Multi-Color Density Correction Using Overlay Ratios
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image processing techniques require an enormous amount of test patterns and operations to correct density values for multi-color printing, leading to inefficiencies and increased complexity, especially when dealing with vertical streaks and density changes in image forming apparatuses.
Innovation Solution
An image processing apparatus and method that stores correction information for each color, allowing for the correction of density values using a value smaller than the corresponding correction value, eliminating the need for test patterns for every color combination by using a correction coefficient equal to or smaller than one, thereby simplifying the correction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If correction tables are created for every combination of primary colors to obtain tone characteristics, then manufacturing precision of color output is improved, but device complexity and operational burden increase enormously
Solution Approach 1:
The patent divides the correction process into two independent segments: (1) create correction tables for each primary color separately using single-color test patterns, and (2) combine these corrections using overlay ratios during multi-color printing. This segmentation eliminates the need to create correction tables for every color combination, reducing complexity while maintaining precision.
Solution Approach 2:
The patent performs preliminary correction table creation for each primary color individually before actual multi-color printing operations. By pre-calculating corrections for cyan, magenta, yellow, and black separately using simple single-color test patterns, the system avoids the need for complex multi-color test patterns and subsequent complex corrections.
2Measurement precision
If test patterns are formed for every combination of primary colors, then measurement precision of tone characteristics is improved, but productivity and operational efficiency deteriorate
Solution Approach 1:
The patent extracts the essential correction information by forming test patterns for each primary color independently, separating the correction measurement process from the complex multi-color printing process. This extraction allows obtaining necessary tone characteristics using only single-color test patterns, eliminating the need for numerous multi-color test pattern formations.
Solution Approach 2:
The patent changes the measurement approach by measuring each primary color's tone characteristic separately using single-color test patterns, then combining these measurements using overlay ratios. This parameter change from measuring color combinations to measuring individual colors dramatically reduces the number of required test patterns while maintaining measurement accuracy.
3Ease of operation
If correction values are applied without considering color overlay ratios, then ease of operation is improved, but manufacturing precision of multi-color output deteriorates
Solution Approach 1:
The patent introduces dynamic adjustment of correction values based on color overlay ratios. The correction applied to each primary color is dynamically modified according to the presence and density of other colors in the same pixel, using the formula: corrected_value = original_correction × (1 - overlay_ratio). This dynamic adjustment maintains simplicity while achieving high precision.
Solution Approach 2:
The patent applies different correction strategies to different spatial locations and color combinations. For pixels containing only a single color, full correction is applied; for pixels with multiple colors, the correction is locally adjusted based on the specific overlay ratio of that pixel, ensuring precision without requiring separate correction tables for every possible color combination.
Data Source
AI summary
An image processing apparatus includes: a storage unit to store therein, for each of a plurality of colors, correction information in which a correction value for obtaining a target output value is associated with each of combinations of one of a plurality of density values of image data corresponding to the color and one of a plurality of positions in a main scanning direction of image data; and a corrector to correct, when a pixel in input image data indicating image data received from a host device includes two or more colors, for each of the two or more colors, a density value of the color using a value smaller than a correction value corresponding to a combination of the density value of the color and a position of the pixel in the main scanning direction.