JPH02205175A - Method and equipment for transmitting color image - Google Patents

Abstract

PURPOSE:To obtain a color picture transmitter to shorten a transmission time by suitably determining the number of lines for each block, and compressing the data quantity of digital image data by a two-dimensional redundancy suppressing encoding system. CONSTITUTION:The digital image data in a C color are read from a frame memory 7 for the number of lines in one block and encoded. After that, the data are outputted to a digital line 3. When it is finished to output one block in the C color to the line, the digital picture data in an M color are read only for the block, encoded and outputted to the digital line 3. Samely, the digital image data in Y color and BK color are successively encoded for one block and outputted to the digital line 3. Since the two-dimensional redundancy suppressing encoding system is adopted for encoding the digital image data, the data quantity is compressed and the transmission time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the transmission of color images such as color photographs;
In particular, methods for transmitting color images using digital lines,
The present invention relates to a color image transmitting device.

2. Description of the Related Art Conventionally, a common method for transmitting color images such as color photographs has been to separate color images and transmit color image data for each color in a line-sequential manner using an analog line.

An example of a conventional technique related to such color image transmission is a line-sequential color facsimile transmission/reception system disclosed in Japanese Patent Application Laid-Open No. 48-96223.

Problems to be Solved by the Invention However, high-speed transmission is not possible with such a transmission method using an analog line, and it is necessary to use a digital line for higher-speed transmission.

Now, in order to efficiently transmit color images using a digital line, it is necessary to compress the amount of transmitted data by performing redundancy reduction encoding on the color image data on the transmitting side. However, in the line sequential method, a two-dimensional redundancy suppression coding method with good compression efficiency cannot be applied, and there is a limit to the improvement of transmission efficiency.

For more efficient transmission, on the transmitting side, the color-separated color image data is stored in memory, and the digital image data of each color is encoded with redundancy reduction and divided into frames (areas). One possible method is to send the data to a digital line using a sequential method. According to this method, it is possible to employ a two-dimensional redundancy suppression encoding method with good compression efficiency, so it is possible to improve transmission efficiency more than in the case of a line sequential method.

FIG. 4(a) shows the timing of image data input and line output according to this method. Here, color images are cyan (C), magenta (M), yellow (M), and black (
BK) and input the image data of all colors at the same time.
Only the cyan image data is output to the line while it is being input, and then the MlYlBK image data is sequentially output to the next line frame by frame.

Note that if the memory for storing image data cannot be written and read at the same time, the output of the image data of C will start after the input is completed, so the end of the line output will be delayed by the color frame from the time shown in the figure. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a color image transmission method using a digital line, which can further reduce transmission time than the above-described frame-sequential color image transmission method, and a color image transmission apparatus therefor.

Means for Solving the Problems In order to solve the above-mentioned problems, the color image transmission method of the present invention involves simultaneously inputting digital image data for each color obtained by separating a color image into the transmitting device, and starting the input. Immediately after, the input digital image data is subjected to redundancy suppression coding for each color in block units consisting of multiple lines in order, and sent to the digital line, and in the receiving device,
This apparatus is configured to restore digital image data of a color image by sequentially receiving and decoding encoded data of each color from the digital line.

In addition, in order to carry out this method, the color image transmitting device of the present invention includes means for simultaneously inputting digital image data for each color obtained by separating a color image for all colors, and digital image data input by this input means. Immediately after the start of the input operation by the input means,
The apparatus further comprises means for sequentially applying redundancy suppression coding to the digital image data stored in the storage means for each color in block units consisting of a plurality of lines, and transmitting the encoded data to a digital line.

According to the above-described transmission method and transmitting device of the present invention, the number of lines per block is appropriately determined, and the amount of digital image data is sufficiently compressed using a two-dimensional redundancy suppression coding method. By shortening the transmission time sufficiently, it is possible to output most of the color image data over the line while inputting the digital image data, so the transmission time including the input time of the color image can be It can be much shorter than the sequential method.

Embodiment FIG. 1 is a schematic configuration diagram of a color image transmission system according to an embodiment of the present invention, in which 1 is a transmitting device, 2 is a receiving device, and 3 is a digital line.

In the transmitting device 1, 5 is a color scanner that separates and reads a color image and simultaneously inputs analog image data of each color of C, M, Y, and BK as separate analog signals. Reference numeral 6 denotes an analog/digital converter for converting the analog image data input from the color scanner 5 into digital image data.
There are several. 7 is a frame memory for storing digital image data of each color. 8 is an encoding device that encodes the digital image data of each color using a two-dimensional redundancy suppression encoding method and compresses the amount of data; 9 outputs the encoded data of the digital image data to the digital line 3;
It is also a line output device that exchanges messages with the receiving device 2 through the digital line 3. IO is a control device that controls the operation of each device within the transmitter and the transmission sequence.

Note that the color scanner 5 may be a unit independent from the transmitting device. In this case, the analog/digital converter 6 may belong to the color scanner 5 unit.

