Color Lookup Table NPac Vector Modification for Print Grain Reduction
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Solution Overview
Problem
Existing printing systems face challenges in achieving satisfactory image quality due to colorimetric variations and contrast issues between Neugebauer Primary area coverage (NPac) vectors, leading to unsatisfactory print output.
Innovation Solution
Modifying NPac vectors in the color lookup table based on intrinsic characteristics of each NPac vector to reduce colorimetric differences between Neugebauer Primaries, thereby adjusting the statistical distribution of colorant combinations over halftones and minimizing contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NPac vectors are used in the color lookup table for printing, then color reproduction capability is improved, but colorimetric variations and contrast issues between NPac vectors cause unsatisfactory image quality
Solution Approach 1:
The patent modifies the NPac vectors by adjusting their statistical parameters to reduce colorimetric variations. Specifically, it transforms the original NPac vectors into modified NPac vectors with optimized parameters that minimize contrast differences between adjacent color regions, thereby resolving the contradiction between color reproduction capability and image quality
Solution Approach 2:
The patent implements an iterative optimization process where the colorimetric properties of printed output are measured and fed back to adjust the NPac vectors. This feedback loop continues until the colorimetric variations are minimized, achieving both accurate color reproduction and satisfactory image quality
2Adaptability or versatility
If standard NPac vectors are used for color calibration, then color space mapping is achieved, but contrast issues and graininess in print output occur
Solution Approach 1:
The patent modifies the statistical distribution parameters of NPac vectors to reduce contrast between adjacent color regions. By adjusting these parameters, the system maintains versatile color space mapping while minimizing the graininess and contrast issues that degrade print output quality
Solution Approach 2:
The patent applies different modifications to different NPac vectors based on their specific characteristics and locations in the color space. Each NPac vector is locally optimized to reduce its contribution to graininess and contrast issues, while maintaining overall color space coverage and adaptability
Data Source
AI summary
Certain examples described herein relate to adjusting a printing system. In certain cases, a lookup table, LUT, is obtained where the lookup table comprises a plurality of nodes that map a plurality of input first color space values to a plurality of Neugebauer Primary area coverage, NPac, vectors in a second color space and each NPac vector comprises at least one Neugebauer Primary, NP. Each NPac vector in the LUT is adjusted by the determination of a colorimetric value of the NPac vector and the modification of the NPac vector based on a characteristic of the corresponding at least one NP and the colorimetric value such that the modification is specific to the NPac vector. The lookup table is updated with the modified NPac vector and stored for referral by the printing system in any future printing.