Color separation based on maximum toner limits

• US 7,433,100 B2
• Filed: 05/30/2003
• Issued: 10/07/2008
• Est. Priority Date: 05/30/2003
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Jacob, Steve A.
• Primary Examiner(s): Nguyen; Madeleine A
• Application Number:
  US10/448,596
• Publication Number:
  US 20050030559A1
• Time in Patent Office: 1,957 Days
• Field of Search: 358/1.9, 358/515, 358/539, 358/525, 358/523, 358/540, 358/518, 358/529, 358/501, 358/504, 382/167, 382/162
• US Class Current: 358/518
• CPC Class Codes: G06K 15/129 Colour printing
• CPC Class Codes: H04N 1/6022 Generating a fourth subtractive colour signal, e.g. under colour removal, black masking

Abstract

Various systems, methods, and programs embodied in a computer readable medium for determining color separation are provided. In one representative embodiment, a method is provided that comprises specifying a number of nodes along a number of ramps in a predefined color conversion space in a computer system. A maximum possible toner deposit is associated with each of these nodes. In addition, a maximum toner limit is specified for each one of the nodes along the ramps in the computer system. Each of the maximum toner limits is less than the maximum possible toner deposit. In addition, a color separation is determined for each of the nodes along the ramps in the computer system. Each of the color separations specifies up to a maximum amount of toner equaling a corresponding one of the maximum toner limits.

Claims

1. A method for determining color separation, comprising the steps of:

specifying a number of nodes along a number of ramps in a predefined color conversion space in a computer system, wherein a maximum possible toner deposit is associated with each of the nodes along the ramps;

specifying a maximum toner limit for each one of the nodes along the ramps in the computer system, wherein each of the maximum toner limits is less than the maximum possible toner deposit;

determining a color separation for each of the nodes along the ramps in the computer system; and

reducing an amount of toner associated with each respective one of the color separations by only reducing an amount of toner of an independent color component, or a set of paired color components so that each respective one of the color separations specifies up to a maximum amount of toner equaling a corresponding one of the maximum toner limits.

2. The method of claim 1, wherein the step of determining the color separation for each of the nodes along the ramps further comprises determining the color separations for each of the nodes based upon a printer color characterization.

3. The method of claim 1, further comprising the step of interpolating a color separation for each one of a number of interstitial nodes from the color separations of the nodes along the ramps in the computer system.

4. The method of claim 1, wherein the step of determining the color separation for each of the nodes along the ramps in the computer system further comprises the steps of:

calculating a number of potential color separations for each of the nodes along the ramps; and

identifying one of the potential color separations having a maximum colorfulness as the color separation for each of the nodes along the ramps.

5. The method of claim 1, wherein the step of determining the color separation for each of the nodes along the ramps further comprises the step of determining the color separation for each of the nodes along a primary ramp of a predefined color conversion space.

6. The method of claim 1, wherein the step of determining the color separation for each of the nodes along the ramps further comprises the step of determining the color separation for each of the nodes along a secondary ramp of a predefined color conversion space.

7. The method of claim 1, wherein the step of determining the color separation for each of the nodes along the ramps further comprises the step of determining the color separation for each of the nodes along a neutral ramp of a predefined color conversion space.

8. The method of claim 1, wherein the step of determining the color separation for each of the nodes along the ramps in the computer system further comprises the steps of:

determining an initial color separation for each of the nodes along the ramps; and

performing an optimization on each of the initial color separations to obtain the color separations for each of the nodes, wherein the optimization causes each of the color separations to approach a corresponding target color and the optimization results in each of the color separations specifying up to the maximum amount of toner equaling the corresponding one of the maximum toner limits.

9. The method of claim 8, wherein the step of performing the optimization on each of the initial color separations to obtain the color separations for each of the nodes further comprises the step of performing a Nelder-Mead optimization.

10. A program embodied in a computer readable medium for determining color separation, comprising:

code that defines a number of nodes specified along a number of ramps in a predefined color conversion space, wherein a maximum possible toner deposit is associated with each of the nodes along the ramps;

code that defines a maximum toner limit specified for each one of the nodes along the ramps, wherein each of the maximum toner limits is less than the maximum possible toner deposit;

code that determines a color separation for each of the nodes along the ramps; and

code that reduces an amount of toner associated with each respective one of the color separations by only reducing an amount of toner of an independent color component, or a set of paired color components so that each of the color separations specifies up to a maximum amount of toner equaling a corresponding one of the maximum toner limits.

11. The program embodied in the computer readable medium of claim 10, wherein the code that determines the color separation for each of the nodes along the ramps further comprises code that determines the color separations for each of the nodes based upon a printer color characterization.

12. The program embodied in the computer readable medium of claim 10, further comprising code that interpolates a color separation for each one of a number of interstitial nodes from the color separations of the nodes along the ramps.

