Selective Multi-Color Calibration for Tone Continuity
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Solution Overview
Problem
Existing color image processing systems face challenges in maintaining tone continuity due to nonlinear variations in multi-color calibration, leading to potential loss of color reproduction characteristics and undesired image quality.
Innovation Solution
The system allows for selective application of multi-color calibration results during image formation, enabling control over whether to apply all correction values obtained from multi-color calibration to prevent tone continuity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-color calibration is executed to correct nonlinear variations in color values, then color accuracy is improved, but tone continuity is lost
Solution Approach 1:
The patent divides the calibration process into two separate segments: single-color calibration (correcting C, M, Y, K individually) and multi-color calibration (correcting color combinations). By segmenting the correction process, the system can apply multi-color calibration selectively without forcing it on all images, thus preventing tone continuity loss in images where it would be harmful while still achieving color accuracy where needed.
Solution Approach 2:
The patent introduces dynamic control over the calibration process by detecting whether an image contains gradation (smooth transitions) or not. Based on this detection, the system dynamically adjusts whether to apply multi-color calibration. This dynamic approach allows the system to adapt the calibration strategy to the specific image characteristics, avoiding tone continuity loss in gradation images while maintaining color accuracy in non-gradation images.
2Measurement precision
If correction values from multi-color calibration are applied to minimize color differences in Lab space, then colorimetric accuracy is improved, but mixing ratio continuity between grid points is lost
Solution Approach 1:
The patent applies partial correction by selectively using multi-color calibration results only for images that do not contain gradation. For gradation images, the system uses only single-color calibration results, avoiding the excessive correction that would disrupt mixing ratio continuity. This partial application of correction achieves colorimetric accuracy where appropriate without causing the harmful side effects in cases where it would be excessive.
3Measurement precision
If all correction values from multi-color calibration are applied during image formation, then overall color reproduction is improved, but continuity of tone in smooth images is lost
Solution Approach 1:
The patent incorporates a feedback mechanism where the system first detects whether an image contains gradation before deciding how to apply calibration corrections. This feedback loop allows the system to adjust its correction strategy based on the actual image content, ensuring that multi-color calibration is applied only when it will improve overall color reproduction without harming tone continuity in smooth gradation areas.
Data Source
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AI summary
In a color image processing apparatus in the present invention, correction values used for causing reproduction characteristics of multi-colors formed by an image forming unit (115) to be close to target values are obtained using results of measurement of colors of multi-color patch images formed by the image forming unit using a plurality of recording materials. The color image processing apparatus includes a first processing unit (114) configured to, when the image forming unit forms a color image, execute a correction process using the correction values, a second processing unit (114) configured to, when the image forming unit forms the color image, execute the correction process without using at least some of the correction values or not to execute the correction process, and a control unit (114) configured to selectively cause the first processing unit and the second processing unit to operate.