decoding unit 9 is used. Since the code amount can be reduced, the arithmetic coding and decoding unit 8 is used in this case.

Therefore, in this embodiment, by selecting the encoding / decoding means to be used under such conditions, the transmission time required for image transmission can be reduced, and the communication cost can be reduced. Can be.

FIG. 3 and FIG. 4 show an example of processing at the time of image transmission of the apparatus of FIG.

First, the user inputs destination information operated and input (process 101), and sets transmission conditions (eg, image reading mode (halftone / non-halftone), group 3 facsimile mode or Group 4
(Setting of facsimile mode, etc.) (process 10)
2).

Here, it is checked whether the halftone mode is set as the image reading mode (decision 10).
3) When the result of the judgment 103 is YES, a QM mode indicating that the arithmetic coding / decoding section 8 is used is set as a coding mode (process 106).

When the result of the judgment 103 is NO, it is checked whether or not the group 4 facsimile mode is set at that time (decision 105).
When the result of No. 5 is NO, the process proceeds to step 104. When the result of the determination 105 is YES, the MMR mode indicating that the run-length encoding / decoding unit 9 is used is set as the encoding mode (processing 10).
6).

When the setting of the encoding mode is completed in this way, it is checked whether the group 4 facsimile mode is set at that time (decision 107). If the result of determination 107 is YES, group 4 facsimile mode is set as the device mode (process 10).
8) Call the designated destination in group 4 facsimile mode (process 109).

Next, a predetermined call setting procedure is executed (processing 110), a B channel to be used at that time is established (processing 111), and transmission of a predetermined group 4 facsimile mode is performed on the established B channel. By executing the pre-procedure, the transmission function to be used at that time, such as the encoding mode, is specified to the partner terminal (process 112).

Then, the scanner 4 is operated in the reading mode designated at that time to read the transmission original image, and the image signal obtained thereby is subjected to arithmetic coding corresponding to the coding mode set at that time. The image signal is transferred to the decoding unit 8 or the run-length encoding / decoding unit 9 to encode and compress the image signal, and the image information obtained thereby is transmitted to the partner terminal (processing 113, 114, 115).

When the image transmission is completed, a predetermined post-transmission procedure is executed (step 116), the B channel is ended (step 117), and a predetermined call setting release procedure is executed (step 11).
8) End a series of transmission operations.

When the group 3 facsimile mode is set and the result of the determination 107 is NO, the group 3 facsimile mode is set as the apparatus mode (process 120), and the apparatus is designated in the group 3 facsimile mode. The called destination is called (process 121).

Next, a predetermined call setting procedure is executed (processing 122), a B channel to be used at that time is established (processing 123), and transmission of a predetermined group 3 facsimile mode is performed on the established B channel. By executing the pre-procedure, the transmission function to be used at that time, such as the modem speed and the encoding mode, is specified to the partner terminal (process 124).

Then, the scanner 4 is operated in the reading mode designated at that time to read the transmission original image, and the image signal obtained thereby is converted by the image processing section 7 into the resolution of the group 3 facsimile mode. The image signal whose resolution has been converted is transferred to the arithmetic encoding / decoding unit 8 or the run-length encoding / decoding unit 9 corresponding to the encoding mode set at that time, and the image signal is encoded and compressed. Then, the obtained image information is transmitted to the partner terminal (processing 125, 126, 127, 128).

When the image transmission is completed, a predetermined B channel termination procedure is executed (process 129), and then the process 118 is performed.
Then, a predetermined call setting release procedure is executed, and a series of transmission operations is completed.

As described above, according to the present embodiment,
Depending on the combination of the data transmission speed on the line to be used and the reading mode of the original image, either the QM-coder method or the MMR encoding method is selected, and the image signal read by the scanner 4 is encoded. Because of the compression, the transmission time can be efficiently reduced, and the communication cost can be reduced.

