JPH0274367A - Modifying method of color and modifying device of color - Google Patents

Abstract

PURPOSE:To obtain an excellent color reproduction characteristic by making calculation with weighting on prescribed input and output colors and by using a coefficient matrix thus obtained. CONSTITUTION:An image processing element 39 comprises an interface 40 for a host receiving an input density digital information as an input, RAM 41 storing each element of a matrix for color correction, image information after a binary-coding processing, etc., ROM 42 storing a plurality of color sample data for determining each element of the matrix, CPU 43, etc. It prepares a duplication of a set of a desired input color digital information on the color sample data and a recording color information. In more detail, it prepares sets [Cin, Min, Yin], [Con, Mom, Yon] of data of (n) = 65 or more from sets [Ci, Mi, Yi], [Co, Mo, Yo] of data and sets of duplications. A weight value is determined by the number of these duplications. As for the data to be weighted, a flesh color being impressionable visually or a color of the highest histogram in a record image is selected automatically or by a keyboard. Subsequently, a coefficient matrix is determined by using the set of the weighted data. According to this method, it is possible to attain complete color correction, i.e. to output a desired record color.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color correction method and a color correction aft for correcting the colors of a color image.

[Prior Art] Conventionally, this type of color correction device approximates in advance the relationship between a recorded color and input density dinotal information for that recorded color using a polynomial, and stores each coefficient of the polynomial function as each element of a matrix. Then, color correction information on the number of recorded colors was obtained using the matrix and the elements of the input density denotational information for each pixel of the color image to be recorded.

An example of the color correction process is shown in the following equation.

However, a+j is each element C, M, Y of the stored matrix
is the input density dinotal information element C', M', Y' of each separated color for one pixel. Due to the unnecessary reflection (absorption) characteristics of the components, the proportional law failure of each recorded color component, and the additive law failure of one reproduced recorded color, the relationship between the recorded color and the input density data is highly nonlinear and has a wide range. There is a problem in that it is extremely difficult to approximate the polynomial function so as to obtain faithful color reproduction characteristics.

The present invention has been made in order to solve the above-mentioned problems, and provides a color correction method and apparatus for color images that can obtain good color reproduction characteristics by performing color correction suitable for the color images to be recorded. The purpose is to provide.

[a! Means for Solving Problem II 1 In order to achieve the above object, the color correction method of the present invention multiplies the first matrix resulting from the input color by a predetermined coefficient matrix, and calculates the color indicated by the second matrix, which is the product of the first matrix. is input into the color transfer system, the coefficients are calculated based on the input color input to the color transfer system and the data of the output color output by the color transfer system when the input color is input. A color correction method for calculating a matrix is characterized in that a coefficient matrix obtained by weighting and calculating predetermined input colors and output colors is used.

Further, as a device for performing this method, the color correction device of the present invention has a calculation means for multiplying a first matrix caused by an input color by a predetermined coefficient matrix and outputting a $2 matrix as the calculation result, In a color correction device that inputs a color indicated by a second matrix outputted by the calculation means to the color transfer system, when the input color input to the color transfer system and the input color are input, the color transfer system a storage means for storing data of an output color to be output; and a coefficient determining means for determining a coefficient matrix to be multiplied by the first matrix in the calculation means by weighting and calculating the data stored in the storage means. It is characterized by having the following.

[Operation 1] In the present invention having the above configuration, a coefficient matrix corresponding to the inverse function of the transfer function of the color transfer system is created using the method of least squares based on the relationship between the input color and the output of the color transfer system. However, this coefficient matrix has a total of n data of input colors and output colors weighted for a predetermined color, and has high color reproducibility for the predetermined color.

