JP3298596B2 - Color image transmission apparatus and 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 color image transmission apparatus and method.

[0002]

2. Description of the Related Art A color facsimile apparatus is a typical example of a color image transmission apparatus. In a conventional color facsimile apparatus, a color space and a sub-sampling ratio can be selected and can be determined as unique parameters. That is, prior to the transmission of the image information, these parameters are negotiated with the partner terminal, and an appropriate one is selected and determined.

[0003] In the conventional color facsimile apparatus, the transmitting terminal determines the color space within the capability range of the receiving terminal.

[0004]

In the prior art, the color space and the subsampling ratio are determined independently. To make effective use of this, for example, the color space (CIE LAB, YCrCb, RGB, etc.) and the sub-sampling ratio to be used are negotiated and determined individually, which requires a complicated preprocessing, which substantially extends the communication time.

[0005] Depending on the color space, there are sub-sampling ratios that are undesirable to use. For example, in the RGB color space, each color component represents a primary color, and unless a sub-sampling ratio of 1: 1: 1 is selected, color reproducibility is impaired. That is, there is one or more subsampling ratios that can be tolerated for each color space, and it is necessary to select an appropriate combination.

In recent years, various encoding methods have been used in color facsimile apparatuses, for example, the JPEG method (CCITT recommendation T.81) and the JBIG method (CCITT recommendation T.82).
Has been proposed and the coding method and interleave format (for example, units of blocks, planes, pixels, etc.) have been proposed.
Can now be selected from multiple options.

That is, image coding attributes (or parameters) include a coding method, an interleave format, a color space, and a subsampling ratio. As preprocessing of image information transmission, a combination of a color space and a subsampling ratio is used. It is necessary to determine these appropriately.

[0008] It is an object of the present invention to provide a color image transmission apparatus and method for appropriately determining encoding attributes.

Further, when the transmitting terminal determines the color space within the capability range of the receiving terminal, for example, the output device (printer, CRT, still
Video recording devices)
There may be less favorable color spaces. For example, a CMYK color space is preferable only for printer output, but a C
The YCrCb color space is more preferable than the MYK color space. This is because extra processing for converting the color space is required, and the image quality deteriorates.

[0010] Accordingly, it is another object of the present invention to provide a color image transmission apparatus and method free of such disadvantages.

[0011]

According to the present invention, there is provided a color image transmitting apparatus capable of selecting an encoding attribute at the time of image encoding.
Storage means for storing a plurality of types of combinations, prior to image transmission, a confirmation means for confirming the reception capability of the receiving terminal about the coding attributes, receiving capability and the storage means of the receiving terminal has been identified in the check means collating the set seen if <br/> Align stored in the attribute determining means for determining a coding attributes that apply during transmission, the encoding attributes determined by said attribute determining means, transmit to Encoding means for encoding an image to be processed , wherein the confirmation means has a receiving capability of a receiving terminal.
Send a command including an instruction to determine the priority of the
Priority information included in the response corresponding to the command
And the encoding attribute determination means obtains the acquired priority order.
Position information and a plurality of combinations stored in the storage means
And a coding attribute to be used is determined .

[0012] The color image transmission apparatus according to the present invention provides a color image transmission apparatus .
Color space and subsamples for encoding corresponding to the color space
Prior to image transmission, a table storing the ring ratio and
Finding the priority of the receiving capability of the receiving terminal with respect to the color space
First transmitting means for transmitting a command including an instruction to
The command transmitted from the receiving terminal in response to the command
The spawn contains priority information about the color space
Determination means for determining whether or not the color sky
If it is determined that there is priority information on the
Priority information on space and data of the table
A color space determining means for collating and determining a color space to be used;
The color space determined by the color space determining means and the table
To determine the sub-sampling ratio.
Subsampling ratio determining means, and the color space determining means
And determined by the sub-sampling ratio determining means.
The image to be transmitted is encoded using the color space and subsampling ratio.
Encoding means for encoding, and encoding by the encoding means.
And a second transmitting means for transmitting the obtained image.
Features.

