JP2004106523A5

JP2004106523A5 -

Info

Publication number: JP2004106523A5
Application number: JP2003288582A
Authority: JP
Filing date: 2003-08-07
Publication date: 2005-09-22
Anticipated expiration: 2023-08-07

Claims

Setting a target color mixture halftone density for each ink supply unit width when the printed pattern is divided by the ink supply unit width of the ink supply device; and
Using an IRGB densitometer to measure the actual color mixture halftone density for each ink supply unit width of the main printed sheet obtained by printing;
And a step of adjusting an ink supply amount for each ink supply unit width so that the actual mixed color halftone density approaches the target mixed color halftone density .

Between the step of measuring the actual mixed color halftone density and the step of adjusting the ink supply amount,
Obtaining a target halftone dot area ratio of each ink color corresponding to the target mixed color halftone density based on a correspondence relationship between a predetermined halftone dot area ratio and the mixed color halftone density;
Based on the correspondence between the halftone dot area ratio and the mixed color halftone density, obtaining a real halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density;
Obtaining a target monochromatic halftone density corresponding to the target halftone dot area ratio based on a correspondence relationship between a predetermined halftone dot area ratio and a monochromatic halftone density;
A step of obtaining an actual monochrome dot density corresponding to the actual dot area ratio based on the correspondence between the dot area ratio and the monochrome dot density;
Based on the correspondence relationship between the halftone dot area ratio, the monochrome halftone density, and the solid density set in advance, the solid corresponding to the deviation between the target monochrome halftone density and the actual monochrome halftone density under the target halftone dot area ratio. Obtaining a concentration deviation ,
In the step of adjusting the ink supply amount, the actual mixed color halftone density is brought close to the target mixed color halftone density by adjusting the ink supply amount for each ink supply unit width based on the solid density deviation. The pattern color tone control method for a printing press according to claim 1, wherein:

In the step of setting the target mixed color halftone density, based on the correspondence relationship between the halftone dot area ratio and the mixed color halftone density, it corresponds to the image line ratio for each ink supply unit width of each ink color in the current print pattern. 3. The picture color tone control method for a printing press according to claim 2 , wherein a mixed color halftone density is obtained and a mixed color halftone density corresponding to the image ratio is set as the target mixed color halftone density.

When an OK sheet that satisfies the print quality is obtained,
In the step of setting the target mixed color halftone density, a target pixel corresponding to each ink color is selected for each ink supply unit width from the pixels constituting the pattern of the OK sheet, and the mixed color network of the target pixel is selected. Set the density as the target mixed color halftone density,
4. The pattern color tone control method for a printing press according to claim 2 , wherein in the step of measuring the actual mixed color halftone density, the actual mixed color halftone density of the target pixel is measured.

The step of setting the target mixed color halftone density includes
Obtaining kcmy halftone dot area ratio data of the print target pattern from outside;
Selecting each pixel of interest corresponding to each ink color for each of the ink supply unit widths from the pixels constituting the print target picture;
Converting the halftone dot area ratio of the pixel of interest into a mixed color halftone density based on a correspondence relationship between a predetermined halftone dot area ratio and the mixed color halftone density, and
In the step of setting the target color mixture halftone density, the color mixture halftone density of the target pixel is set as the target color mixture halftone density,
3. The picture color tone control method for a printing press according to claim 2 , wherein in the step of measuring the actual mixed color halftone density, the actual mixed color halftone density of the target pixel is measured.

The step of setting the target mixed color halftone density includes
Obtaining kcmy halftone dot area ratio data and ICC profile of the pattern to be printed from the outside;
Selecting each pixel of interest corresponding to each ink color for each ink supply unit width from the pixels constituting the print target picture;
Converting the halftone dot area ratio of the pixel of interest into a mixed color halftone density using the ICC profile and the device profile of the IRGB densitometer,
In the step of setting the target color mixture halftone density, the color mixture halftone density of the target pixel is set as the target color mixture halftone density,
3. The picture color tone control method for a printing press according to claim 2 , wherein in the step of measuring the actual mixed color halftone density, the actual mixed color halftone density of the target pixel is measured.

The device profile is a conversion table that defines the correspondence between the dot area ratio, the mixed color halftone density, and the color coordinate value.
The step of converting the halftone dot area ratio of the target pixel into a mixed color halftone density is as follows:
Converting the dot area ratio of the pixel of interest into a color coordinate value using the ICC profile;
Obtaining a plurality of color mixture halftone density candidates corresponding to the color coordinate values of the target pixel using the conversion table;
Converting the dot area ratio of the pixel of interest into a color coordinate value using the conversion table;
Obtaining a color difference between the two color coordinate values obtained by the conversion by the ICC profile and the conversion by the conversion table;
Calculating the amount of change in the halftone dot area ratio corresponding to the color difference;
Obtaining a virtual dot area ratio obtained by adding the amount of change to the dot area ratio of the pixel of interest;
Selecting the one corresponding to the virtual halftone dot area ratio among the plurality of mixed color halftone density candidates with reference to the conversion table,
7. The image of a printing press according to claim 6 , wherein in the step of converting the halftone dot area ratio of the target pixel into a mixed color halftone density, the selected mixed color halftone density candidate is set as the mixed color halftone density of the target pixel. Color tone control method.

In the step of acquiring the kcmy halftone dot area ratio data, the bitmap data of the pattern to be printed is first acquired, and the bitmap data converted into low resolution data equivalent to CIP3 / PPF data is converted into the kcmy halftone dot. The pattern color tone control method for a printing press according to any one of claims 5 to 7, wherein the pattern color tone control method is used as area ratio data.