As the conditions for selecting the encoding method in the above-described embodiment, when the image reading mode (for example, color reading) or the resolution is different, other conditions can be used. Further, in the above-described embodiment, the case where the present invention is applied to a facsimile apparatus has been described. However, the present invention can be similarly applied to other image transmission apparatuses.

[0050]

As described above, according to the present invention,
The most efficient encoding mode is selected according to the data transmission speed and the characteristics of the image, so that the data transmission efficiency can be improved and the communication cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a facsimile apparatus according to one embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the type of image and the code amount in the QM-coder method and the MMR method.

FIG. 3 is a flowchart showing a part of a processing example executed by the apparatus of FIG. 1 at the time of transmission.

FIG. 4 is a flowchart showing another part of the processing example executed by the device of FIG. 1 at the time of transmission.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control unit 2 system memory 8 arithmetic coding and decoding unit 9 run-length coding and decoding unit

Claims (4)

(57) [Claims] An encoding / decoding means for encoding / compressing image data obtained by raster-scanning a transmission original and decoding encoded image information into original image data is provided. A plurality of encoding / decoding units having different encoding / compression rates and encoding processing speeds of image data, a plurality of data transmission units having different transmission speeds, and the data transmission unit. Select the one to use, and according to the transmission speed of the selected data transmission means,
An image transmission apparatus, comprising: a control unit that selects one of the plurality of encoding / decoding units to be used based on an encoding compression rate and an encoding processing speed of image data. 2. An encoding / decoding means for encoding / compressing image data obtained by raster-scanning a transmission original and decoding encoded image information into original image data. An image transmission device for exchanging images in a halftone mode and a non-halftone mode in an image transmission apparatus that exchanges images in a compressed state, and a plurality of encoding units having different encoding compression rates and encoding processing speeds of image data. Decoding means, a plurality of data transmission means having different transmission speeds, and selecting a reading mode of the image reading means, selecting one of the data transmission means to be used,
A control for selecting one of the plurality of encoding / decoding means to be used based on the selected compression mode and the transmission speed of the data transmission means, based on the encoding / compression ratio of the image data and the encoding processing speed. An image transmission apparatus comprising: 3. An encoding / decoding means for encoding / compressing image data obtained by raster-scanning a transmission original and decoding encoded image information into original image data. A first encoding / decoding means for encoding / decoding image data in a predetermined run-length encoding system, and encoding image data in a predetermined arithmetic encoding system. A second encoding / decoding means for decoding; a plurality of data transmission means having different transmission speeds; selecting one of the data transmission means to be used; and a case where the transmission speed of the selected data transmission means is high. The method includes selecting the first encoding / decoding unit according to the encoding compression rate and encoding processing speed of image data, and selecting the first encoding / decoding unit when the transmission speed of the selected data transmission unit is low. The image transmission apparatus characterized by comprising a control means for selecting the second encoding and decoding means in accordance with the encoding compression rate and the coding processing speed of the image data. 4. An encoding / decoding means for encoding / compressing image data obtained by raster-scanning a transmission original and decoding encoded image information into original image data, and encoding the image data. An image transmission device for exchanging image data in a halftone mode and a non-halftone mode in an image transmission apparatus for exchanging in a compressed and compressed state, and a first method for encoding and decoding image data by a predetermined run-length encoding method Encoding / decoding means, second encoding / decoding means for encoding / decoding image data by a predetermined arithmetic encoding method, a plurality of data transmission means having different transmission speeds, reading of the image reading means Mode and the data transmission means to be used is selected, while the non-halftone mode is selected as the reading mode and the data transmission speed is high. When the data transmission unit is selected, the first encoding / decoding unit is selected according to the encoding compression rate and the encoding processing speed of the image data, and the combination of the selected reading mode and the transmission speed of the data transmission unit is determined. In other cases, the image transmission apparatus further comprises control means for selecting the second coding / decoding means according to the coding compression rate and coding processing speed of the image data.