[0013] In the color image transmission method according to the present invention, transmission is performed.
Combination of multiple encoding attributes when encoding the image to be
From the sending terminal, which can be selected differently, to the receiving terminal
An image transmission method for transmitting a color image, comprising:
Prior to the
Confirmation process to be confirmed and receivers confirmed in the confirmation process
When comparing the receiving capability of the terminal with the above combination,
An attribute determining step of determining an encoding attribute to be applied to
The image to be transmitted with the encoding attribute determined in the attribute determination process
An encoding step of encoding an image, and
Includes an instruction to determine the priority of the receiving capability of the receiving terminal.
Send a response command corresponding to the command
And obtains the priority information contained in the
In the fixed process, the acquired priority information and the combination
And determine the encoding attribute to be used.
Do

[0014] The color image transmission method according to the present invention, the image
Color space and subsamples for encoding corresponding to the color space
From the transmitting terminal having a table storing the ring ratio
An image transmission method for transmitting a color image to a receiving terminal.
Prior to image transmission, the receiving terminal
Send a command that includes an instruction for priority
A first transmitting step, and the receiving corresponding to the command.
Priority for color space in response sent from the terminal
A determination process for determining whether or not ranking information is included;
In the judgment process, it is judged that there is priority information on the color space.
Priority information on the color space and the data
Color that matches the color data and determines the color space to use
A space determination step and a color sky determined in the color space determination step
Between the data in the table and the
A sub-sampling ratio determining step for determining the
Determined in the space determination process and the sub-sampling ratio determination process
Should be transmitted in the specified color space and sub-sampling ratio
An encoding step of encoding an image, and encoding in the encoding step.
A second transmission step of transmitting the digitized image.
And features.

[0015]

[0016]

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

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes C for controlling the whole.
It is a PU and includes a ROM 10a and a RAM 10b. For example, it comprises a microcomputer. Reference numeral 12 denotes an image encoding / decoding circuit which encodes an image to be transmitted and decodes a received encoded image signal. The image encoding / decoding circuit 12 can correspond to one or more conditions with respect to encoding attributes such as an encoding method, a subsampling ratio, an interleaving format, a color space, and the number of bits of a color component. At the time of image conversion, the image information is encoded with the encoding attribute specified by the CPU 10. Choices of each encoding attribute will be described later in detail.

Reference numeral 14 denotes image conversion for converting a CMYK image into an RGB image and the inverse conversion (γ conversion), a conversion from a color image to a black and white image, and a conversion from a multivalued image to a binary image. Circuit. Reference numeral 15 denotes a pixel density conversion circuit that converts the resolution and size of an image.

Reference numeral 16 denotes a frame memory used for encoding and decoding processing by the image encoding / decoding circuit 12, conversion processing by the pixel density conversion circuit 15, and image conversion processing by the image conversion circuit 14. DMA (Direct Memory Access) control circuit, 20 is a character generator (CG) for generating a character pattern signal, 22 is
A communication control circuit that controls connection with a communication line, for example, an ISDN.

Reference numeral 24 denotes a key input device for the user to input various instructions; 26, a display device for displaying various information such as out of paper, out of ink, and communication status; and 28, an image for reading a document image. The scanner 30 is a printer that prints out a received image, a report of communication status, and the like, and these are directly controlled by the I / O control circuit 32.

Reference numeral 34 denotes a well-known SCSI (or SCSI-
2) Interface, 36 is a hard disk.

Reference numeral 38 denotes an image data bus dedicated to image data, 40 denotes a system bus for system control, and the image data bus 38 includes circuits 12, 14, 15, 16, and
18, 20, 22, 28, 30, 34 are interconnected,
The system bus 40 includes circuits 10 to 22, 32,
34 are interconnected.