13. The program embodied in the computer readable medium of claim 10, wherein the code that determines the color separation for each of the nodes along the ramps further comprises:

code that calculates a number of potential color separations for each of the nodes along the ramps; and

code that identifies one of the potential color separations having a maximum colorfulness as the color separation for each of the nodes along the ramps.

14. The program embodied in the computer readable medium of claim 10, wherein the code that determines the color separation for each of the nodes along the ramps further comprises code that determines the color separation for each of the nodes along a primary ramp of a predefined color conversion space.

15. The program embodied in the computer readable medium of claim 10, wherein the code that determines the color separation for each of the nodes along the ramps further comprises code that determines the color separation for each of the nodes along a secondary ramp of a predefined color conversion space.

16. The program embodied in the computer readable medium of claim 10, wherein the code that determines the color separation for each of the nodes along the ramps further comprises code that determines the color separation for each of the nodes along a neutral ramp of a predefined color conversion space.

17. The program embodied in the computer readable medium of claim 10, wherein the code that determines the color separation for each of the nodes along the ramps further comprises:

code that determines an initial color separation for each of the nodes along the ramps; and

code that performs an optimization on each of the initial color separations to obtain the color separations for each of the nodes, wherein the optimization causes each of the color separations to approach a corresponding target color and the optimization results in each of the color separations specifying up to the maximum amount of toner equaling the corresponding one of the maximum toner limits.

18. The program embodied in the computer readable medium of claim 17, wherein the code that performs the optimization on each of the initial color separations to obtain the color separations for each of the nodes further comprises code that performs a Nelder-Mead optimization.

19. A system for determining color separation, comprising:

means for defining a number of nodes specified along a number of ramps in a predefined color conversion space, wherein a maximum possible toner deposit is associated with each of the nodes along the ramps;

means for defining a maximum toner limit specified for each one of the nodes along the ramps, wherein each of the maximum toner limits is less than the maximum possible toner deposit;

means for determining a color separation for each of the nodes along the ramps; and

means for reducing an amount of toner associated with each respective one of the color separations by only reducing an amount of toner of an independent color component or a set of paired color components so that each of the color separations specifies up to a maximum amount of toner equaling a corresponding one of the maximum toner limits.

20. The system of claim 19, wherein the means for determining the color separation for each of the nodes along the ramps further comprises means for determining the color separations for each of the nodes based upon a printer color characterization.

21. The system of claim 19, further comprising means for interpolating a color separation for each one of a number of interstitial nodes from the color separations of the nodes along the ramps.

22. The system of claim 19, wherein the means for determining the color separation for each of the nodes along the ramps further comprises:

means for calculating a number of potential color separations for each of the nodes along the ramps; and

means for identifying one of the potential color separations having a maximum colorfulness as the color separation for each of the nodes along the ramps.

23. The system of claim 19, wherein the means for determining the color separation for each of the nodes along the ramps further comprises:

means for determining an initial color separation for each of the nodes along the ramps; and

means for performing an optimization on each of the initial color separations to obtain the color separations for each of the nodes, wherein the optimization causes each of the color separations to approach a corresponding target color and the optimization results in each of the color separations specifying up to the maximum amount of toner equaling the corresponding one of the maximum toner limits.

24. The system of claim 23, wherein the optimization further comprises a Nelder-Mead optimization.

25. A system for determining color separation, comprising:

a processor circuit having a processor and a memory;

a color separation calculation system stored in the memory and executable by the processor, the color separation calculation system comprising;

a number of nodes defined in the memory that are specified along a number of ramps in a predefined color conversion space, wherein a maximum possible toner deposit is associated with each of the nodes along the ramps;

a maximum toner limit stored in the memory that is specified for each one of the nodes along the ramps, wherein each of the maximum toner limits is less than the maximum possible toner deposit;

logic that determines a color separation for each of the nodes along the ramps; and

logic that reduces an amount of toner associated with each respective one of the color separations by only reducing an amount of toner of an independent color component. or a set of paired color components so that each of the color separations specifies up to a maximum amount of toner equaling a corresponding one of the maximum toner limits.

26. The system of claim 25, wherein the logic that determines the color separation for each of the nodes along the ramps further comprises logic that determines the color separations for each of the nodes based upon a printer color characterization.

27. The system of claim 25, further comprising logic that interpolates a color separation for each one of a number of interstitial nodes from the color separations of the nodes along the ramps.

28. The system of claim 25, wherein the ramps further comprise a primary ramp of a predefined color conversion space.

29. The system of claim 25, wherein the ramps further comprise a secondary ramp of a predefined color conversion space.

30. The system of claim 25, wherein the ramps further comprise a neutral ramp of a predefined color conversion space.