Obtaining a real color coordinate value corresponding to an actual color mixture halftone density of the pixel of interest measured by the IRGB densitometer based on a correspondence relationship between a preset color mixture halftone density and a color coordinate value;
Obtaining a target color coordinate value corresponding to the target color mixture halftone density based on the correspondence relationship between the color mixture halftone density and the color coordinate value;
A stop for obtaining a color difference between the actual color coordinate value and the target color coordinate value;
The picture color tone control method for a printing press according to any one of claims 4 to 8 , further comprising the step of displaying the actual color coordinate value and / or the color difference on a display device.

10. The printing machine according to claim 4 , wherein a pixel having the largest autocorrelation with respect to a dot area ratio of each pixel is automatically extracted as the target pixel for each ink color. Pattern color tone control method.

As the pixel of interest, a pixel group consisting of a pixel having the largest autocorrelation with respect to the dot area ratio of each pixel for each ink color and a plurality of surrounding pixels are automatically extracted.
In the step of setting the target color mixture halftone density, an average color mixture halftone density of the pixel group is set as the target color mixture halftone density,
The pattern color tone control method for a printing press according to any one of claims 4 to 10, wherein in the step of measuring the actual mixed color halftone density, an actual average mixed color halftone density of the pixel group is measured.

After the step of setting the target color mixture halftone density, the operation from the step of measuring the actual color mixture halftone density to the step of adjusting the ink supply amount is repeatedly executed for a predetermined period.
The picture color tone control method for a printing press according to claim 1, wherein:

An ink supply device for supplying ink to each area divided in the printing width direction;
Target color mixing halftone density setting means for setting a target color mixing halftone density for each ink supply unit width when the print pattern is divided by the ink supply unit width of the ink supply device;
An IRGB densitometer arranged on a running line of a main printing sheet obtained by printing;
A mixed color halftone density measuring means for operating the IRGB densitometer to measure an actual mixed color halftone density for each ink supply unit width of the main printing sheet;
An ink supply amount adjusting means for adjusting an ink supply amount for each ink supply unit width so that the actual mixed color halftone density approaches the target mixed color halftone density . Picture color control device.

Based on the corresponding relationship between the halftone dot area ratios and color mixture halftone densities set Me pre, target seeking target tone value of each ink color corresponding to the target color mixture halftone density is set by the target color mixture halftone density setting means Halftone dot area ratio calculating means;
Based on the correspondence between the halftone dot area ratio and the mixed color halftone density, the actual halftone dot area for obtaining the actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density measured by the mixed color halftone density measuring means. Rate calculating means;
A target monochromatic halftone density calculating means for obtaining a target monochromatic halftone density corresponding to the target halftone dot area ratio based on a correspondence relationship between a predetermined halftone dot area ratio and a monochromatic halftone density;
Based on the correspondence between the halftone dot area ratio and the monochromatic halftone density, an actual monochromatic halftone density calculating means for obtaining an actual monochromatic halftone density corresponding to the actual halftone dot area ratio;
Based on the correspondence relationship between the halftone dot area ratio, the monochrome halftone density, and the solid density set in advance, the solid corresponding to the deviation between the target monochrome halftone density and the actual monochrome halftone density under the target halftone dot area ratio. Solid density deviation calculating means for obtaining density deviation ,
The ink supply amount adjusting means adjusts the ink supply amount for each ink supply unit width based on the solid density deviation, thereby bringing the actual mixed color halftone density closer to the target mixed color halftone density. The pattern color tone control device for a printing press according to claim 13 .

A conversion table that defines the correspondence between the dot area ratio, the mixed color halftone density, and the color coordinate value in the IRGB densitometer;
The target halftone dot area ratio calculating means and the real halftone dot area ratio calculating means are configured to obtain the target halftone dot area ratio or the real halftone dot area ratio using the conversion table. The picture color tone control apparatus for a printing press according to claim 14 .

The target mixed color halftone density setting means includes:
Receiving means for receiving kcmy halftone dot area ratio data of a print target pattern from outside;
Pixel-of-interest setting means for setting each pixel of interest corresponding to each ink color for each of the ink supply unit widths from among the pixels constituting the pattern to be printed;
Conversion means for converting the halftone dot area ratio of the target pixel into a mixed color halftone density using the conversion table, and configured to set the mixed color halftone density of the target pixel as the target mixed color halftone density,
16. The picture color tone control device for a printing press according to claim 15 , wherein the mixed color halftone density measuring unit is configured to measure an actual mixed color halftone density of the target pixel.

The target mixed color halftone density setting means includes:
Receiving means for receiving the kcmy halftone dot area ratio data and ICC profile of the pattern to be printed from outside;
Pixel-of-interest setting means for setting each pixel of interest corresponding to each ink color for each of the ink supply unit widths from among the pixels constituting the pattern to be printed;
Conversion means for converting the halftone dot area ratio of the target pixel into a mixed color halftone density using the ICC profile and the conversion table, so that the mixed color halftone density of the target pixel is set as the target mixed color halftone density. Configured,
16. The picture color tone control device for a printing press according to claim 15 , wherein the mixed color halftone density measuring unit is configured to measure an actual mixed color halftone density of the target pixel.

An actual color coordinate value calculating means for obtaining an actual color coordinate value corresponding to the actual mixed color halftone density using the conversion table;
A target color coordinate value calculating means for obtaining a target color coordinate value corresponding to the target color mixture halftone density using the conversion table;
Color difference calculating means for obtaining a color difference between the actual color coordinate value and the target color coordinate value;
The picture color tone control device for a printing press according to any one of claims 15 to 17 , further comprising display means for displaying the actual color coordinate value and / or the color difference on a display device.