[Example 1] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

First, the overall configuration of a color image recording apparatus will be explained with reference to FIGS. 1 and 2. A monochrome laser printer 1 includes a polygon scanner 2 that irradiates laser light, and a photoreceptor that draws an electrostatic latent image using the polygon scanner 2. 3, a developing device 4 for developing the photoreceptor 3 on which an electrostatic latent image has been formed, and an OLIP sheet (OLIP sheet)
The printer is comprised of a cassette 5, a fixing device 6 that fixes the transferred toner image, and monochrome discharge trays 1 and 12 that send out sheets in monochrome mode.

Further, a colorization device 20 that records an image using color separation mask originals created from color image information sends color separation mask originals 22R, 22G, and 22B output from the monochrome laser printer 1 to an exposure unit 36. a y1 device 10a that removably includes a paper bus switching unit 10 that switches the entrance path to supply paper; a photosensitive table 25 that brings the color separation mask original plate 22 into close contact with the photosensitive pressure sensitive paper 24;
A color developer sheet 26 coated with a color developer that develops color by reacting with the dye precursor contained in the microcapsules coated on the surfaces of the three primary colors 21R, 21G, and 21B for exposure and the photosensitive pressure sensitive #v24. a storage section 27 for storing the color developer sheet 26, and a pressure developing means for overlapping the color developer sheet 26 and the photosensitive pressure sensitive paper 24, crushing uncured microcapsules with pressure, and developing an image on the color developer sheet 26. 28, a heat fixing device 29 that promotes color development, a color image output tray 30, a manual feed tray 31 into which the color separation mask master plate 22 is inserted from the outside, and a color separation unit which discharges the exposed color separation mask master plate 22. In FIG. 1, the mask original discharge tray 32, the manual feed tray 33 for the color developer sheet 26, and the input density dinotal f+2 report of the multivalue level for each separated color are subjected to color correction processing, binarization processing, etc. The image processing unit 39 shown in FIG. Incidentally, each member of the optical system, the photosensitive pressure sensitive paper 24, the color developer sheet, etc. of this apparatus correspond to the color transmission system.

The IiI image processing section 39 also has a host interface 40 for inputting multilevel input density digital information for each separated color, each element of a matrix for color correction, image information after binarization processing, etc. A RAM (Random Access Memory) 41 that stores data, a ROM (Read Only Memory) 42 that stores data of a plurality of color samples for determining each element of a matrix for color correction, and a color correction It is composed of a CPU (central processing unit) 43 that performs calculations for processing and binarization processing, and a laser printer interface 44 that sends image information after the binarization processing to the monochrome laser printer 1 for each separated color. There is. The ROM 42 contains music color scheme sample data as follows:
Input concentration dinotal information ECi, , M i, , Y ii
,[Ci,,M i2. Y i21... [C 14th +
M! sn+Y 1641 (collectively [Ci, Mi, Yi
) and its input color [Ci, Mi, Yil are input to this color image recording U device, the recorded lust $1 [C
o + -Mo++Yoit [CO21MO2C02
l]...(Cos<tMos<+Yo,] (also collectively referred to as [Co+Mo, Yol)) A total of 64 data sets are stored. Next, FIGS. 3(a) to #3 The operation of the color image recording apparatus of this embodiment will be explained in accordance with the flowchart shown in FIG. In S2, the CPtJ 43 determines whether the captured information is color mode information, and if it is not color mode information, in step S3, the captured information is directly used using the laser printer interface 44. The information is sent to the monochrome laser printer 1. If the captured information is color mode information, the CPU 43 determines in step S4 whether the captured information is color setting change mode information.

If the loaded information is color setting change mode information, in step S5, input density information and recording color information of a plurality of color sample data are loaded into the CPU 43 from the ROM 42.

Next, the process proceeds to step S6, in which the color sample data taken in in step S5 is weighted.

Specifically, a copy of a set of desired input color digital information and recorded color information of the color sample data is created. In other words, the above 64
The data set ECi, M i, Y il, [co.

