JPS6392166A - Image forming device - Google Patents

Abstract

PURPOSE:To improve picture quality by selecting and determining a color correction coefficient according to humidity as information correlative to characteristics of a color material. CONSTITUTION:A humidity detection part 21 detects the humidity and compares the detected humidity with plural predetermined reference values to decide which range the counted value is in, thereby outputting the result. A color correction coefficient determination part 23 receives the decision result from the detection part 21 and selects a color correction coefficient corresponding to the decision result among plural predetermined color correction coefficients to determine 8 color correction coefficient corresponding to the humidity, thereby outputting it to a color correction part 24. Thus, the color correction coefficient is selected and determined according to the humidity as the information correlative to the characteristics of the color material, so even if the color material changes in its characteristics owing to variation in humidity, an excellent image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image forming apparatus capable of forming color images.

2. Description of the Related Art In general, there are various image forming apparatuses capable of forming color images, such as color copying machines and color printing apparatuses.

In such an image forming apparatus, for example, cyan (C)
), magenta (M), and yellow (Y) color materials (toner or ink) are used to form a color image.

By the way, 5. For example, yellow (Y) coloring material contains some magenta (M) and cyan (C) components.
The color of the coloring material is not necessarily red (R).

Green (G), Blue (B) or Cyan (C).

It does not match the manual color data for magenta (M) and yellow (Y). Therefore, the input data is converted as shown in the following equation to determine the amount of each color material.

In this formula, C, M, and Y are the dot area ratios of cyan, magenta, and yellow, and are 01 to C34M.

~M3. Y1 to Yl are color correction coefficients, and R, G, and B are respective densities of red, green, and blue.

However, in conventional image forming apparatuses, the color correction coefficients are fixed values, so even if the amount of each coloring material is determined as described above, good images may not be obtained due to atmospheric humidity, etc. There is an inconvenience.

Purpose This invention has been made in view of the above points, and an object thereof is to improve image quality.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention determines color correction coefficients based on information correlated to the characteristics of coloring materials.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a control section of an image forming apparatus embodying the present invention.

The host 1 is, for example, a personal computer, a word processor, a data processor, an image editing processing system, a workstation, etc., and transfers the character code or bit data (hereinafter referred to as "image data") of a created image to the image forming apparatus 2. Note that image data read by the image reading device 1 is transferred to the image forming device 2.
It can also be transferred to.

The image data transferred from this host 1 is red (R).
), green (G), and blue (B) color attributes are added. Note that instead of red (R), green (G), and blue (B), the color attributes may be yellow (Y), magenta (M), and cyan (C,).

The controller 3 receives the image data sent from the host 1, develops the character code into a bit map, and converts the character code into a red (R).

Green (G) and blue (B) data are subjected to color correction processing and converted into yellow (Y), magenta (M), and cyan (C) data, and then yellow (Y).

Each magenta (M), cyan (CC,) data is written to the page memory 4 where the data is located.

As shown in FIG.
Y), magenta (M), cyan (C).

Black (K) or yellow (Y), magenta (M),
For each color of cyan (C), n memories each having a capacity for one page are provided in accordance with the number of gradations (2 to the nth power gradation).

The arithmetic processor 5 reads the data written in the page memory 4 and performs various filtering processes such as edge emphasis and smoothing, enlarging/reducing one-turn processing, OCR (undercolor removal) processing, dither processing, etc. Various types of processing are performed (it is not necessary to perform all of these processings), and the processed data is written to the page memory 4 again.

The engine controller 6 reads data from the page memory 4 and creates signals at timings that match the printer engine 7. The printer engine 7 is, for example, an electrophotographic device or a thermal printer.

This is a printer engine such as an inkjet printer.

FIG. 4 is a block diagram showing a portion of controller B related to color correction.

As mentioned above, color correction refers to red as image data (
R), green (G), and blue (B) data to appropriate cyan (C) and magenta (M) according to the coloring materials used.
, yellow (Y), and in this case cyan (C).

Each of magenta (M) and yellow (Y) is red (
It can be expressed as a polynomial of R), green (G), and blue (B) as shown in the following equation.

C=f1 (R, G, B) M=f2 (R, G, B) Y=f3 (R, G, B) In this case, fl, f2. f3 is obtained by measuring the color density of the actual coloring material and approximating it from the data group of the actual measurement values.

Therefore, in order to realize this color correction, calculations can be performed using software, but in order to increase the processing speed, a ROM is used here to create a table.

In other words, ROMII has red (R) and green (G).
, blue (B) data to cyan (C) data, and the ROM 12 stores red (R) and green (G) data.

A table for converting blue (B) data to magenta (M) data is stored, and the ROM 13 also stores red (R), green (G), and blue (B) data as yellow (Y) data. Contains a table for converting to .

In addition, multiple types of tables are created with different color correction coefficients depending on the number of prints, that is, for example, four types of tables with color correction coefficients A, B, C, and D are created and RO
It is stored in M, 11-13.

Then, each address terminal A of these ROM1i to 13
4-bit red (R) data in O to A3, 4-bit green (G) data in address terminals A4 to A7,
4-bit blue (B) data is applied to each of the address terminals A8 to All as address data.

