JPH0437364A - Printer - Google Patents

Abstract

PURPOSE:To print out a picture in which color is reproduced constant even when the picture is printed out on any color paper by correcting the color reproduction depending on the color of print paper. CONSTITUTION:At application of power current to a printer main body 1, sets of color information RP, GP, BP of print paper in a paper supply cassette are obtained from a color sensor 6 and the relation of RP'=(255-RP), GP'=(255-GP), and BP'=(255-BP) is set respectively to correction coefficient areas 7a,7b,7c. Then a data is received from a host computer 2 and stored in a reception buffer 4 and a data by one unit code is read from the stored buffer 4. Whether or not a data command is a print instruction or a paper discharge instruction is discriminated. In the case of the print instruction, usual print processing is implemented to decide RGB quantities RO, GO, BO to be allocated to each picture element. Then RGB quantities RS, GS, BS after correction are calculated according to the relation of RS=RO-RP', GS=GO-GP', BS=BO-BP'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing device, and particularly to a printing device capable of printing a plurality of colors.

[Prior Art] Conventional printing apparatuses always reproduce the same color regardless of the color of the paper being printed, if the input data is the same.

[Problems to be Solved by the Invention] However, there is a drawback that when the color of the paper to be printed changes, color reproduction varies due to the influence of the color of the paper.

For example, if you print on yellowish paper, the entire printed image will appear yellowish, and if you print on bluish paper, the entire printed image will appear bluish.

The present invention eliminates the conventional drawbacks and provides a printing device that reproduces a constant image even if the color of paper to be printed changes.

[Means for Solving the Problem] In order to solve this problem, the printing apparatus of the present invention includes a color recognition means for recognizing the color of paper to be printed, and a reproduction color corresponding to the recognized color of the paper. and color correction means for correcting.

[Operation] In this configuration, by correcting color reproduction depending on the color of paper to be printed, it is possible to print an image with constant color reproduction no matter what color of paper it is printed on.

[Example] Hereinafter, an example according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a printing apparatus according to this embodiment. In the example, red, green, blue (RGB)
A YMCK printing device that prints input image information in yellow, magenta, cyan, and black (YMCK) will be explained.

In FIG. 1, an external host computer 2 is connected to the main body l of the YMCK printing device indicated by a broken line through a connector (not shown), and receives and receives commands, data, etc. from the host computer 2. It is configured so that it can be printed out. Calculations that perform all control within the main body 1
The control CPU 3 includes a reception buffer 4 that temporarily stores received data such as commands and data from the host computer 2, a ROM 5 that stores programs, etc. for executing a series of control flows described later, and a print A color sensor 6 that recognizes the color of paper to be printed, a RAM 7 that functions as a work area when the CPU 3 executes a program, and an output unit 8 that outputs color image data using YMCK.
and a power supply device (not shown) are connected. Also, R.A.
Within the MT, there are areas 7a, 7 for storing RGB color correction coefficients according to the color of paper to be printed recognized by the color sensor 6.
b, 7c are secured.

Next, regarding the operation of the YMCK printing device shown in FIG.
The explanation will be given according to the flowchart shown in the figure.

In FIG. 2, when power is first supplied to the main body 1, color information Rp, Gp, Bp of the paper to be printed in the paper feed cassette is obtained from the color sensor 6 in step S1, and Rp' = (255-RP ) Gp'=(255-Gp)B and '=(255-BP) are set in the correction coefficient areas 7a, 7b, and 7c, respectively.

Next, in step S2, data is received from the host computer 2 and stored in the reception buffer 4, and data for one unit code is read from the stored reception buffer 4. In step S3, it is determined whether the data command is a print command or a paper discharge command.

If it is a print command, normal print processing is performed in step S4, and the RGB values Ro, Go, and RGB values to be assigned to the pixels are determined.
Determine Bo. Then, in step $5, R,=R,-R.

Gs=G0-G.

BS = BO-B.

Then, the corrected RGB values Rfi, G, , B are calculated. In step S6, by logarithmic transformation, RGB-YMC
Conversion is performed, and MMC is converted by masking in step s7.
is corrected, and in step S8, YM is removed by undercolor removal processing.
C-YMCK conversion is performed, and YMCK is further corrected by gamma conversion in step S9. The YMCK values obtained in step 510 are binarized using the dither method or error diffusion method, and developed into a YMCK bitmap, and step S2
Return to

On the other hand, if it is determined in step S3 that it is a paper discharge command, the YMCK bit map is transferred to the output unit 8 and printed/discharged in step Sll.

Since the paper in the paper feed cassette is new, the process returns to step S1 and the process starts again from acquiring color information of the paper in the paper feed cassette.

In this embodiment, the color of the paper was recognized by the color sensor 6 on the paper cassette, but it may also be done by human input from a panel or the like, or the color of the paper may be changed for each paper cassette. The paper cassette may be recognized by a mark or the like placed on the paper cassette. Alternatively, the color of the paper may be recognized by a command from the host computer.

Furthermore, although a YMCK printing device was used in this embodiment, it may be a YMC printing device or any other multicolor printing device.Also, color correction may be performed using YMC other than RGB.

There is no need to use YMCK, HSB, HVC, etc.

The color correction method is not limited to this embodiment, and may be performed at any time, such as logarithmic conversion, masking, undercolor removal, and gamma conversion.

Further, the correction may be performed by hardware instead of software, and in this case, the processing speed is further improved.

Furthermore, color recognition may be performed not every time a sheet is ejected as in this embodiment, but when replacing a cassette or when specified by a command.

That is, any type of color recognition may be used as long as the correction is completed during the printing operation.

As explained above, by correcting color reproduction according to the color of the paper to be printed on, no matter what color the paper is printed on,
This has the effect of always providing the same color reproduction image.

[Effects of the Invention] According to the present invention, it is possible to provide a printing device that reproduces a constant image even if the color of paper to be printed changes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the printing apparatus of this embodiment, and FIG. 2 is a flowchart showing the operating procedure of the printing apparatus of this embodiment. In the figure, 1...Printing device body, 2...Host computer, 3...CPU, 4...Reception buffer, 5...
・ROM, 6...Color sensor, 7...RAM, 7a・
...R correction coefficient area, 7b...G correction coefficient area, 7c
. . . B correction coefficient area, 8 . . . output section.

Claims (1)

[Scope of Claims] A printing apparatus comprising: color recognition means for recognizing the color of paper to be printed; and color correction means for correcting reproduced colors in accordance with the recognized color of the paper.