JPS59135975A - Coding and decoding system of color signal - Google Patents

Abstract

PURPOSE:To attain efficient compression of a color signal by using a color library in a color facsimile so as to give a short code to a color having a high utilizing frequency and a long code to a color having a low frequency. CONSTITUTION:An electric signal corresponding to R, G, B is obtained by lighting alternately three-color light source at a photoelectric converting/color separating circuit 1. The color library 2 is utilized and the color code is decided by a color deciding circuit 3. Since a short code to the color having high frequency of use and a long code to the color having a low frequency of use are given respectively, efficient compression is attained with a simple method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field to which the invention pertains) The present invention relates to a highly efficient color signal encoding/decoding system used in 1D color 7 axis IJ and the like.

(Prior art) In the past, color hook stains 1.1 were often made of two colors (for example, black and red), but recently, with the development of color separation technology and multicolor recording technology such as inkjet, color hook stains 1.1 have been made in seven colors. Multicolor or full color (natural color)
facsimile is now possible. However, if normal facsimile transmission means is used for these documents having multiple colors, there is a drawback that the transmission time is extremely long.

In other words, R (red), G (green), and B (
When obtaining and transmitting a color signal (blue), the amount of information for each pixel is 4 x 3 = 12b, assuming that the gradation is 4 bits.
It is 12 times as large as the black and white binary value. Simple band compression means such as MW (modified Huffman), MR
(Modified read) has the drawback that in the case of black-and-white binary data, a transmission that could be done in one minute takes an extremely long time of 12 minutes, making it impractical.

(Objective of the Invention) In order to eliminate these drawbacks, the present invention provides an encoding/decoding method that efficiently compresses color signals and aims to shorten the transmission time. Explain.

(Structure and operation of the invention) FIG. 1 is a block diagram showing the structure of a transmission system according to an embodiment of the invention, in which 1 is a photoelectric conversion/color separation circuit, for example, three colors (R
, G, B) The light sources are turned on alternately to obtain electrical signals corresponding to R2O,B. 2 is a color library in which a color determination circuit 3 determines the sign of the color.

Figure 2 shows the configuration of color library 2.The code structure is based on color manuscripts and statistical properties, and short codes are assigned to colors that are used frequently, and long codes are assigned to colors that are used less frequently. Sumurateru. For example, black is placed first and green is placed second, but this color library needs to have similar color libraries for the transmission and reception systems in advance.

Next, 4 is a color change detection circuit, and 5 is a run length counter, which counts the number of colors of the same length obtained by the color change detection circuit 4.The run length encoder 6 converts the value to a run length table 7, for example. Encode using MH code or the like.

FIG. 3 shows an example of a code string output from the run-length encoding device 6 of FIG. 1, which is composed of a color code and a run-length code for that color.

On the receiving side (contrary to this method, the color signal of each pixel is decoded and sent to the signal recording system. In the recording system, a color mixing method corresponding to the color signal is set in advance, and recording is performed based on this. For example, in the case of an inkjet method, the amount of ink should be determined according to the color signal.Also, in the case of the density pattern method, it is sufficient to determine the relationship between the arrangement of color pixels and color mixture in relation to the color signal in advance. , for example, 1 for a 4×4 density pattern
Can be specified using several color signals.

In this case, a fixed color library is used, but the code may be changed depending on the color used, for example. This takes advantage of the fact that in the case of color, there is a very strong correlation between adjacent pixels, lines, or regions. Therefore, −
Since there is a strong possibility that a color that changes frequency will appear many times, a short code may be specified for the first color used, for example.

(Effects) As explained above, the present invention has 1. color life library
Since it is possible to realize a highly efficient encoding/decoding system using a simple method, it has the advantage that it can be applied to various image communication fields such as color facsimile IJ for high-speed transmission.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a transmission system according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a color life library, and FIG. 3 is a diagram showing an example of a code string. 1...Photoelectric conversion/color separation circuit, 2...Song...color library, 3...Color determination circuit, 4...Color change detection circuit , 5...
・・・・・・Run length counter, 6・・・・・・
...Run length encoding device, 7...
Run length table. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a transmission system such as a facsimile, a signal composed of multiple colors and color-separated by photoelectric conversion of the next original is compared with a color library that stores code strings corresponding to color signals in advance, and the corresponding signal is In the receiving system, the color signal obtained by decoding is transmitted to the pixel corresponding to the transmitting side. or a code for a color signal characterized by having means for recording a group of pixels;
Decryption method. (2) The color library according to claim (1), wherein the color library assigns short signals to colors that are frequently used and long codes to colors that are less frequently used, and can be sequentially rewritten. Signal encoding/decoding method.