FIG. 2 shows an example of a combination of selectable color spaces and subsampling ratios, and FIG. 3 shows another example. The table information having contents as shown in FIG. 2 or FIG.
0 is stored in the ROM 10a. Needless to say, the color space and / or the sub-sampling ratio can be determined by unique values representing these individually, and the unique value is R
Stored in the OM 10a.

In the example shown in FIG. 2, RG is used as a color space.
B, YCrCb, and CIE LAB can be selected. The subsampling ratio is 1: 1: for the RGB color space.
1 can be selected and 1: 1: 1 for YCrCb color space.
Either 2: 1: 1 or 4: 1: 1 can be selected, and CIE
Only 1: 1: 1 can be selected for the LAB color space.

In the example shown in FIG. 3, RG is used as a color space.
B, YCrCb, CIE LAB and CMYK can be selected. As for the subsampling ratio, only 1: 1: 1 can be selected for the RGB color space, and 1: 1 for the YCrCb color space.
Either 1: 1 or 2: 1: 1 can be selected, and CIE L
Either 1: 1: 1 or 2: 1: 1 can be selected for the AB color space, and only 1: 1: 1: 1 can be selected for the CMYK color space.

The color space and the subsampling ratio are described in, for example, CCITT Recommendation T. It can be negotiated and determined by the Document Function List Command (CDCL) at 62 and the Document Function List Acknowledgment (RDCLP).

FIG. 4 shows the format of the document function list command CDCL in this embodiment. As shown in FIG. 4, a plurality of parameters follow the CDCL command, and in the non-standard function (NSC), sub-sample ratio information is inserted in addition to a country code, a country code and a supplier code.

FIG. 5 shows the format of the document function list acknowledgment RDCLP in this embodiment. As shown in FIG. 5, a plurality of parameters follow the RDCLP response, and sub-sample ratio information is inserted into the non-standard function (NSC) in addition to a country code, a country code, a supplier code, and the like. .

The color space and the sub-sampling ratio that can be permitted (or selected) between the terminals are determined by the negotiation using the CDCL command and the RDCLP response. FIG.
Indicates the color space and the sub-sampling ratio that are acceptable between the terminals when the calling terminal has the table shown in FIG. 2 and the called terminal has the table shown in FIG. Are stored in the RAM 10b of the CPU 10.

In the example shown in FIG. 6, RG is used as a color space.
Any one of B, YCrCb and CIE LAB can be selected, and as the subsampling ratio, only 1: 1: 1 can be selected for the RGB color space, and 1: 1 for the YCrCb color space.
Either 1: 1 or 2: 1: 1 can be selected, and CIE L
Only 1: 1: 1 can be selected for the AB color space.

FIG. 7 shows a flowchart of image communication according to this embodiment. Here, the ROM 10a of the calling terminal is used.
It is assumed that the table information shown in FIG. 2 is stored in the ROM 10a, and the table information shown in FIG. 3 is stored in the ROM 10a of the called terminal.

In response to the operator's instruction to start transmission from the key input device 24, the calling terminal operates the communication control circuit 22.
Connect a line with a communication partner and establish a data link. That is, first, the layers 2 to 4 of the facsimile communication protocol are set (S1). Next, CCIT
Recommendation T. Session start command C defined in 62
SS is sent from the communication control circuit 22 to the called terminal, and a session start acknowledgment R from the called terminal is sent.
Wait for the SSP (S2).

The called terminal outputs a session start acknowledgment RSSP to the calling terminal in response to the CSS from the calling terminal, and waits for the next command (S3).

Upon receiving the RSSP from the called terminal, the calling terminal receives the color space and subsampling ratio table information (table information shown in FIG. 2 in this example) stored in the ROM 10a of the CPU 10. It is read and set in the sample ratio information field of the non-standard function (NSC) parameter of the CDCL command shown in FIG. 4 and transmitted to the called terminal (S4). Then, it waits for a response from the called terminal.

The called terminal is the ROM of its own CPU 10.
The table information of the color space and the sub-sampling ratio (table information shown in FIG. 3 in this description example) stored in 10a is read, and the sample ratio information of the non-standard function (NSC) parameter of the RDCLPL command shown in FIG. Field and send it to the calling terminal (S
5). Then, it waits for a command from the calling terminal.

