Calibration data preparing system

Details Calibration data preparing system Calibration data preparing system

2000-03-24

2004-10-12

Lee, Thomas D. (Department: 2624)

Facsimile and static presentation processing

Static presentation processing

Attribute control

C358S504000, C358S518000

Reexamination Certificate

active

06804025

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tone characteristic data preparing system for preparing tone characteristic data such as calibration data.
2. Description of Related Art
In conventional printing systems that are capable of performing relatively high-quality multi-level tone printing, color calibration is performed to allow density levels obtained on a printed matter produced by a printer to properly match input density levels that are included in image data originally supplied from an upper mark or superior program, such as an application program.
SUMMARY OF THE INVENTION
It is conceivable to prepare tone characteristic data or calibration data using a procedure described below.
It is now assumed that a printer is designed to be capable of performing color printing using four colors of ink, that is, cyan (C), magenta (M), yellow (Y), and black (K) ink, and to be capable of printing images in multi-level tones, 256 total tone levels, for example, for each color. During the calibration data preparing operation, the printer is controlled to produce a test chart by printing a plurality of color patches as shown in FIG.
1
.
As shown in
FIG. 1
, each color patch is a pattern in an optional shape (square shape in this example) whose inner area is completely printed to a uniform tone. The color patches are printed in four rows, one row for each of the colors of cyan (C), magenta (M), yellow (Y), and black (K). In this example, each row includes nine color patches aligned in the row. The nine patches in each row are printed with nine different output tone levels that are separated by about 32 levels each, that is, 0, 32, 64, 96, 128, 160, 192, 224, and 255 respectively. These values of output levels are applied to the printer to print the patches.
Next, the tone level of each printed patch is measured by a colorimeter, for example. A correspondence relationship between input tone levels, supplied to the printer, and the output tone levels, obtained by the colorimeter, is obtained. Other output tone levels that correspond to input levels that are not actually supplied to the printer, are calculated by interpolating between the actually-measured output tone levels. Then, calibration data is determined that represents a correspondence relationship between all the 0-235 original tone levels, which can be supplied from an upper rank program for producing output tone levels of 0-255, and input tone levels, that should be supplied to the printer to reproduce the corresponding tones.
Afterward, in order to control the printer to actually print desired images, original tone levels supplied from the upper rank program are converted into input tone levels using the calibration data. The converted input tone levels are then supplied to this printer so that the printer can perform printing operation to produce a printed matter.
With this configuration, if output tone levels are measured from the printed matter, the tone levels will properly match the original tone levels, in the image data originally supplied from the upper rank program.
In the above-described conceivable color calibration operations, however, the tone levels of all the patches on the test chart have to be measured. It is noted that the total number of patches is equal to the product of the total number of ink colors and the total number of patches in each color. Because there are four rows of patches with nine patches in each row in the test chart of
FIG. 1
, then the tone levels of 36 patches have to be measured. This requires a considerable amount of time. It is therefore desirable to reduce the amount of time required for measuring tone levels of the patches.
Additionally, because color calibration operations take a considerable amount of time to complete, a user will possibly desire to start printing in the middle of color calibration preparing operations. However, until the tone levels of all the printed patches are measured, calibration data can not be prepared, so the user can not start printing.
In view of the above-described drawbacks, it is an objective of the present invention to overcome the above-described problems and to provide an improved tone characteristic data producing device that is capable of preparing tone characteristic data in a short period of time and that in capable of preparing tone characteristic data even if operations for measuring tone levels of patches on the test chart are stopped short part of the way through.
In order to attain the above and other objects, the present invention provides a tone characteristic data producing device for producing tone characteristic data of an image formation device, the tone characteristic data producing device, comprising an input unit that inputs data of a plurality of input levels to an image formation device, thereby controlling the image formation device to produce a plurality of tone patches; a measurement control unit that controls a tone measurement device to measure tone of at least two tone patches among the plurality of tone patches, thereby producing data of at least two output levels indicative of the measured tone of the at least two tone patches; a characteristic data production unit that produces tone characteristic data based on relationship between the at least two output levels and corresponding input levels; and a patch number control unit that controls the number of tone patches to be measured by the tone measurement device.
The input unit may preferably input a predetermined number of input levels, for each of a plurality of colors, to the image formation device, thereby controlling the image formation device to form the predetermined number of tone patches for each color, and may further input a single lowest input level for all the colors to the image formation device, thereby controlling the image formation device to form a single tone patch common to all the colors. The patch number control unit may control the measurement control unit to cause the measurement device to measure, for each color, the predetermined number of tone patches that correspond to the predetermined number of tone patches, thereby producing the predetermined number of output levels, and to measure the single one tone patch that commonly corresponds to the lowest input levels for all the colors, thereby producing a single common output level. In this case, the characteristic data production unit produces, for each color, tone characteristic data based on the predetermined number of input levels and the predetermined number of corresponding output levels and based on the lowest input levels and the single common output level.
Thus, is this case, the image formation devise, can form images using several coloring material. The coloring material is for providing color tone. Representative examples of the coloring material are ink, toner, and the like. Because an output level corresponding to the lowest input level can be measured by only a single measurement operation. Thus, the number of patches required to be measured is decreased, and thus, the total amounts of time required for the entire measurement operation can be reduced.
The tone characteristic data producing device may further include a memory storing a standard tone characteristic data. In this case, the measurement control unit includes a judgment unit that judges, for each tone patch, whether a shift, defined between the measured output level and a corresponding standard output level that is obtained based on the standard tone characteristic data, is within a predetermined range.
For example, the characteristic data production unit may store, in the memory, the tone characteristic data produced in each characteristic data producing operation. In this case, the measurement control unit retrieves, for a present characteristic data producing operation, a set of tone characteristic data that has been produced by the tone characteristic data production unit is the latest characteristics data producing operation as the standard tone characteristic data. O

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