Prediction of graininess and production of profile

Abstract

A color patch that was printed based on a plurality of test ink quantity sets prepared in advance is image inputted; a graininess index is calculated based on the inputted color patch image; the graininess index on a printing medium obtained when printing is performed according to an arbitrary ink quantity set is predicted based on a graininess profile produced based on the corresponding relationship between the test ink quantity set and the graininess index.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating by way of an example a configuration of a graininess prediction apparatus;

FIG. 2 is a flowchart illustrating by way of an example a processing procedure relating to prediction of graininess;

FIG. 3 is an explanatory drawing illustrating by way of an example the state of GI computation;

FIG. 4 is a flowchart illustrating by way of an example the flow of graininess profile production processing;

FIG. 5 illustrates by way of an example a neural network structure;

FIG. 6 is a graph illustrating by way of an example the state of fitting with a NN;

FIG. 7 is a block diagram illustrating by way of an example a configuration example of a profile production apparatus;

FIG. 8 is a flowchart illustrating by way of an example the processing procedure of profile production;

FIG. 9 is a graph illustrating by way of an example a sample color within a CIELAB space in the present embodiment;

FIG. 10 is a flowchart illustrating by way of an example the detailed procedure of step S35;

FIG. 11 illustrates by way of an example the gamut mapping in step S50;

FIG. 12 illustrates by way of an example the Spectral Neugebauer Model;

FIG. 13 illustrates by way of an example the Cellular Yule-Nielsen Spectral Neugebauer Model;

FIG. 14 illustrates grid point coordinates of cell division in the Cellular Yule-Nielsen Spectral Neugebauer Model;

FIG. 15 illustrates a method for finding a spectral reflectance that cannot be measured in the Cellular Yule-Nielsen Spectral Neugebauer Model; and

FIG. 16 illustrates an example of LUT.

Claims

1. A method for predicting a graininess on a printing medium when printing is performed according to an ink quantity set of inks that can be used in a printer, the method comprising: (a) image inputting a color patch that has been printed based on a plurality of test ink quantity sets prepared in advance;(b) calculating a graininess index based on an inputted color patch image; and(c) predicting the graininess index on the printing medium when printing is performed according to any ink quantity set based on a graininess profile produced based on a corresponding relationship between the test ink quantity set and the graininess index.

2. The method according to claim 1, wherein the graininess profile is a neural network in which each parameter is optimized based on the corresponding relationship between the test ink quantity set and the graininess index.

3. The method according to claim 2, wherein each parameter of the neural network is optimized so as to reduce an error between the graininess index obtained by inputting the test ink quantity set into the neural network and the graininess index obtained by evaluating the color patch.

4. The method according to claim 3, wherein each parameter of the neural network is optimized so as not to over-reduce the error between the graininess index obtained by inputting the test ink quantity set into the neural network and the graininess index obtained by evaluating the color patch.

5. The method according to claim 4, wherein the graininess profile is a lookup table recording the corresponding relationship between the test ink quantity set and the graininess index.

6. An apparatus for predicting a graininess on a printing medium when printing is performed according to an ink quantity set of inks that can be used in a printer, the apparatus comprising: an input unit that image inputs a color patch that has been printed based on a plurality of test ink quantity sets prepared in advance;a production unit that calculates a graininess index based on the inputted image and produces a graininess profile based on a corresponding relationship between the ink quantity set and the graininess index; anda prediction unit that predicts the graininess index on the printing medium when printing is performed according to any ink quantity set based on the graininess profile.

7. A method for producing a profile that stipulates a corresponding relationship between ink quantity data that represent ink quantity sets of a plurality of inks that can be used in a printer and a color measurement value obtained when printing is performed in the printer according to the ink quantity data, the method comprising the steps of:(a) image inputting a color patch that has been printed based on a plurality of test ink quantity sets prepared in advance;(b) calculating a graininess index based on an inputted color patch image;(c) predicting the graininess index on the printing medium when printing is performed according to an arbitrary ink quantity set based on a graininess profile produced based on a corresponding relationship between the test ink quantity set and the graininess index; and(d) producing the profile based on a corresponding relationship between the ink quantity set for which at least the graininess index predicted is favorable and a color measurement value obtained when printing is performed with the ink quantity set.