Color Transform Purifying Primary Colors in CMYK Conversion

Solution Overview

Problem

In color managed CMYK to CMYK conversions, pure primary color values are often 'muddied' by small amounts of impurities during the conversion process, leading to undesirable artifacts such as registration errors and halftone dots, especially in narrow lines or edges, as conventional methods fail to preserve color purity.

Innovation Solution

A color correction transform is determined to remove impurities from muddied primary color values, purifying them and smoothly transitioning between purified and uncorrected non-primary color values, which can be incorporated into device-type profiles or Color Management Modules (CMMs, allowing for accurate color representation while maintaining relative color correspondence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If color values are converted from input CMYK color space to output CMYK color space using conventional color management, then relative color correspondence is maintained, but primary color purity is lost due to muddying

Engineering Contradiction:

Improverelative color correspondenceVSAvoidprimary color purity

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent applies local quality by treating primary color values differently from non-primary color values during conversion. Specifically, primary color values (C=1,M=0,Y=0), (C=0,M=1,Y=0), and (C=0,M=0,Y=1) are identified and processed through a purification step that removes impurities, while other color values undergo standard conversion. This localized treatment preserves the purity of primary colors while maintaining relative correspondence for the broader color space.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by first performing the color space conversion and then applying a purification step that reverses the muddying effect on primary colors. Instead of accepting the muddied output as final, the method identifies primary color values in the output space and actively removes impurities from them, effectively undoing the conventional conversion's side effect on primary colors.

Inventive Principle:

Principle #13The other way round (Inversion)

2Manufacturing precision

If primary color values are purified to remove impurities, then color purity is improved, but discontinuities and artifacts appear in the color space

Engineering Contradiction:

Improveprimary color purityVSAvoidcolor space continuity

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent introduces an intermediary approach by applying a smoothing operation that acts as a mediator between the purified primary color values and the surrounding color values. The smoothing step adjusts nearby color values to transition smoothly toward the purified primary colors, eliminating abrupt discontinuities and artifacts while preserving the purity benefits.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies color component parameters through the smoothing operation, adjusting the C, M, and Y values of colors near the purified primary colors. This parameter adjustment creates a gradual transition zone that eliminates discontinuities while maintaining the overall purity improvement achieved by the purification step.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If color management systems maintain relative correspondence of all colors, then overall color accuracy is improved, but pure primary colors become contaminated with impurities

Engineering Contradiction:

Improveoverall color accuracyVSAvoidprimary color purity

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent applies local quality by treating primary color values differently from non-primary color values during conversion. Specifically, primary color values (C=1,M=0,Y=0), (C=0,M=1,Y=0), and (C=0,M=0,Y=1) are identified and processed through a purification step that removes impurities, while other color values undergo standard conversion. This localized treatment preserves the purity of primary colors while maintaining relative correspondence for the broader color space.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by first performing the color space conversion and then applying a purification step that reverses the muddying effect on primary colors. Instead of accepting the muddied output as final, the method identifies primary color values in the output space and actively removes impurities from them, effectively undoing the conventional conversion's side effect on primary colors.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS7911665B1Preserving pure primary colors in color transforms

Publication Date: 2011.03.22 ADOBE INC

AI summary

The subject matter disclosed herein relates to purifying muddied primary color values of an output color space and correcting a portion of non-primary color values of the output color space so as to smoothly transition from the purified primary color values to uncorrected non-primary color values.