JP3036790B2 - Color image processing apparatus and method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a color image processing apparatus and method for creating color correction data used when performing color correction according to observation environment light when observing an output image. About.

[Prior Art] Conventionally, the color reproducibility of a color printer changes with aging, exchange of toner materials, environmental fluctuation, printing medium, light source color temperature for viewing, etc., and adjustment is performed manually each time. I was

[Problems to be Solved by the Invention] However, in the above conventional example, since the adjustment is complicated, there are the following defects.

1) Adjustment requires specialized knowledge, and it is difficult for ordinary users to make adjustments, so maintenance by dedicated service is required.

2) A hard copy that matches the viewing environment (color temperature of the light source, etc.) cannot be obtained.

3) The operating rate decreases.

4) Hard copy quality varies widely.

5) Since the service is required, the running cost increases.

6) Since the serviceman's subjectivity is included, there is large variation between devices.

7) The load of the adjustment process at the time of production is large, and the cost is increased.

8) The degree of freedom for changing the toner material is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to obtain an output image that matches the observation environment light when observing the output image.

Means for Solving the Problems In order to achieve the above object, the present invention provides a test pattern data generating means for generating test pattern data, and observing an output image based on a test image output based on the test pattern data. Input means for irradiating with light corresponding to the observation environment light at the time and inputting read data obtained by reading, and observation environment light for observing the output image based on the read data and the test pattern data. And color correction means for performing color correction on input color image data based on the generated color correction data.

Also, the present invention is a color image processing method for creating color correction data used when performing color correction according to the observation environment light when observing an output image, wherein a test image is used for observing the output image. Irradiation with light equivalent to the observation environment light of
Inputting read data obtained by reading, based on the input read data and the data indicating the test image, generating color correction data according to observation environment light when observing the output image. Features.

[Operation] According to the present invention, the test image is irradiated with light corresponding to the observation environment light when observing the output image, and the color correction data is generated based on the read data. , Color correction is performed on the input color image data.

FIG. 1 shows an embodiment of the present invention. The description will be made on the example of the electrophotographic method, but the same applies to other methods.

The operation of the printer includes a normal mode and a test mode. In the normal mode, the switch SW is connected to the terminal 1. Y (yellow), M (magenta), C (cyan)
The image signal composed of the three primary colors is input to the gradation correction circuit 2 via the host I / F 1 and the switch SW, and is subjected to gradation correction, then color correction by the color correction circuit 3, and then to recording by the recording conversion circuit 4. The data is converted as appropriate, and then supplied to a laser emission / scanner 6 via a laser driver 5, where it is converted into a laser beam, reflected by a mirror 7, and scanned and exposed on a photosensitive drum 8 to form a latent image. I do. The latent image on the photosensitive drum 8 is developed with each color (Y, M, C) toner in the toner cartridge 9 supplied via the developing sleeve 10, transferred to the printing paper 12 by the transfer drum 11, and To settle. 14 is a charger and 15 is a cleaner.

 The above operation is the same as the conventional operation.

In test mode, switch SW is connected to terminal 2,
The test signal from the test signal generation circuit 16 is input to the gradation correction circuit 2. After the gradation correction circuit 2 until fixing by the fixing device 13 is the same as described above. After passing through the fixing device 13, the printing paper is subjected to a correction filter 18 by a first optical fiber 17.
The light from the light source 19, which is in the same state as under the light source for observing the printed image after correcting by the above, is radiated, and the reflected light of the printing paper is sent to the optical detector circuit 21 by the second optical fiber 20, where the light is reflected. The signal levels of R (red), G (green), and B (blue) are measured. Actually, an electric signal is obtained by a photodiode via a color filter. The signal from the detector circuit 21 is amplified by an amplifier 22 and converted to a digital signal by an analog / digital converter (ADC) 23.
Input to the comparator 24. Data from the expected value memory 25 is input to the other side of the comparator 24. The memory 25 stores the gradation correction circuit 2 from the test signal generation circuit 16.
, The R / G / B expected signal corresponding to the Y / M / C signal given to is stored. The difference ε between the expected value and the measured value is calculated by the comparator 24.
And sends it to the correction amount generating circuit 26, where a correction value is generated and input to the gradation correction circuit 2 and the color correction circuit 3. The processing procedure in the gradation correction circuit 2 is as follows.