In the receiving device 2, a line input device 11 receives encoded data from the digital line 3 and exchanges messages with the transmitting device 1 through the digital line 3. 1
2 is a decoding device for decoding received encoded data to restore digital image data; 13 is a frame memory for storing the restored digital image data. 14
is a recording device that records digital image data as a color image.

Reference numeral 15 denotes a control device that controls each device within the receiving device and controls the receiving sequence.

Note that the recording device 14 may be a unit independent from the receiving device.

The operation of the color image transmission system configured as described above will be explained below.

First, the operation of the transmitting device 1 will be explained. Reading of a color image by the color scanner 5 is started, and analog image data of each color is input at the same time, converted into digital image data by the analog/digital converter 6, and stored in the frame memory 7 sequentially.

Immediately after this input starts, six-color digital image data corresponding to the number of lines in l block are sequentially read out from the frame memory 7, encoded by the encoding device 8, and then output from the line output device 9 to the digital line 3. be done. When the line output of one block of six colors is completed, one block of M-color digital image data is sequentially read out from the frame memory 7, encoded, and output to the digital line 3. Similarly, one block of Y color and BK color digital image data is sequentially encoded and sent to the digital line 3. B
When one block of K color is output to the line, the next block of digital image data of each of the six colors is sequentially encoded and output to the line again.

FIG. 2 shows how digital image data of each color is output on a line in units of blocks.

Here, the number of lines in the l block is three. The digital image data of each color is arranged and stored in the frame memory 7 in the order of line number as shown in the figure, and the 1st, 2nd, and 3rd lines of each color are treated as the 1st block, and C, M, Y, BK are stored. The blocks are transmitted sequentially, and then the fourth, fifth, and sixth lines are transmitted in the same manner as the second block.

Such writing and reading of frame memory 7 is controlled by control device IO.

Note that the frame memory 7 may be divided into frame areas for different colors, and digital image data of each color may be continuously stored in the corresponding frame areas. Furthermore, the number of lines in one block is not limited to three.

Now, to encode digital image data, it is possible to adopt a two-dimensional redundancy reduction encoding method such as the MR method, which has good compression efficiency, so the amount of data can be sufficiently compressed and the time required to transmit each block can be reduced. It can be shortened sufficiently.

Therefore, most of the line output can be completed while color image data is being input, so (b) in Figure 4 can be completed.
), the line output can be terminated immediately after the input of the color-specific data of the color image is completed.

Next, the operation of the transmitter 2 will be explained. The encoded data of each color is sequentially sent to the digital line 3 in block units from the transmitting device 1, and is sequentially received by the line input device 11.
The data is decoded by the decoding device 12 and returned to digital image data before encoding. The restored digital image data of each color is sequentially stored in the frame memory 13. The digital image data stored in the frame memory 13 is transferred to the recording device 14 and recorded immediately after the start of reception or when an instruction is given from outside.

FIG. 3 shows how the encoded data of each color is received and decoded. The encoded data of each color received in blocks (3 lines) in the order of C, M, Y, BK is restored to 3 lines of digital image data and stored in the frame memo January 3.

Note that the frame memory 13 may be divided into frame areas for each color, and the restored digital image data of each color may be continuously stored in the corresponding frame areas.

Effects of the Invention As is clear from the above explanation, the present invention allows digital image data for each color obtained by color separation of a color image to be inputted simultaneously for all colors, and immediately after the start of this inputting, a plurality of inputted digital image data are inputted. By sequentially applying redundancy suppression coding to each color in block units consisting of lines and sending it to the digital line, the transmission time including the input time of color image data can be reduced compared to the conventional method using analog lines and the digital line. Of course, this method has the effect that it can be dramatically shortened compared to the line sequential method used, and it can also be significantly shortened compared to the field sequential transmission method using the above-mentioned digital line.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a color image transmission system according to an embodiment of the present invention, Figure 2 is a diagram showing how image data is encoded and line output, and Figure 3 is a diagram showing how encoded data is received and restored. FIG. 4 is a diagram showing a comparison of the timing of image data input and line output in the frame sequential transmission method and the transmission method of the present invention. DESCRIPTION OF SYMBOLS 1... Transmitting device, 2... Receiving device, 3... Digital line, 5... Color scanner 6... Analog/digital converter, 7... Frame memory, 8...
Encoding device, 9... Line output device, 11... Line input device, 12... Decoding device, 13... Frame memory, 14... Recording device.

Claims (2)

[Claims] (1) In the transmitting device, digital image data for each color obtained by separating the color image is input for all colors at the same time, and immediately after the start of this input, the input digital image data is sequentially input for each color in blocks consisting of multiple lines. It is subjected to redundancy suppression encoding and sent to a digital line, and at the receiving device,
A method for transmitting a color image, characterized in that digital image data of a color image is restored by sequentially receiving and decoding encoded data of each color from the digital line. (2) means for simultaneously inputting digital image data for each color obtained by separating a color image for all colors; means for temporarily storing the digital image data inputted by the input means; Immediately after the start, the digital image data stored in the storage means is sequentially subjected to redundancy suppression coding for each color in block units consisting of a plurality of lines, and then sent to a digital line. Transmitting device.