The calling terminal has information on the color space and the subsampling ratio from the called terminal (in this example, the table information shown in FIG. 3) and information on its own color space and the subsampling ratio (this In the description example, the common information (see FIG. 6) is extracted by comparing the table information shown in FIG. 2 and stored in the RAM 10b of the CPU 10 in a table format. Then, a color space applicable to both the calling side and the called side and its sub-sampling ratio are determined (S6). S
The color space and the sub-sampling ratio determined in step 6 are set in the image encoding / decoding circuit 12, the image to be transmitted is encoded, and output from the communication control circuit 22 to the communication line (S
7).

After the image transmission is completed, the layers 2 to 4 are disconnected or released (S8), and the communication is terminated.

The information shown in FIG. 2 or FIG.
It may be stored electrically or mechanically in a location other than the above. For example, the RAM 10b or a non-volatile memory (not shown) may be used, or a dip switch that can be arbitrarily changed by a user may be used.

The color space used and its subsampling ratio are determined by the NSC of the CSS command and RSSP response.
May be determined.

In the first embodiment described with reference to FIGS. 2 to 7, the applicable color space and sub-sampling ratio can be flexibly determined, and there is an effect that the degree of freedom in determination is high.

Next, the priorities of the color spaces to be used are determined in advance, the color spaces to be used are determined in that order, and the sub-sampling ratio allowed for the determined color space is determined. A second embodiment will be described. The schematic configuration of the second embodiment is the same as that of FIG. 1 in terms of hardware or functional blocks.

In the second embodiment, table information of an allowable or preferable subsampling ratio for each color space that may be used is stored in the ROM 10a of the CPU 10. FIG. 8 shows an example of the sub-sampling ratio table information. In FIG. 8, only the subsampling ratio 1: 1: 1: 1 can be selected for the RGB color space, only the subsampling ratio 1: 1: 1: 1 can be selected for the CMYK color space, and the CIE LAB color space can be selected. 1: 1: 1, 2: 1:
Either 1:11 or 4:11 can be selected, and for the YCrCb color space, any of 1: 1, 2: 1, 2: 1, or 4: 1,: 1 can be selected.

In the second embodiment, as described above, the priorities of the color spaces to be used are registered in advance. Thereby, the preferred color space can be ranked even within the range of the receiving ability. The priority information is stored in the ROM 10a of the CPU 10. FIG. 9 shows an example of the priority order. In FIG. 9, the CMYK color space has the highest priority,
Hereinafter, a CMY color space, an RGB color space, and a CIE LAB color space follow.

Needless to say, the color space and / or the subsampling ratio can be determined by unique values individually representing these, and the unique values are stored in the ROM 10a.

In the second embodiment, the color space and subsampling ratio used in actual image communication
Recommendation T. It is determined by the session start command CSS and the session start acknowledgment RSSP.

FIG. 10 shows the format of the session start command CSS in the second embodiment. As shown in FIG. 10, a CSS command is followed by a plurality of parameters, and a declaration of a receiver priority mode is inserted in its non-standard function (NSC) in addition to a country code, a country code, and a supplier code. I do.

FIG. 11 shows the format of the session start acknowledgment RSSP in the second embodiment. As shown in FIG. 11, a plurality of parameters follow the RSSP response, and priority information is inserted into the non-standard function (NSC) in addition to a country code, a country code, and a supplier code.

In the second embodiment, the CSS command and the RSS
The color space to be used and the subsampling ratio are determined by negotiation using the P response.

FIG. 12 shows a flowchart of image communication according to the second embodiment. In response to the operator's instruction to start transmission by the key input device 24, the calling terminal connects to the line with the communication partner by the communication control circuit 22 and transmits data and data.
Establish a link. That is, first, the layers 2 to 4 of the facsimile communication protocol are set (S11). Next, CCITT Recommendation T. The NSC of the session start command CSS defined in 62 (see FIG. 10) declares the receiver color space priority mode, sends the CSS command to the called terminal, and sends a session start acknowledgment response from the called terminal. It waits for RSSP (S12).

