JPH02158277A - Color image processor - Google Patents

Abstract

PURPOSE:To improve the operability of color balance adjustment by adjusting color balance in an RGB state before converting signals of red(R), green(G), and blue(B) into recording colors of yellow(Y), magenta(M), cyan(C), and black (K). CONSTITUTION:Digital data of R, G, and B are supplied to a density conversion part 16, which converts 8-bit data into 6-bit data while a density adjusting circuit 20 adjusts the color balance by the colors. Then the output data of R, G, and B from the density conversion part 16 are applied to a color reproduction part 23, which generates 6-bit data of Y, M, C, and K. Thus, the color balance is adjusted in the RGB state before the signals of R, G, and B are converted into Y, M, C, and K, so the adjustment of the color balance is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color image processing device, and more specifically,
The present invention relates to a color image processing device with excellent operability in color balance adjustment.

(Background of the invention) Red R1 Green G for color images such as character drawings and photographic images.

It is divided into blue B and optically read, and this is yellow Y.

There is a color image processing apparatus that converts the image into a recording color such as magenta M, cyan C1 and black, and records the image on a recording paper using an output device such as an electrophotographic color copying machine based on the converted recording color.

By the way, when performing color balance adjustment in such a color image processing device, the color balance adjustment is generally performed at the Y, M, and C stages immediately before the image output device (printer). .

FIG. 3 shows a schematic configuration of such a color image processing apparatus. In this figure, reference numeral 1 denotes a scanner unit that optically reads a document image and outputs it as digital data for each RGB. A color reproduction section 2 converts the read RGB data into YMCK data of the color of the recorded toner. Reference numeral 3 indicates a color balance adjustment unit that adjusts the density of YMCK data for each color to adjust color balance, and 4 a printer unit that forms an image according to the YMCK data that has undergone color balance adjustment. In the color balance adjustment of such a color image processing apparatus, the color balance is adjusted by increasing or decreasing the density of each color of Y, M, and C.

(Problem to be solved by the invention) When color balance adjustment is performed using the above device,
Since there is no one-to-one correspondence between the read RGB and the output YMCK, there is a problem in that it is difficult for the operator to get a feel for color balance adjustment. Also, the printer Y
Since the gradation characteristics of each MCK color are not uniform and the characteristics themselves are complicated, there is also the problem that adjustment operations are not easy.

The present invention has been made in view of the above problems, and an object thereof is to realize a color image processing device in which color balance can be easily adjusted.

(Means for Solving the Problems) The present invention for solving the above problems includes a color balance adjustment means for adjusting the color balance of a digital color signal given from the outside, and a digital color signal whose color balance has been adjusted by the color balance adjustment means. The apparatus is characterized in that it has a color reproduction means for converting the color signal into a plurality of digital recorded color signals corresponding to the recorded colors of toner for forming a color image.

(Function) In the color image processing apparatus of the present invention, the digital color signal is subjected to color balance adjustment by the color balance adjustment means before being subjected to color correction. Thereafter, the signal is converted into a color signal of the recording toner by color reproduction processing.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention.

In the figure, 11 optically reads the original image, RGB
This is a scanner unit that includes an image reading section and an A/D converter in order to output each image as 8-bit digital data. 12 is an image reading unit for optically reading the original image; 13 is an A/D converter that converts the red image signal read by the image reading unit 12 into 8-bit digital data; and 14 is the image reading unit 12. An A/D converter 15 converts the green image signal read by the image reading section 12 into 8-bit digital data, and 15 an A/D converter that converts the blue image signal read by the image reading section 12 into 8-bit digital data. It is a vessel.

Reference numeral 16 denotes a density conversion section that converts the RGB 8-bit digital data from the scanner unit 11 into 6-bit data. 17 is an R density conversion unit that converts red 8-bit digital data into 6-bit digital data while adjusting density; 18 is a G density conversion unit that converts green 8-bit digital data into 6-bit digital data while adjusting density. Section 19 is a B density conversion section which converts blue 8-bit digital data into 6-bit digital data while adjusting the density. 20 is a density adjustment circuit for adjusting color balance.

This density adjustment circuit 20 is for adjusting the color balance for each color. 21 is color code processing 1
This is a color reproduction table that performs color reproduction and monochrome processing.

22 receives data from the R, G, and B density converters;
This is a color code processing unit that discriminates between white/black/color and outputs a color code. 23 receives the RGB data from the R, G, B density conversion section and converts Y, M, C
, K is a color reproduction unit that generates data of K. Reference numeral 24 denotes a monocolor processing section that receives data from the density adjustment circuit 20 and performs monocolor processing (achromatic colors such as black characters). 25
are Y, M, each 6 bits according to the color code.
This is a selector for selecting one of C, K, and monochrome data. 26 is an EE circuit for performing automatic density adjustment (EE), 27 is a color ghost correction section for performing color ghost correction, 28 is a main scanning direction color ghost detection section for detecting color ghosts in the main scanning direction, 29 30 is a sub-scanning direction color ghost detection unit that detects color ghosts in the sub-scanning direction; 30 is a memory for temporarily storing data of a plurality of pixels for color ghost correction; 31
32 is a filter processing unit that performs filter processing on the density signal; 33 is a scaling process; the shaded area is a scaling/shading processing unit that performs processing; 34 is a processing unit that performs processing; PWM multi-value converting unit that multi-values a 6-bit density signal by pulse width modulation (PWM), 35
is Y.

