JPH06245228A - Color code conversion method between input and output device - Google Patents

Abstract

PURPOSE:To realize the conversion of color codes between input and output devices at a low cost in which no unnatural sense is caused to a human visual sense by specifying a valid bit digit number and an extracted position. CONSTITUTION:A converter 5 converts R.G.B data of a CPU 1 into Y.M.C.K data of a printer 4. The converter 5 detects maximum data among entered R.G.B data at first, and extracts a predetermined number of bits below a most significant bit of the maximum value data and stores the location of the most significant bit, then extracts a predetermined number of bits below a most significant bit of other color data and sets a shift quantity of the conversion table in response to the most significant bit. Thus, the Y.M.C.K codes corresponding to the codes of the valid bit are retrieved based on the selected conversion table and an obtained color code is printed out by a printer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color code conversion method between input / output devices, and more particularly to a color code conversion method capable of increasing the economical efficiency of storage capacity in conversion processing.

[0002]

2. Description of the Related Art In the color output of a CPU, the three primary colors are generally represented by R, G and B for the convenience of driving a CRT display. On the other hand, the color expression of a color printer using toner or ink is generally Y (yellow = yellow) · M.
(Magenta = red), C (cyan = blue), and K (black). Therefore, in order to output the input data from the CPU to the color printer, it is necessary to convert the expression data unique to the output device.

As a method of converting this proper expression, a method of using a conversion formula such as a matrix operation is known.
Particularly in the case of a single-transfer type laser beam printer, since the unique expression is irregular and complicated, it is difficult to convert it by an arithmetic expression.

Therefore, as a conversion method capable of coping with complicated color conversion, there is a method of using a table in which correspondences of all colors are described.

[0005]

[Problems to be Solved by the Invention] However, R, G, B
In the case of full color using an 8-bit code for each color, the total is about 16.7 million colors, so Y ・ M ・ C ・
To store the conversion table for K, a storage capacity of 64 MB or more is required. This is too huge,
It is hard to say that it is realistic in terms of cost.

Therefore, as a practical measure, it is conceivable that the effective input data is limited to 5 to 6 bits by discarding 2 to 3 bits from the smallest one for each color.

In reality, however, human vision has an exponential response characteristic, and therefore, by omitting these 2 to 3 bits, the color tone of the original data is significantly different. There is.

The present invention has been devised in order to eliminate such inconveniences of the prior art, and its main purpose is to provide a color between input / output devices that does not cause human vision to feel unnatural. It is to provide a color code conversion method that can realize code conversion at a relatively low cost.

[0009]

According to the present invention, there is provided a color code conversion method for converting normalized input data into proper expression data of an output device.
By extracting a preset number of bits from the most significant bit in the input data, and searching a preset data table corresponding to the position of the extracted bit in the bits of the input data, The present invention is achieved by providing a color code conversion method between input / output devices, which is characterized by converting input data into the unique expression data.

[0010]

According to such a structure, even if the number of effective bits of the color code on the input device side is reduced, a large change in color tone is not caused. Therefore, the storage capacity for the table for converting to the proper representation of the output device can be significantly reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to specific embodiments shown in the accompanying drawings.

FIG. 1 is a schematic block diagram of a CAD system to which the present invention is applied. This system is a CPU
1, a keyboard 2 for operating the same, a CRT display 3 for visually displaying the operation status, and a C
It comprises a printer 4 for printing out the input data from the PU 1 and a conversion device 5 for converting the R, G, B data of the CPU 1 into the Y, M, C, K data of the printer 4.

Next, the flow of conversion of R, G, B data into Y, M, C, K data will be described with reference to FIG.

First, R / G /
The maximum value data of the B data is detected (step 2). If, for example, the following data is obtained, the bit 765433210 R 00100000 G 0000101 01 B 00000011 R has 5 bits as the most significant, G has 3 bits as the most significant, and B has 1
The bit is the most significant, and in this example R has the maximum value data.

Next, below the most significant bit of the maximum value data,
Extract a predetermined number (eg 5) of bits (step 3),
And the most significant bit position is stored (step 4). In this case, the valid data is in the range of bit 5 to bit 1 with bit 5 as the most significant bit.

Next, for the other color data (G and B), a predetermined number (5) of bits corresponding to the most significant bit or less stored in step 4 are extracted (step 5). By aligning this for each color, the following 5-bit code is obtained. R --- 10000- G --00100- B --00001-

Next, the shift amount of the conversion table is set according to the most significant bit (step 6). In this case, the data shift amount is 1.

The conversion table selected in this manner is searched for Y, M, C, K codes corresponding to the effective bit code (step 7), and the color code thus obtained is output to the printer ( Step 8).

Since the original data is 8 bits, if 5 bits of the original data are extracted, this 5-bit data group will be shifted in 4 steps among the 8-bit data.

On the other hand, if each color of R, G, and B is expressed by 5 bits, the total is about 32,000 colors, but if the shift amount in the original data of the extracted data group is added to this, the total is calculated. If about 128,000 colors are set in the table, the gradation of 8-bit data will not be lost. It also has about 3 well-trained human identifiable colors.
Since it is said to be all colors, it is possible to cover almost all practical colors.

If the basic concept of the present invention is applied to the case where a signal of a CPU having a large number of colors is output to a display having a low color resolution, it is possible to make the expression in a non-saturated range relatively unnatural. Therefore, it can be applied to a code conversion device that does not include conversion into Y, M, C, and K.

When applied to a synthesizer for digitizing sounds, it is possible to reduce the storage capacity required for setting the relationship between frequency band and timbre.

[0023]

As described above, according to the present invention, the scale of the conversion table is reduced and the conversion error is conspicuous by properly setting the number of digits and the extraction position of the bits that are effective when the color code is converted. It can be lost. Therefore,
A great effect can be achieved in reducing the storage capacity and constructing an economical code conversion system.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of the present invention.

FIG. 2 is a flow chart related to conversion.

[Explanation of symbols]

 1 CPU 2 keyboard 3 CRT display 4 printer 5 converter

Claims (1)

[Claims] 1. A color code conversion method for converting normalized input data into proper expression data of an output device, wherein a predetermined number of bits are extracted from the highest bit in the input data, Between the input / output devices characterized in that the input data is converted into the unique expression data by searching a preset data table corresponding to the position of the extracted bit occupying within the bits of the input data. Color code conversion method.