Further, a humidity detector 14 that detects humidity as information correlated to the characteristics of the coloring material, and a fifth
It is equipped with an A/D converter 15 that A/D converts the output voltage output with the humidity-output voltage characteristic shown in the figure, and the 2-bit data from this A/D converter 15 is stored in the ROM 11.
As table switching data forming a part of the address data of ~13, "0° OJ, ro, IJ, 'rl', OJ ', rl, H, the table of color correction coefficient A is changed to ro, OJ, the table of color correction coefficient B is changed to r'o, 4 J, and the color correction coefficient is changed to rl, 'OJ. It is assumed that when the table of C is rl and the table of H is selected, the table of color correction coefficients is selected.

FIG. 1 is a block diagram functionally showing a portion related to color correction in a control section of this image forming apparatus.

The humidity detection unit 21 detects humidity, compares the detected humidity with a plurality of predetermined reference values, determines within which range the counted value falls, and outputs the determination result. Note that, in reality, as described above, the humidity detection result is A/D converted to generate the determination result.゛The color correction coefficient determination unit 23 receives the determination result from the humidity detection unit 21, selects a color correction coefficient according to the determination result from among a plurality of predetermined color correction coefficients, and selects a color according to the humidity. A correction coefficient is determined, and the determined color correction coefficient is output.

The color correction unit 24 is a color image data, for example, red (R).
, green (G), and blue (B) data are subjected to color correction processing using the color correction coefficients received from the color correction coefficient determination unit 23 to produce yellow (Y), magenta (M), and cyan (C) data. Output the converted color output data.

Next, the operation of this embodiment configured as described above will be explained with reference to FIGS. 6 and 7.

First, the flow of processing of the control section of this image forming apparatus will be explained with reference to FIG.

The red (R), green (G), and blue (B) data input from the host 1 side to the input interface (I/F) are enlarged, reduced, and rotated as necessary (this process is a color correction process). Red (R) after this treatment.

Color correction processing is performed on green (G) and blue (B) data to produce yellow (Y) and magenta (M).

Convert to cyan (C) data.

After that, yellow (Y) obtained by this color correction,
U based on magenta (M) and cyan (C) data
Yellow (Y) after CR treatment.

Convert to magenta (M), cyan (C), and black (K) data, and apply edge enhancement, smoothing, etc. to this yellow (Y), magenta (M), cyan (C), and black (K) data. After various filter processing, it is binarized,
It is sent to the printer engine via the engine interface (1/F).

Next, one-color correction processing will be explained with reference to FIG.

In this color correction process, depending on the detected humidity, for example, if the humidity is 40% or less, coefficient A is set as the color correction coefficient, and if the humidity exceeds 40% and is 60% or less, coefficient B is set as the color correction coefficient. If the humidity is over 60% and below 80%, set coefficient C as the color correction coefficient, and if the humidity exceeds 80%, set coefficient C as the color correction coefficient, and then set this set color correction coefficient. Perform color correction calculations based on

Although this process is an example of performing color correction using software, it can also be performed using hardware using a table as described above, so this point will be explained below.

In this case, if the humidity is 40% or less, table switching data ro and OJ are given to ROM11 to 13, and the humidity is 40% or less.
If it is more than 0% and less than 60%, table cut MA day'l
ro, 1" to ROM11-13, humidity is 60%
If it exceeds 80% or less, table switching data rl, O
J is given to ROM11-13, and when the humidity exceeds 80%, table switching data N,11 is given to ROM11-13, so each table in ROM11-13 is switched, so the color correction coefficient according to the detected humidity is applied. Color correction is performed.

In this way, in this image forming apparatus, the color correction coefficient is selected and determined according to the humidity, which is information that correlates with the characteristics of the coloring material, so that even if the characteristics of the coloring material change due to changes in humidity, A good image can be obtained.

In addition, in the above embodiment, an example was described in which humidity was used as information correlated to the characteristics of the coloring material, but other information such as temperature may also be used.

As explained above, according to the present invention, image quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram functionally showing parts related to color correction in an embodiment of the present invention. FIG. 2 is a block diagram showing a control section of an image forming apparatus embodying the present invention. Figures 3, 4 and 5 are block diagrams showing the configuration of the page memory and the configuration of the nine-color correction unit, and a diagram showing the output characteristics of the humidity detector, and Figure 6 is the same image forming process. FIG. 3 is a block diagram for explaining the flow of the process. FIG. 7 is a flow diagram similarly showing the color correction process. 1...Host 2...Image forming device 3...
・Controller 4...Page memory 5...f
iW processor 6...engine controller 7...
・Printer engine 11-13...ROM14...
・Humidity detector 15...A/D converter 23...Color correction coefficient determining section 24...Color correction section Fig. 1 Tsum Fig. 2 Fig. 3

Claims (1)

[Scope of Claims] 1. An image forming apparatus capable of forming a color image, characterized by comprising a color correction coefficient determination unit that determines a color correction coefficient based on information correlated to the characteristics of a coloring material. Device. 2. The image forming apparatus according to claim 1, wherein the color correction coefficient determining means determines the color correction coefficient according to humidity.