Method of modifying a data set containing color component values

Abstract

The invention relates to a method of modifying a data set containing color component values, which method allows the component of a color in a color spectrum that is provided to be generally set to zero and thus not to use that color. For this purpose, it is provided to first select an image area of a printed product, i.e. a portion of the data set. Further, it is determined which color from the color spectrum shall not be used. The color value for the selected image area is determined. A tolerance range around the color value is fixed. In a further step, it is determined which combinations of color component values that are formed of the remaining colors of the color spectrum include color values that are within the tolerance range fixed around the color value of the selected area. Thereafter, one of the combinations of the color component values is selected. Finally, the color component values are exchanged for the color component values from the selected combination of color component values in the selected portion of the data set.

Claims

1. Method for modification of the color component values for a number of individual colors defining a color spectrum which are used in a data set for the production of a printed product on a target printing machine, wherein: a) a portion of the data set is selected which corresponds to a fixed image area of the printed product; b) the colorimetrically determinable color values are determined for the selected area; c) a tolerance range around the determined color values is fixed; d) one or several individual colors that shall not be used are determined, whereby the color component values thereof are set to zero; e) combinations of color component values are determined from the remaining individual colors whose color values are within said tolerance range and thus reproduce the original color spectrum as well as possible; f) the determined combinations of color component values are selected; g) the color component values in the selected area are exchanged for the selected color component combinations.

2. Method according to claim 1, wherein said color component values are set in the CMYK color space.

3. Method according claim 1, wherein said color component values are set in the L*a*b* color space.

4. Method according to claim 1, wherein in step f) combinations of color component values are excluded which contain color component values within a predetermined tolerance spectrum.

5. Method according to claim 4, wherein said tolerance spectrum is set in the range between 0% and an upper limit that is prescribed by industrial reproducibility.

6. Method according to claim 1, wherein said tolerance spectrum is formed by distance values lying in one color space.

7. Method according to claim 1, wherein in method step f) those combinations of color components are excluded which exceed a predetermined total area coverage value.

8. Method according to claim 1, wherein the selection of the portion of the data set according to method step a) takes place graphically using a digital presentation of the printed product.

Description

(1) The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

(2) Further advantages and features will become apparent from the following description with reference to the attached drawing figures wherein it is shown by:

(3) FIG. 1 the representation of a printed product;

(4) FIG. 1a, b, c, d representations symbolizing color component values of the individual colors CMYK;

(5) FIG. 2 the representation of a printed product according to FIG. 1 with a selected area;

(6) FIG. 3 the representation of a printed product according to FIG. 1 after modification of the data set; and

(7) FIG. 3a, b, c, d representations symbolizing the color component values of the individual colors CMYK.

(8) FIG. 1 shows as an exemplary printed product the representation of a tomato. This printed product has been produced based on an original data set including color component values for the colors CMYK. These are the colors cyan, magenta, yellow, and black. As shown by the FIGS. 1a, b, c, d, the image contains different percentages of the respective color at the individual pixels, which fact is symbolized in the individual images.

(9) According to FIG. 2, a specific area of the visual representation shall be produced without using the color cyan.

(10) In accordance with the method, the L*a*b* value is now determined for each image pixel in the area, which is not illustrated in the Figures. Then combinations of color component values are searched in which the share corresponds to C=0% and in which the L*a*b* value of the combination of the remaining three colors is however comparable to the original L*a*b* value or is very close to it. After the selection of a corresponding combination, the color component values in the data set are exchanged.

(11) FIG. 3 now shows the printed product after modification of the data set, wherein the correspondingly modified components of the remaining colors can now be seen in the FIGS. 3a, b, c, d, while the color cyan is no longer present in the area. You see a higher share of the color black and also a corresponding share of the color magenta.

(12) For example, if originally in the CMYK color component value combination C=30, M=50, Y=60, and K=20, a combination may be used with C=0, M=45, Y=60, and K=55 after the modification.

(13) The described embodiment merely serves the purpose of explanation and is not in any way limiting.