Image Processing Method for Printer Color Uniformity
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Solution Overview
Problem
Existing image processing methods for printers face challenges in suppressing color unevenness between normal and overlapping regions due to differences in recording conditions, leading to defects in ink amount adjustments and balance between lookup tables.
Innovation Solution
An image processing method that includes a first conversion step using a first conversion table to convert image data from a first color space to a second color space, and a second conversion step using a second conversion table to adjust image data for regions with different recording conditions, generating recording data that reflects necessary ink amount adjustments to minimize color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate LUTs are used for normal region and overlapping region color conversion, then color unevenness can be suppressed, but adjusting ink amount in each LUT causes loss of ratio and balance between output values
Solution Approach 1:
The patent divides the image into normal regions and overlapping regions, applying different conversion strategies to each. Normal regions use a first LUT for color conversion, while overlapping regions use a second LUT, allowing targeted optimization for each region's specific recording conditions without interference between them.
Solution Approach 2:
The patent introduces an intermediary conversion process that converts CMYK values to a temporary color space before final output. This intermediary step allows ink amount adjustment to be applied uniformly without disrupting the balance relationships established by the region-specific LUTs, acting as a buffer that preserves color relationships while enabling adjustment.
2Manufacturing precision
If different conversion tables are used for different regions, then color unevenness is suppressed, but the complexity of the conversion process increases
Solution Approach 1:
The conversion process is segmented into distinct stages: first converting image data to CMYK using region-appropriate LUTs, then converting CMYK to a temporary color space, and finally converting to output color space. This segmentation allows each stage to be optimized independently, managing overall complexity through structured decomposition.
Solution Approach 2:
The patent changes the parameter representation by introducing a temporary color space as an intermediate state. This parameter transformation allows the system to maintain multiple LUTs for different regions while using a unified adjustment mechanism in the temporary color space, reducing the operational complexity despite the multiple conversion tables.
3Manufacturing precision
If ink amount is adjusted in the second conversion step, then recording conditions for different regions can be optimized, but the balance between output values from different LUTs is lost
Solution Approach 1:
The patent performs preliminary color conversion using region-specific LUTs to establish proper color relationships before any uniform adjustments are made. By completing the region-differentiated conversion first, the system ensures that the fundamental color balance is established, and subsequent uniform adjustments in the temporary color space do not disrupt this balance.
Solution Approach 2:
The temporary color space serves as an intermediary that decouples the region-specific conversion from the uniform adjustment process. Adjustments made in this intermediary space affect all regions equally without altering the relative balance established by the separate LUTs, allowing optimization without disrupting color relationships.
Data Source
AI summary
An image processing method includes a first conversion step, a second conversion step that, using a second conversion table for converting input image data represented by a second color space to output image data represented by the second color space, converts image data of a second region for which recording conditions are different from a first region in a second image data, and a recording data generating step that generates recording data based on third image data including image data of a first region in the second image data and image data of the second region after conversion using the second conversion table. When adjusting an ink amount, the ink amount is not adjusted in the second conversion step and is adjusted in the first conversion step.