At the called terminal, the CSS from the calling terminal
It is confirmed whether or not the NSC has a declaration of the receiving side color space priority mode (S13). If there is such a declaration, the color space priority information (see FIG. 9) is added to the NSC of the RSSP response (see FIG. 11). It is stored and transmitted to the calling terminal (S1
4) If there is no declaration, RSSP without storing the color space priority information (see FIG. 9) in the NSC of the RSSP response.
Send the response to the calling terminal. After transmitting the RSSP response, the system waits for the next command. Subsequent operations of the called terminal are as usual.

The calling terminal that has received the RSSP response checks whether the NSC of the RSSP response has color space priority information (S15). If there is color space priority information, the calling terminal determines the color space priority information. Is the RAM of the CPU 10
10b and set the mode flag to ON (S1
6).

After S15 or S16, the calling terminal sends a document function list command CDCL as usual to the called terminal, and the called terminal returns a document function list acknowledgment RDCLP.

After receiving the RDCLP response, the calling side terminal refers to the mode flag in the RAM 10b and checks whether or not the terminal is ON (S17). When the mode flag is ON, the color space priority information obtained from the partner terminal (called terminal) is compared with the capability of the own device to determine the color space to be used (S18). For example, a color space having the highest priority at the partner terminal within the capability range of the own device is selected. mode·
When the flag is OFF (S17), the color space to be used is determined only by its own capability (S18).

The color space determined in S17 and S18 is applied to the table shown in FIG. 8, and the subsampling ratio to be used is determined (S20).

The color space thus determined and its sub-sampling ratio are set in the image encoding / decoding circuit 12 to encode the image to be transmitted, and the encoded image data is transmitted to the partner terminal by the document start command CDS. (S21).

After transmitting the necessary image information, the calling terminal transmits a document end command CDE. In response to this, the called terminal returns a document end acknowledgment RDEP. Further, the calling terminal transmits a session termination command CSE, and in response, the called terminal returns a session termination acknowledgment RDEP. Thereafter, the calling terminal disconnects or releases layers 2 to 4 and terminates the display (S22).

In the second embodiment, the information shown in FIG.
It may be stored electrically or mechanically in a location other than 10a. For example, the RAM 10b or a non-volatile memory (not shown) may be used, or a dip switch that can be arbitrarily changed by a user may be used.

In the second embodiment, since the priorities are determined in advance in a color space having a receiving ability, image information can be transmitted in a more preferable color space. In addition, since information on an allowable subsampling ratio for each color space is set in advance, an inappropriate subsampling ratio is not selected for the selected color space, and an appropriate subsampling ratio is always selected. Become like

Next, a third embodiment will be described. This third
In the embodiment, the combination of the encoding method, the sub-sampling ratio, the interleave format, and the color space can be easily selected and determined to be optimal.

FIG. 13 shows an example of a selectable combination of an encoding method, a sub-sampling ratio, an interleave format, and a color space, and FIG. 14 shows another example. The table information having the contents as shown in FIGS.
0 is stored in the ROM 10a. As in the case of FIGS. 2 and 3, the encoding attributes and their choices shown in FIGS. 13 and 14 can be identified by unique values that individually represent each, and the unique values are stored in the ROM 10a.

In the example shown in FIG. 13, the encoding method is C
CITT Recommendation T. JPEG method and CC defined by 81
ITT Recommendation T. The JBIG method defined in 82 can be selected. In the JPEG system, the subsampling ratio is 1:
1: 1, 2: 1: 1 and 4: 1: 1 can be selected, interleave format can be selected from block and plane, and color space can be selected from CIE LAB and YCrCb. J
In the BIG system, the subsampling ratio can be selected from 1: 1: 1 and 2: 1: 1, the interleave format can select only pixels, and the color space can select only RGB.