The first [c in*M i+++Y in]t[con+M
Create ar++Yonl (where n is a natural number from 1 to N≧65). The weight value is determined by the number of copies. In addition, the data to be weighted is selected automatically or by using a keyboard (not shown), such as visually sensitive skin color or the color with the highest histogram in the recorded image.6 Next, step S7
Proceeding to step S6, a coefficient matrix is determined by the following theory using the data set weighted in step S6.

First, assume the coefficient matrix as follows.

Next, the 64 or more pairs selected in step S6 [
Cin, Min, Y in), ICon, Mon, Yo
Assume the following equation for n).

Create stocks.

If a coefficient determinant satisfying this equation exists for all n, it becomes possible to perform complete color correction, that is, output the desired recording color. However, in general, there is no eight that satisfies this formula. Therefore, use the least squares method to approximate 8. First, rewrite the previous equation as follows to suit the actual situation.

Then, the nth error for use in the least squares method is defined as follows.

En=[(Cin-Cin')"+(Min-Min
)20(Y in Y in' )2] It is sufficient to calculate 8 such that the sum of squares ΣEn2 of all Ens is the minimum.

To this end, in this step, each element to the present coefficient matrix is obtained by first solving the following simultaneous equations for all to a,).

With the above, i$ allows users to reproduce their desired colors with special fidelity! ! The adjustment is completed and the process returns to step S1.

In step S4, if the captured information is not color setting change mode information, in step S9 of FIG. 3(b), the host interface 4
0, input density digital information for each separated color for one pixel is taken into the CPU 43. And step S10
At this point, each element of the color correction matrix stored in the RAM 41 is loaded into the CPU 43. Then, in step S1, the CPU 43 calculates multilevel color correction density dinotal information of the recording separation color number from the input density dinotal information and the color correction matrix using the following formula.

However, C, M, Y are the input density dinotal information of the number of separated colors C', M', Y' are the color correction density dinotal information of the recorded number of separated colors ai'' are each element of the color correction matrix Next, in step S12, A dither threshold value corresponding to the input pixel position of the input density digital information is read into the CPU 43 from the ROM 42, and in step S13, the information of one stored separation color of the color correction density dither information is larger than the one portrait dither threshold value. The CPU 43 determines whether the
In step 51417, the recording dots of the recording separation colors are turned off, and if not, they are turned on in step 51417.

Then, in step S15, the CPU 43 determines whether the process has been performed for all the recorded color separations, so that the steps S12 to S14 are performed for all the recorded color separations.

If this has been done for all color separations, then in step 81G in FIG. Send to laser printer 1. Then, in step S17, the on/off information of recording dots of recording separation colors other than the one recording separation color sent in step 816 is stored in the RAM 4.
Store and store in 1. Then, in step S18,
The CPU 43 determines whether the process has been performed for all pixels of the color image, and if it has not been performed, returns to step S9 so that steps S9 to S17 are performed for all pixels of the color image. do.

After this has been carried out for all pixels of the color image, in step S19 it is determined whether or not the color separation mask original of the previous recorded color separation has been output from the monochrome laser printer, and it waits until it is sent. is step S
At step 20, the remaining one recording color of the recording dot on/off information stored in the RAM 41 is sent to the monochrome laser printer 1 using the laser printer interface 44. In step S21, the CPLI 43 determines whether or not the recording dot on/off information for each recording color stored in all the ff+i RAMs 41 has been processed. This is performed for each recording color stored in the RAM 41.

Further, based on the ON/OFF information of the recording dots of the one recording separation color sent to the monochrome laser printer 1, the polygon scanner 2 irradiates light onto the charged photoreceptor 3 to remove the electrostatic latent. Draw a statue. The photoreceptor 3 on which the electrostatic latent image has been formed is developed by the developer 4, and the toner image is transferred onto plain paper or OHP sheet supplied from the paper feed cassette 5, and fixed by the fixer 6. .

