JP2009038734A - Method to select output chart pattern for measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method to decide an efficient repetitive pattern for improving measurement accuracy, in a combination with an actual printer that executes calibration or profile preparation and a measurement machine. <P>SOLUTION: A patch chart is composed by arranging the same color in a plane vertically and horizontally, and one or a plurality of patch charts are outputted from a printer so as to measure the output color of each patch. The whole reference value is calculated from the measured value. In accordance with a plurality of in-plane repeated patterns, an evaluation value is calculated from the relation between a measured value for each total number of sheets in each pattern and the reference value as a whole. An efficient repeated pattern and the number of charts are decided from the transition of an evaluation value, in a combination of the pattern and the total number of sheets. The repeated pattern and the number of charts decided in such a manner are used and a chart for calibration or profile preparation is generated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printer output chart for measuring color reproduction characteristics of a printer, such as printer calibration or profile creation.

As a patch coloration method for reducing the influence of in-plane unevenness in a conventional output chart, a method of arranging patches of the same color so as to be perpendicular to the longitudinal direction of density unevenness (see Patent Document 1), or a patch at random There exists a method (refer patent document 2) to arrange | position.
JP 2001-094803 A USP 5760913

  In order to reduce the influence of in-plane unevenness, the same color is repeatedly output to different positions and the average of multiple measurements is taken. However, the repeated pattern is fixed in advance. Or randomly arranged. For this reason, the optimum color scheme is not always obtained in a combination of a printer and a measuring machine actually used by the user.

  It is an object of the present invention to provide an efficient method for determining a repetitive pattern for improving measurement accuracy in an actual printer / measuring machine combination for performing calibration or profiling.

  A patch chart in which the same colors are arranged vertically and horizontally in the plane is output from one or a plurality of printers, and the output color of each patch is measured. The overall reference value is obtained from the measured value. In accordance with a plurality of in-plane repeating patterns, an evaluation value is calculated from the relationship between the measured value of the cumulative number of each pattern and the overall reference value. An efficient repetitive pattern and the number of charts are determined from the transition of the evaluation value in the combination of the pattern and the cumulative number. A chart for calibration or profile creation is generated using the repetitive pattern and the number of charts thus determined.

  In the combination of the printer and the measuring machine, the color reproduction accuracy by calibration or profile creation is improved by obtaining a chart format (repeated pattern, number of sheets) that reduces the influence of variation in chart output color due to in-plane unevenness. effective.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, and FIG. 2 is a flowchart showing a procedure of the embodiment of the present invention.

  (Step 20) The chart 5 for evaluation is printed on the printer 2 from the printing unit 6 to obtain a printed chart 3. FIG. 3 shows an example of a printed chart for evaluation. A plurality of charts in which gray intermediate color patches (R128, G128, B128) are arranged vertically and horizontally are output.

  (Step 21) The chart printed matter 3 is measured by the measuring unit 7 from the measuring instrument 4, and the chart measurement value 8 is obtained. Here, the measured value is measured for every patch in FIG. The measuring device 4 is a device such as a scanner or a colorimeter, and the measured value is a scanner RGB value or a Lab value.

  (Step 22) The reference value 10 is obtained from the measured values of all the vertical and horizontal patches across the plurality of chart measured values 8. For example, an average value of all measured values (average value for each component such as RGB and Lab) is obtained as a reference value.

  (Step 23) The repetitive pattern generation unit 13 generates the repetitive pattern 12. Processing in which all types of patterns to be used in advance are stored in the storage device and taken out one by one in order may be used. The repeating pattern is obtained by dividing the vertical and horizontal patches of the chart printed matter 3 into vertical and horizontal repetitions of the same number of small groups. When fractions are output, the columns or rows corresponding to the fractions are excluded from the edge of the paper and divided. FIG. 4 shows two types of repetitive pattern examples. The left example is a 3 × 3 repetitive pattern, and the right example is a 4 × 2 repetitive pattern. When used as an actual chart, a patch color is assigned to each position of the small group, and the average value of the measured values of the same patch color is used as the measured value.

  (Step 24) If all types of patterns have been processed, the process proceeds to step 26; otherwise, the process proceeds to step 25.

  (Step 25) The evaluation unit 9 calculates a pattern evaluation value 11 for the repetitive pattern 12 currently being processed. FIG. 5 shows an example of a repetitive pattern evaluation formula. Each block is expressed as B42 [k, l] in a repetition pattern of 4 × 2 in the right side of FIG. k indicates the vertical, and l indicates the horizontal block index. Since a plurality of chart printouts 3 are output, they are distinguished from each other, and each block of the pth sheet is denoted as B42 [p] [k, l]. Further, the measured value of the patch in the block is expressed as B42 [p] [k, l] [i, j] using the index (vertical i, horizontal j) in the block. An average is taken for each same position [i, j] in each block. The color difference between the average up to the r-th sheet and the reference value 10 is obtained for each position [i, j], and the maximum value when [i, j] is changed is the r of the repeated pattern KL of vertical K × horizontal L. Assume that the evaluation value V (KL, r) in the cumulative number of sheets.

  (Step 26) After the evaluation of all patterns, the repetitive pattern and the number of sheets are determined from the relationship between the evaluation value and r and set to the selection pattern 14. FIG. 6 is an example of a graph showing the transition of the evaluation value according to the cumulative number of each repeated pattern. There are three types of repetitive patterns (61 to 63), the accumulated color difference from 1 to 5 is shown, and the lower the value, the higher the evaluation. In this example, the pattern 63 having the highest evaluation is selected, and the number of sheets is determined to be two in consideration of efficiency. This pattern and number information are set in the selection pattern 14.

  (Step 27) The chart generation unit 15 generates the patch chart 17 using the determined selection pattern 14 and information on the patch color 16 prepared in advance.

The block diagram which shows the structure of the Example of this invention. The flowchart which shows the procedure of the Example of this invention Schematic diagram showing an example of a printed chart for evaluation Schematic diagram showing two examples of repeated patterns Example of repeated pattern evaluation formula Graph example showing the transition of evaluation value based on the cumulative number of three types of repeated patterns

Explanation of symbols

1 PC
DESCRIPTION OF SYMBOLS 2 Printer 3 Chart printed matter 4 Measuring machine 5 Evaluation chart 6 Printing part 7 Measuring part 8 Chart measured value 9 Evaluation part 10 Reference value 11 Pattern evaluation value 12 Repeat pattern 13 Repeat pattern generation part 14 Selection pattern 15 Chart generation part 16 Patch color 17 Patch chart 20 to 27 Steps 61 to 63 of the flowchart Graph showing the color difference transition by the cumulative number of three types of repeated patterns

Claims (1)

  An output chart pattern selection method for measurement, characterized in that, in a printer output chart for calibration and profile creation, the repeated pattern and the number of output sheets of the chart are changed according to the combination of the printer and the measuring machine.

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