In the example shown in FIG. 14, J is used as the encoding method.
The PEG method and the JBIG method can be selected. In the JPEG system, the subsampling ratios are 1: 1: 1 and 2: 1: 1.
, The interleave format can select only the block, and the color space can select only CIELAB. J
In the BIG system, only a 1: 1: 1 subsampling ratio can be selected, an interleave format can be selected from pixels and planes, and a color space can be selected from RGB and CIE LAB.

In FIGS. 13 and 14, one or more options are listed for each of the subsampling ratio, the interleave format, and the color space, and any one of them can be selected in relation to the other. In view of the above relationship, it is preferable to list preferred combinations in a limited manner. For example, in FIG. 14, a subsampling ratio of 2: 1: 1 can be selected for the RGB color space in the JBIG system.
As described with reference to FIGS. 2 and 8, the sub-sub pulling ratio is preferably 1: 1: 1 in the RGB space.

The coding attribute used for image communication with the connected partner terminal is described in, for example, CCITT Recommendation T. Document Function List Command at 62 (CDCL)
And document function list positive response (RDCL
P).

FIG. 15 shows the format of the document function list command CDCL in the third embodiment. As shown in FIG. 15, a plurality of parameters follow the CDCL command, and in addition to a country code, a country code, a supplier code, and the like, encoding attribute information is inserted into the non-standard function (NSC). .

FIG. 16 shows the format of the document function list acknowledgment RDCLP in the third embodiment. As shown in FIG. 16, a plurality of parameters follow the RDCLP response, and its non-standard function (NS
In C), encoding attribute information is inserted in addition to the country code, domestic code, supplier code, and the like.

By negotiating the CDCL command and the RDCLP response, coding attributes that can be permitted (or selected) between the terminals are determined. FIG. 17 shows that the calling terminal has the table information shown in FIG.
When the table information shown in FIG. 3 is provided, the table indicates an allowable coding attribute determined by negotiation between terminals, and this information is stored in the RAM 10b of the CPU 10.

In the example shown in FIG. 17, the JPEG encoding method and the JBIG encoding method can be selected. In the JPEG system, only CIE LAB can be selected as a color space, a 1: 1: 1 or 2: 1: 1 subsampling ratio can be selected, and only a block can be selected in an interleave format.
In the JBIG encoding method, only RGB can be selected as a color space, only a 1: 1: 1 subsampling ratio can be selected, and only pixels can be selected in an interleaved format.

FIG. 18 shows a flowchart of image communication according to the third embodiment. Here, ROM1 of the calling terminal is used.
It is assumed that 0a stores the table information shown in FIG. 13, and the ROM 10a of the called terminal stores the table information shown in FIG.

In response to an instruction from the key input device 24 to start transmission by the operator, the calling terminal sets the communication control circuit 22
Connect a line with a communication partner and establish a data link. That is, first, the layers 2 to 4 of the facsimile communication protocol are set (S31). Next, CCI
TT Recommendation T. The communication control circuit 22 sends a session start command CSS defined in 62 to the called terminal, and sends a session start acknowledgment R from the called terminal.
It waits for an SSP (S32).

In response to the CSS from the calling terminal, the called terminal outputs a session start acknowledgment RSSP to the calling terminal and waits for the next command (S3).
3).

Upon receiving the RSSP from the called terminal, the calling terminal reads the encoding attribute information (in this example, the table information shown in FIG. 13) stored in the ROM 10a of the CPU 10, and reads out the coding attribute information shown in FIG. It is set in the encoding attribute field of the non-standard function (NSC) parameter of the indicated CDCL command and transmitted to the called terminal (S3).
4). Then, it waits for a response from the called terminal.

The called terminal is in the ROM of its own CPU 10.
The encoding attribute information (table information shown in FIG. 14 in this example) stored in 10a is read out and set in the encoding attribute information field of the non-standard function (NSC) parameter of the RDCLPL command shown in FIG. Then, the message is transmitted to the calling terminal (S35). Then, it waits for a command from the calling terminal.