y = x ^γ (1) where y: output signal x: input signal γ: gradation correction value In the color correction circuit 3, Here, Y, M, C: output signal Y ', M', C ': input signal ai: color correction value This process is repeated until the difference ε becomes equal to or less than the specified value. Since the temperature of the fixing unit 13 is as high as about 160 ° C., heat is isolated using an optical fiber.
In addition, since the positions of the light detector circuit 21 and the light source 19 can be freely selected, design is easy.

FIG. 2 shows a printing pattern on printing paper in the test mode. This sets the comparator 24 to a test signal generation circuit
Start pattern,
It is composed of three patterns: a test pattern and a stop pattern. Here, the start pattern is a solid black line,
Stop pattern is black of two lines, the test pattern T ₁ ~
It was a constant band of color consisting of T _N.

When the test pattern signal from the ADC 23 is received, the operation of the comparator 24 is started. Subsequently, the test pattern signal is compared with the expected value of the memory 25. When the stop pattern is received, the operation is stopped, and the difference ε is corrected. It is input to the quantity generation circuit 26. The correction amount generation circuit 26 determines which test pattern is the difference ε based on the signal from the test signal generation circuit 16, and determines the correction amount from a series of values of the difference ε.

The correction amount of the correction amount generation circuit 26 may be increment / decrement without changing the absolute value.

Further, the optical fiber may be scanned using the test pattern shown in FIG. 3, or a plurality of optical fibers may be used.

If the number of test patterns is too large to fit on one printing sheet, a stop pattern may be inserted at the end of a plurality of sheets.

In the test mode, the switch SW is switched to 2 automatically after a specified time set in the timer 27 or when the power is turned off and then when the power is first turned on. Also, when the toner cartridge is replaced, the switch SW is switched to 2 to automatically start. In addition, a message indicating that the paper is a test paper is written on the test printing paper in order to identify a hard copy in a normal state. The paper is also discharged to a designated bin (eg, at the bottom) of the stacker 28 to prevent mixing with other hard copies.

[Effects of the Invention] As described above, according to the present invention, a test image is irradiated with light corresponding to observation environment light when observing an output image, and color correction data is generated based on the read data. Therefore, it is possible to generate color correction data according to the observation environment light.

Therefore, by performing color correction using the color correction data generated by the present invention, it is possible to obtain an output image that matches the viewing environment.

[Brief description of the drawings]

 FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a diagram showing an example of a test pattern, and FIG. 3 is a diagram showing another example of a test pattern. 17,20 ... optical fiber, 24 ... comparator, 26 ... correction amount generation circuit.

Continuation of the front page (56) References JP-A-4-28555 (JP, A) JP-A-4-28549 (JP, A) JP-A-63-185279 (JP, A) JP-A-64-41375 (JP) , A) Actual opening 1979-96112 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46-1/62 B41J 3/00 B41J 5/30 G06T 1/00

Claims (2)

(57) [Claims] A test pattern data generating means for generating test pattern data; and irradiating and reading a test image output based on the test pattern data with light corresponding to observation environment light when observing the output image. Input means for inputting the obtained read data, generating means for generating, based on the read data and the test pattern data, color correction data according to observation environment light when observing the output image; A color correction unit configured to perform color correction on the input color image data based on the generated color correction data. 2. A color image processing method for creating color correction data used when performing color correction according to observation environment light when observing an output image, comprising: Irradiation with light corresponding to the observation environment light, and input read data obtained by reading, based on the input read data and data indicating the test image, observation environment light when observing the output image A color image processing method for generating color correction data according to the image data.