Dithering based color conversion

Patent metadata

Field	Value
Publication number	US-11288558-B2
Application number	US-201817059285-A
Country	US
Kind code	B2
Filing date	Oct 31, 2018
Priority date	Oct 31, 2018
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

In some examples, dithering based color conversion may include ascertaining an input color value. Based on conversion of the input color value to an output color space representation, a set of nodes that are to be analyzed to control operation of a printer may be determined. Based on a position of the input color value from each node of the set of nodes, a corresponding probability associated with each node of the set of nodes may be determined. Further, the operation of the printer may be controlled based on the determined probability associated with each node of the set of nodes.

First claim

What is claimed is:

1. An apparatus comprising:
a processor; and
a non-transitory computer readable medium storing machine readable instructions that when executed by the processor cause the processor to:
ascertain an input color value;
determine, based on conversion of the input color value to an output color space representation, a set of nodes that are to be analyzed to control operation of a printer;
determine, based on a position of the input color value from each node of the set of nodes, a corresponding probability associated with each node of the set of nodes; and
control, based on the determined probability associated with each node of the set of nodes, the operation of the printer.

2. The apparatus according to claim 1 , wherein the instructions to determine, based on conversion of the input color value to the output color space representation, the set of nodes that are to be analyzed to control operation of the printer, are further to cause the processor to:
analyze a three-dimensional lookup table indexed with red (R), green (G), and blue (B) axes; and
determine, based on analysis of the three-dimensional lookup table to convert the input color value to the output color space representation, the set of nodes that are to be analyzed to control operation of the printer.

3. The apparatus according to claim 1 , wherein the instructions to determine, based on conversion of the input color value to the output color space representation, the set of nodes that are to be analyzed to control operation of the printer, are further to cause the processor to:
analyze a multi-dimensional lookup table indexed with a number of color values and temperature; and
determine, based on analysis of the multi-dimensional lookup table to convert the input color value to the output color space representation, the set of nodes that are to be analyzed to control operation of the printer.

4. The apparatus according to claim 1 , wherein the instructions to determine, based on conversion of the input color value to the output color space representation, the set of nodes that are to be analyzed to control operation of the printer, are further to cause the processor to:
determine, based on conversion of the input color value to the output color space representation, the set of nodes of a four-node tetrahedron.

5. The apparatus according to claim 1 , wherein the instructions to determine, based on conversion of the input color value to the output color space representation, the set of nodes that are to be analyzed to control operation of the printer, are further to cause the processor to:
determine, based on conversion of the input color value to the output color space representation, the set of nodes of an eight-node cube.

6. The apparatus according to claim 1 , wherein the instructions to control, based on the determined probability associated with each node of the set of nodes, the operation of the printer, are further to cause the processor to:
control, based on the determined probability associated with each node of the set of nodes, the operation of the printer that includes a thermal printhead.

7. The apparatus according to claim 1 , wherein the instructions to control, based on the determined probability associated with each node of the set of nodes, the operation of the printer, are further to cause the processor to:
divide, based on the determined probability associated with each node of the set of nodes, a threshold range of a dither matrix into probability ranges for printing contents of nodes of a lookup table;
determine a pixel position corresponding to the input color value;
determine, based on analysis of the set of nodes, a node of the set of nodes that corresponds to the determined pixel position and a divided threshold range of the dither matrix; and
control, based on an output pulse pattern associated with the determined node, the operation of the printer.

8. A computer implemented method comprising:
ascertaining an input color value;
converting the input color value to an output color space representation based on analysis of a multi-dimensional lookup table;
determining, based on the converting of the input color value to the output color space representation, a set of nodes from the multi-dimensional lookup table that are to be analyzed to control operation of a printhead;
determining, based on a position of the input color value from each node of the set of nodes, a corresponding probability associated with each node of the set of nodes; and
controlling, based on the determined probability associated with each node of the set of nodes, the operation of the printhead.

9. The computer implemented method according to claim 8 , wherein determining, based on the converting of the input color value to the output color space representation, the set of nodes from the multi-dimensional lookup table that are to be analyzed to control operation of the printhead, further comprises:
analyzing the multi-dimensional lookup table that includes a three-dimensional lookup table indexed with red (R), green (G), and blue (B) axes; and
determining, based on the analyzing of the three-dimensional lookup table to convert the input color value to the output color space representation, the set of nodes from the three-dimensional lookup table that are to be analyzed to control operation of the printhead.

10. The computer implemented method according to claim 8 , wherein determining, based on the converting of the input color value to the output color space representation, the set of nodes from the multi-dimensional lookup table that are to be analyzed to control operation of the printhead, further comprises:
analyzing the multi-dimensional lookup table that includes a four-dimensional lookup table indexed with cyan (C), magenta (M), yellow (Y), and black (B) axes; and
determining, based on the analyzing of the four-dimensional lookup table to convert the input color value to the output color space representation, the set of nodes from the four-dimensional lookup table that are to be analyzed to control operation of the printhead.

11. The computer implemented method according to claim 8 , wherein determining, based on the converting of the input color value to the output color space representation, the set of nodes of the multi-dimensional lookup table that are to be analyzed to control operation of the printhead, further comprises:
determining, based on the converting of the input color value to the output color space representation, the set of nodes of a four-node tetrahedron.

12. The computer implemented method according to claim 8 , wherein determining, based on the converting of the input color value to the output color space representation, the set of nodes of the multi-dimensional lookup table that are to be analyzed to control operation of the printhead, further comprises:
determine, based on the converting of the input color value to the output color space representation, the set of nodes of an eight-node cube.

13. A non-transitory computer readable medium having stored thereon machine readable instructions, the machine readable instructions, when executed, cause a processor to:
determine, based on conversion of an input color value to an output color space representation, a set of nodes that are to be analyzed to control an operation of a thermal printhead;
determine, based on a position of the input color value from each node of the set of nodes, a corresponding probability associated with each node of the set of nodes; and
control, based on the determined probability associated with each node of the set of nodes, the operation of

Assignees

• Hewlett Packard Development Co

Inventors

• Gondek Jay S
• Quintana Jason M
• Sun Weiyun

Classifications

• H04N1/52

  Circuits or arrangements for halftone screening · CPC title

• B41J2/21

  for multi-colour printing · CPC title

• G06K15/1878 Primary

  Adjusting colours (image colour correction or control for documents in general H04N1/60) · CPC title

• G06K15/1881

  Halftoning (halftoning of still images in general H04N1/405, H04N1/52) · CPC title

• B41J2/36 Primary

  Print density control · CPC title