The calling terminal sets the encoding attribute information from the called terminal (in this example, the table information shown in FIG. 14).
And the information of the own color space and the subsampling ratio (in this example, the table information shown in FIG. 13), and a common part (see FIG. 17) is extracted and stored in the RAM 10b of the CPU 10 in a table format. Then, an optimal coding attribute applicable to both the calling side and the called side is determined (S36). The encoding attribute determined in S36, that is, the encoding method, the subsampling ratio, the interleave format, and the color space are set in the image encoding / decoding circuit 12, and the image to be transmitted is encoded. Output to the line (S37).

After the image transmission is completed, the layers 2 to 4 are disconnected or released (S38), and the communication is terminated.

The information shown in FIG. 13 or FIG.
It may be stored electrically or mechanically in a location other than 0a. For example, the RAM 10b or a non-volatile memory (not shown) may be used.
It may be a switch or the like.

The encoding attributes used for communication are shown in FIGS.
As in the case of the first embodiment described above, the determination may be made by the NSC of the CSS command and the RSSP response.

As the encoding attribute, in addition to the above, the number of bits of the color component may be incorporated.

In each of the above embodiments, the table of the combination of the color space and the sub-sampling ratio and the table of the combination of the coding method, the interleave format, the color space and the sub-sampling ratio need not have the same contents for transmission and reception. Instead, they may be separate contents.

Although the facsimile communication has been described as an example, it is obvious that the present invention can be used for image communication between computers.

[0081]

As can be easily understood from the above description, according to the present invention, a color image can be transmitted after an appropriate encoding state is set at a higher speed. That is,
There is no need to separately set all encoding attributes (encoding scheme, interleave format, color space, sub-sampling ratio, number of color component bits, etc.) that are assumed as transmitting and receiving terminals. It is possible to transmit and receive image information in various encoding states, and a more flexible system configuration can be realized. For example, addition of a color space that can be handled and its sub-sampling ratio are simplified, and this additional function can be used immediately.

There is also an effect that an appropriate combination is always selected between the encoding attributes. Furthermore, since priority is given to the selectable encoding attribute options, image information can be transmitted / received with more preferable options.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

FIG. 2 is an example of an allowable combination of a color space and a subsampling ratio in the first embodiment.

FIG. 3 is another example of an allowable combination of a color space and a subsampling ratio in the first embodiment.

FIG. 4 shows a format of a CDCL command according to the first embodiment.

FIG. 5 is a format of an RDCLP response according to the first embodiment.

FIG. 6 is an example of a combination of a color space and a sub-sampling ratio allowable between a terminal having the performance shown in FIG. 2 and a terminal having the performance shown in FIG. 3;

FIG. 7 is a flowchart of image communication according to the first embodiment.

FIG. 8 is an example of an allowable combination of a color space and a subsampling ratio in the second embodiment.

FIG. 9 is an example of a priority order of a color space in the second embodiment.

FIG. 10 shows a format of a CSS command according to the second embodiment.

FIG. 11 shows a format of an RSSP response according to the second embodiment.

FIG. 12 is a flowchart of image communication according to the second embodiment.

FIG. 13 is an example of an allowable combination of encoding attributes in the third embodiment.

FIG. 14 is another example of allowable combinations of encoding attributes in the third embodiment.

FIG. 15 shows a format of a CDCL command according to the third embodiment.

FIG. 16 shows an RDCLP response format according to the third embodiment.

17 is an example of a combination of a color space and a sub-sampling ratio that can be permitted between a terminal having the performance shown in FIG. 13 and a terminal having the performance shown in FIG.

FIG. 18 is a flowchart of image communication according to the third embodiment.