If the output from the monochrome laser printer 1 is not in color mode, the paper path switching unit 10 selects
In the case of color mode, all the sent recording separation colors are outputted to the colorization device r! The information is sequentially sent to I20. (The output paper is printed in the order of output, color separation mask original plate 22R,
22G and 22B. ) The color separation mask original 22R created by the monochrome laser printer 1 passes through the paper switching section 10, and the color separation mask original front end positioning roller 34 determines the front end position of the color separation mask original. The color separation mask original plate 22R is connected to an insulating color separation mask original transport means 35 (for example, PET) which is routed around the circumference in order to transport the color separation mask original plate, and a static electricity generating device 3 such as a Flotron or the like.
Electrostatically pasted using 8, exposed 2 nits 3
6. The color separation mask original 22R is moved by moving the color separation mask original transport means 35.
Positioning is performed so that color shift does not occur in the color latent image formed on the photosensitive pressure sensitive paper 24. In the exposure unit 36, the color separation mask original 22R and the photosensitive pressure sensitive paper 24 are brought into close contact with each other by the exposure table 25, and the light source 21
By being exposed to red light for a certain period of time, a latent image composed of uncured cyan microcapsules is formed for each pixel corresponding to the color separation mask original 22R.

After exposure, the color separation mask original 22R is discharged to the color separation mask original discharge tray 32.

The same process is performed for the color separation mask originals 22G and 22B, thereby forming a color latent image on the photosensitive pressure sensitive paper 24.

The exposed light-sensitive and pressure-sensitive paper 24 is exposed to the color developer sheet 2.
6 and is developed by the pressure developing means 28.

The color developer sheet is then applied to the heat fixing device! ! 29 and is discharged to the color image discharge tray 30. The used photosensitive and pressure sensitive paper 24 that has been subjected to pressure development is wound up by a winding means 37.

The present invention is not limited to the embodiments described in detail above, and various changes can be made without departing from the spirit thereof.

For example, in this embodiment, the image processing section 39 is incorporated in the colorization device 20, but it may be installed as a separate and independent device from the Moeki colorization device fi 20 or inside the monochrome laser printer 1.

[Effect of the Invention 1] As is clear from the detailed description above, according to the present invention, sufficient color correction is performed at least for a predetermined color. Therefore, compared to the conventional type, visually superior color correction can be performed with a smaller amount of calculation.

Therefore, by using the present invention, it becomes possible to form and transmit visually excellent images with less processing time.

[Brief explanation of the drawing]

The drawings show an embodiment embodying the present invention, and FIG. 1 shows image processing of a color image recording wave jn to which this embodiment is applied! I! FIG. 3A is a schematic block diagram of the color image recording device, and FIG.
c) is a 70-chart diagram showing the treatment contents of the image processing unit. In the figure, 42 is a ROM corresponding to the storage means, S6 and S7 are processing steps corresponding to the coefficient matrix determining means, and Sll is a processing step corresponding to the calculation means. ost 1st drawing, B, P

Claims (1)

[Scope of Claims] 1. Used in a color transfer system that outputs an output color corresponding to the input color by inputting information about the input color, wherein a predetermined coefficient matrix is added to the first matrix resulting from the input color. A method of inputting color information indicated by a second matrix, which is the product thereof, into the color transfer system, the method comprising: inputting the input color input to the color transfer system and the input color; A color correction method for calculating the coefficient matrix based on data of output colors output by the system, characterized in that a coefficient matrix obtained by weighting and calculating predetermined input colors and output colors is used. Color correction method. 2. By inputting input color information, it is used in a color transfer system that outputs an output color corresponding to the input color, and the first matrix resulting from the input color is multiplied by a predetermined coefficient matrix, and the calculation result is In the color correction device, the color correction device has a calculation means for outputting a second matrix, and inputs the color indicated by the second matrix outputted by the calculation means to the color transfer system, wherein the input color input to the color transfer system is and a storage means for storing data of an output color outputted by the color transfer system when the input color is inputted; and by weighting and calculating the data stored in the storage means, A color correction device comprising: coefficient matrix determining means for determining a coefficient matrix by which the first matrix is multiplied.