This printer unit forms a color image by sequentially overlapping M, C, and M toner images. 3
Reference numeral 6 denotes a color balance adjustment operation section for performing color balance adjustment operations.

The original image is read by an image reading section 12 and converted into analog signals for each RGB, and these analog signals are converted into 8-bit digital data by an A/D converter for each pixel. The R, G, and B digital data are then supplied to the density conversion section. In the density conversion section, the 8-bit data is converted into 6-bit data with the color balance adjusted by the density adjustment circuit 20 for each color. That is, in each density conversion section, the output levels of RGB are adjusted in accordance with instructions from the density adjustment circuit 20 based on operations from the color balance adjustment operation section 36. The output data of the RGB density conversion section is applied to the color code processing section 21 and the color reproduction section 23. On the other hand, the color code processing section outputs a color code indicating which color region (white, black, or color) each pixel belongs to, based on the level of each R, G, and B data.

The color reproduction unit 23 also performs color correction (R, G, B-Y, M,
C) and undercolor removal (Y, M, CY, M.

C, K) are performed simultaneously using a correspondence table (lookup table) to create data of 6 bits each for YMCK.

Furthermore, the monocolor processing section 24 creates 6-bit monocolor (achromatic color) data from the output data of the A/D converter 14. The selector 25 selects and outputs YMCK or monochrome data one color at a time according to the color code and a scan code according to the rotation of the photosensitive drum of the printer unit 35. Thereafter, color ghost removal, scaling, halftone dotting, and multi-value conversion are performed, and the printer unit 35 performs image formation.

In this printer unit 35, Y, M, and C toner images are sequentially superimposed on a photosensitive drum, and then transferred to a transfer paper.

As described above, before converting RGB signals to YMCK, color balance adjustment is performed while RGB remains unchanged. Since the RGB data linearly corresponds to the RGB density of the original image, the color balance adjustment is directly reflected in the output color. Therefore, the color balance adjustment operation and the change in output color correspond well. Furthermore, unlike when adjusting in the YMCK state, it is not affected by the complicated gradation characteristics of the printer. Therefore, the color balance adjustment operation can be easily performed.

Next, the configuration and operation of each part of a color copying machine to which the color image processing apparatus of the present invention is applied will be explained with reference to FIG. Note that this color copying machine uses a color dry development method. In this example, two-component non-contact development and reversal development are employed.

In other words, the transfer drum used in conventional color image formation is not used, and the images are superimposed on the electrophotographic photosensitive drum that forms the image. In addition, in the following example, in order to downsize the device, four-color images of yellow, magenta, cyan, and black are developed on an OPC photoreceptor (drum) for image formation by four rotations of the drum, and then transferred after development. The image is transferred once to recording paper such as plain paper.

By turning on the copy button of the color copying machine, the original reading section A is driven. And the manuscript table 128
An original 101 is optically scanned by an optical system.

This optical system uses a light source such as a halogen lamp at 129° and 130°.
and a carriage 132 provided with a reflective mirror 131.
It is composed of a movable mirror unit 134 provided with V mirrors 133 and 133'.

The carriage 132 and the movable unit 134 are caused to travel on a slide rail 136 at predetermined speeds and directions, respectively, by a stepping motor 135.

Optical information (image information) obtained by irradiating the original 101 with light sources 129 and 130 is transmitted to the reflecting mirror 131 and the mirror 1.
33.133', optical information conversion unit 137
guided by.

There is a standard white plate 1 on the back side of the left end of the platen glass 128.
38 are provided. This is because the image signal is normalized to a white signal by optically scanning the standard white plate 138.

The optical information conversion unit 137 includes a lens 139, a prism 140, two dichroic mirrors 102 and 103, a C0D 104 for capturing a red color-separated image, a CCD 105 for capturing a green color-separated image, and a blue color-separated image. It is composed of a CCD 106 to be imaged.

The optical signal obtained by the optical system is collected by the lens 139, and separated into blue optical information and yellow optical information by the dichroic mirror 102 provided in the prism 140 described above. Furthermore, dichroic mirror 103
The yellow optical information is color-separated into red optical information and green optical information.

In this way, the color optical image is decomposed by the prism 140 into three-color optical information of red, R, green, and blue.

Each color separation image is formed on the light receiving surface of each CCD, thereby obtaining an image signal converted into an electrical signal.

After the image signal is processed by the signal processing system, each color signal is output to the writing section B.

As shown in FIG. 1, the signal processing system includes various signal processing circuits such as an A/D converter, a color reproduction table, a color ghost correction section, and a PWM multilevel conversion section.

The writing section B has a deflector 141. As this deflector 141, in addition to a galvanometer mirror, a rotating polygon mirror, etc.
A deflector consisting of an optical deflector using crystal or the like may be used. The laser beam modulated by the color signal is deflected and scanned by this deflector 141.

When deflection scanning is started, beam scanning is detected by a laser beam index sensor (not shown), and beam modulation using a first color signal (for example, a yellow signal) is started. The modulated beam is applied to an image forming body (photosensitive drum) to which a charge of 7,- is applied by a charger 154.
142J-.

Here, the main scanning by the laser beam and the image forming body 142 are performed.
Due to the sub-scanning caused by the rotation of the image forming member 142, an electrostatic latent image corresponding to the first color signal is formed on the image forming body 142.

This electrostatic latent image is transferred to a developing device 14 containing yellow toner.
3 to form a yellow toner image.

Note that a predetermined developing bias voltage from a high voltage source is applied to this developing device.

Toner replenishment for the developing unit is done by the CPU for system control.
A toner replenishing means (not shown) is controlled based on a command signal from a toner replenishing means (not shown), so that toner is replenished when necessary. The yellow toner image described above is rotated with the cleaning blade 147a released from pressure, and an electrostatic latent image is formed based on a second color signal (for example, a magenta signal) in the same manner as in the case of the first color signal. .

Then, by using a developing device 144 containing magenta toner, this is developed to form a magenta toner image.

Needless to say, a predetermined developing bias voltage is applied to the developing unit 144 from a high voltage power supply.

Similarly, an electrostatic latent image is formed based on the third color signal (cyan signal), and a developing device 145 containing cyan toner is provided.
A cyan toner image is formed. Further, an electrostatic latent image is formed based on the fourth color signal (black signal), and is developed in the same manner as the previous time using the developing device 146 filled with black toner.

Therefore, multicolor toner images are formed on the image forming body 142 in an overlapping manner.

Although the formation of a four-color multicolor toner image has been described here, it goes without saying that a two-color or single-color toner image can be formed.

As described above, the development process is a so-called non-contact two-component development process in which each toner is ejected toward the image forming body 142 while AC and DC bias voltages from a high-voltage power source are applied. An example of jumping development is shown.

Toner replenishment to the developing devices 143, 144, 145, and 146 is performed based on a command signal from the CPU as described above, and a predetermined amount of toner is replenished.

On the other hand, the recording paper P fed from the paper feeding device 148 via the feed roll 149 and the timing roll 150 is conveyed onto the surface of the image forming body 142 in a state in which the timing is synchronized with the rotation of the image forming body 142. Ru. Then, the multicolor toner image is transferred onto the recording paper P by the transfer pole 151 to which a high voltage is applied from the high voltage power source, and the separation pole 152
separated by

The separated recording paper P is conveyed to the fixing device 153, where it undergoes a fixing process and a color image is obtained.

The image forming body 142 after the transfer is transferred to a cleaning device 147
is cleaned and prepared for the next imaging process.

In the cleaning device 147, a predetermined DC voltage is applied to the metal roll 147b in order to facilitate recovery of the toner cleaned by the cleaning blade 147a. This metal roll 147b is placed on the surface of the image forming body 142 in a non-contact state. cleaning blade 1
47a is released from pressure bonding after cleaning is completed, but in order to release unnecessary toner that is left behind at the time of release, an auxiliary roller 147C is further provided, and this auxiliary roller 147c is rotated in the opposite direction to the image forming body 142 and is pressed against the image forming member 142. As a result, unnecessary toner is sufficiently cleaned and removed.

Although the description has been made regarding a color copying machine, it goes without saying that the color image processing apparatus of the present invention can be used in various other devices that process color images.

(Effects of the Invention) As described above in detail, in the present invention, before converting RGB signals to YMCK, color balance adjustment is performed while RGB signals remain. Therefore, the feeling of the color balance adjustment operation corresponds to the actual change in output color.

Therefore, it is possible to realize a color image processing device in which the color balance can be easily adjusted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention, FIG. 2 is a block diagram showing the overall structure of a color copying machine, and FIG. 3 is a block diagram showing the schematic structure of a conventional color image processing device. be. 11...Scanner unit 12...Image reading section 13.14.15...A/D converter 16...Density conversion section 17...R density conversion section 1
8...G concentration conversion section 19...Ba variation conversion 20
... Density adjustment circuit 21 ... Color reproduction table 22
... Color code processing section 23 ... Color reproduction section 24 ... Monochrome processing section 25 ... Selector 26 ... EE circuit 27
...Color ghost correction section 28...Two color ghost detection sections in the main scanning direction...
Sub-scanning direction color ghost detection section 30...memory 31...color ghost removal section 32...filter processing section 33...magnification/shading processing section 34...PWM multilevel conversion section 35...・Printer unit 36...Color balance adjustment operation section

Claims (1)

[Claims] A color balance adjustment means for adjusting the color balance of a digital color signal given from the outside, and a plurality of digital signals according to the recorded color of toner for color image formation from the digital color signal whose color balance has been adjusted by the color balance adjustment means. 1. A color image processing device comprising: color reproduction means for converting into recorded color signals.