[Explanation of symbols]

10: CPU 10a: ROM 10b: RAM 1
2: Image encoding / decoding circuit 14: Image conversion circuit 15: Pixel density conversion circuit 16:
Frame memory 18: DMA control circuit 20: Character generator 22: Communication control circuit 24: Key input device 26: Display device 28: Image scanner 30: Printer 32: I / O control circuit
34: SCSI interface 36: Hard disk 38: Image data bus 40: System bus

Claims (6)

(57) [Claims] (1)Selectable encoding attributes for image encoding
Memorized as a combination of multiple typesStorage means and prior to image transmissionFor encoding attributesReceiving terminal
Confirmation means for confirming communication ability;Said The receiving capability of the receiving terminal confirmed by the confirmation meansSaid
Stored in storage meanssetWhen matching with
Determine the encoding attributes to apply to theGenusGender determining means;Said Transmission with the encoding attribute determined by the attribute determining means
Encoding means for encoding the image to be, And the checking means has priority over the receiving capability of the receiving terminal.
Sends a command including an instruction for ranking, and
Get the priority information included in the response corresponding to the password
And The encoding attribute determining means determines whether the acquired priority information is
Verifies multiple types of combinations stored in the storage unit
And determine the encoding attributes to use Mosquito characterized by
Image transmission device. Wherein the combination of the encoding attribute and comprising a sub-sampling ratio of the color space and image encoding
The image transmission device according to claim 1. (3)Image color space and codes corresponding to the color space
A table storing the sub-sampling ratio at the time of Prior to image transmission, the receiving capability of the receiving terminal regarding the color space
The second is to send a command containing an instruction to determine the priority of the force.
1 transmission means; Sent from the receiving terminal in response to the command
The response contains priority information about the color space
Determining means for determining whether or not It is determined by the determination unit that there is priority information on the color space.
If determined, the priority information on the color space and the previous
Collation with the data in the table above to determine the color space to use
Means for determining a color space, The color space determined by the color space determining means and the table
To determine the sub-sampling ratio.
Sub-sampling ratio determining means; The color space determining means and the sub-sampling ratio determining means
With the color space and subsampling ratio determined by the stage,
Encoding means for encoding an image to be transmitted; A second transmitting the image encoded by the encoding means;
Transmission means, A color image transmission device comprising: 4. A priority for a color space by said determining means.
When it is determined that there is no rank information, the color space determining means
Determines the color space based on the capabilities of the transmitting terminal
The image transmission device according to claim 3, wherein: Claim 5.When encoding images to be transmitted,
Sender terminal that can be selected differently by combining encryption attributes
Image transmission method for transmitting a color image to a receiving terminal
And Prior to image transmission, the receiving terminal receives the encoding attribute.
A confirmation process to confirm your reputation, The receiving capability of the receiving terminal confirmed in the confirmation process and the
Encoding attribute to match with the combination and apply when sending
Attribute determination process for determining The encoding attribute determined in the attribute determination step should be transmitted.
An encoding process for encoding the image In the checking step, the receiving terminal has an excellent reception capability.
Sends a command containing an instruction to determine the priority order, and
Priority information included in the response corresponding to the
Gain In the encoding attribute determination process, the acquired priority information and
Determine the encoding attribute to be used by comparing with the combination
A color image transmission method. 6.Image color space and codes corresponding to the color space
Has a table that stores the sub-sampling ratio and
The color image from the sending terminal to the receiving terminal
An image transmission method, Prior to image transmission, the receiving capability of the receiving terminal regarding the color space
The second is to send a command containing an instruction to determine the priority of the force.
1 transmission process, Sent from the receiving terminal in response to the command
The response contains priority information about the color space
A determination process for determining whether or not Determined that there is priority information on the color space in the determination process
If the color sky Priority information on the
To determine the color space to use
Color space determination process, The color space determined in the color space determination step and the table
Data to determine the sub-sampling ratio.
The process of determining the sampling ratio, The color space determination step and the sub-sampling ratio determination step
In the color space and sub-sampling ratio determined in
An encoding process for encoding the image to be encoded; A second transmission for transmitting the image encoded in the encoding step;
The credit process, A color image transmission method comprising: