JPS631498Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color conversion circuit used in a color facsimile device.

Various recording methods for color facsimile devices have been proposed in the past, one of which is a color inkjet method. This method uses the three primary colors of subtractive mixing: yellow, magenta, and cyan.
Color recording is performed by spraying colored ink droplets onto recording paper and combining the three colors.

By the way, a color facsimile device's original function is to perform color recording that is faithful to the original document, so for example, if the background color of the document is red, this background color itself has no effect. Even if there is no meaning, and only the letters and figures written on it are important, the background color of the calligraphy and drawings reproduced on the receiving side will be red. This is not desirable in terms of the clarity of the reproduced calligraphy and images, and especially in the case of the above-mentioned inkjet recording, it wastes ink, and furthermore, the recording paper becomes sticky with ink and becomes difficult to handle. This results in problems.

In view of this, the present invention is designed to replace a specific color such as the background color of a document with white for transmission.The details will be explained below with reference to the drawings.

FIG. 1 shows a schematic configuration of an embodiment of a color conversion circuit according to the present invention. In the same figure, Y, M,
C is each component of a color image signal derived from the document reading means, separated into the three primary colors of yellow, magenta, and cyan, and then binarized; 3 Match detection circuit 2
Y, 2M, and 2C are given as one input each, and on the other hand, they are given as one input each of the first to third AND gates 4Y, 4M, and 4C.

On the other hand, 1Y, 1M, and 1C are all composed of a combination of switches and flip-flops, and are first to third color setting circuits that set and store yellow, magenta, and cyan, respectively, and the output of each circuit is The first to third coincidence detection circuits 2Y, 2M, 2
It is designed to be given as each other input of C. Therefore, for example, if the background color of the original is red and this red is to be replaced with white for transmission, as can be seen from Figure 2, R (red) = Y (yellow) + M (magenta). , and sets the first and second setting circuits 1Y and 1M. As a result, the respective inputs of one of the first to third coincidence detection circuits 2Y, 2M, and 2C become 1, 1, and 0 in this order (1 represents a high level and 0 represents a low level, respectively).

Therefore, when the three primary color signals Y, M, and C become 1, 1, and 0 representing red, the first to third
The outputs of the coincidence detection circuits 2Y, 2M, and 2C all become 1, indicating a coincidence state. Therefore, the output of the NAND gate 3 with each of these outputs as three inputs is 0,
As a result, the first to third AND gates 4Y, 4
The outputs of M and 4C are all 0, representing white,
This signal representing white is introduced into the next transmission processing circuit 5.

The transmission processing circuit 5 is composed of a combination of a memo corresponding to each input of yellow, magenta, and cyan, and a microprocessor that controls the writing and reading of the memo, and converts the three primary color signals introduced simultaneously into sequential signals. Therefore, when the previous white signal is introduced, it is transmitted as a 3-bit serial signal (000). It should be noted that this transmission processing circuit 5 may be implemented in various ways other than the above, but since they are not related to the gist of the present invention, their explanation will be omitted.

Further, when the three primary color signals Y, M, and C represent a color other than red, and when none of the first to third setting circuits 1Y, 1M, and 1C are set, 1 to 3rd coincidence detection circuit 2Y, 2
The outputs of M and 2C are all 1 only when the three primary color signals Y, M, and C become 0, 0, 0 representing white. Therefore, in other cases, the output of the NAND gate 3 is always 1, and as a result, the first to third AND gates 4Y, 4M, and 4C are all open, so that the signals Y, M, and C are is directly introduced into the transmission processing circuit 5. Therefore, the original color information is faithfully transmitted.

The illustrated embodiment is intended for the case where color recording is performed using a total of 8 colors, including 7 colors not including halftones shown in FIG. However, the present invention can also be applied to analog signals or multi-level digital signals.

Since the color conversion circuit of the present invention is configured as described above, it is possible to replace a specific color of a color image signal to be transmitted with white and transmit it. This method is suitable for transmitting a document with characters written on it, and is highly effective when implemented in a color facsimile device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a color conversion circuit according to the present invention, and FIG. 2 is a diagram showing a color combination relationship for the purpose of explaining the same. Y, M, C...color image signal, 1Y, 1M, 1
C...color setting circuit, 2Y, 2M, 2C...coincidence detection circuit, 5...transmission processing circuit.

Claims (1)

[Scope of utility model registration request] In a color facsimile device that transmits a color image signal that has been separated into three primary colors and then binarized, there is a means for specifying and storing a specific background color of a document in advance, and an output and an input of the means. A color facsimile machine comprising: means for detecting a match in color with a color image signal obtained by the color image signal; and means for obtaining a matching output from the means and controlling the color represented by the color image signal to be replaced with white and transmitted. Color conversion circuit of the device.