Calibration Apparatus Color Deviation Inversion Analysis
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Solution Overview
Problem
Conventional image forming apparatus calibration techniques are complex and fail to accurately determine the optimum gray balance, especially when dealing with color deviations, leading to suboptimal calibration results, particularly in visual evaluations.
Innovation Solution
A calibration apparatus that calculates and displays the number of inversions and variation width of color deviations for each gray balance, allowing users to determine the degree of color transition and apply a gray balance with a lower transition degree for improved calibration, using a color conversion processing system with a display unit to visualize these metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple feedbacks are executed to enhance gray balance accuracy, then color reproducibility improves, but the calibration process becomes complex and difficult to determine the optimum gray balance
Solution Approach 1:
The patent implements multiple feedback loops where colorimetric values are measured after each gray balance correction, and correction values are calculated based on the differences between measured and target values. This iterative feedback process continues until the gray balance converges to the target, ensuring high accuracy while providing a systematic approach to manage the complexity through automated feedback control
Solution Approach 2:
The patent introduces new evaluation parameters including the number of times the sign of color deviation is inverted and the variation width of color deviation. These parameters provide quantitative metrics to evaluate and compare different gray balance correction results, enabling objective selection of the optimum gray balance without manually analyzing complex calibration data
2Ease of operation
If conventional color difference ΔE evaluation is used, then numerical evaluation is simple, but visual evaluation accuracy deteriorates when color deviation directions are inverted
Solution Approach 1:
The patent explicitly monitors and evaluates the inversion of color deviation sign directions (e.g., when Δa* or Δb* changes from positive to negative or vice versa). By detecting and quantifying these inversions, the system identifies cases where conventional ΔE evaluation may be misleading and uses the inversion count as an additional criterion to select the most visually accurate gray balance
Solution Approach 2:
The patent extends the evaluation from a single-dimensional color difference ΔE to multi-dimensional analysis by tracking the sign inversion behavior across different color axes (a* and b*). This adds a temporal and directional dimension to the evaluation, allowing detection of color transition patterns that single-value ΔE cannot capture
Data Source
AI summary
A calibration apparatus for an image forming apparatus includes a calculation unit for calculating a color deviation by subtracting a target value from each value on the two orthogonal axes not including brightness of a color coordinate system based on a measured color value of a printed material and a display unit for displaying the color deviation with respect to each gray balance at the feedback such that the number of times of inversions of a sign of the color deviation calculated by the calculation unit and a variation width of the color deviation when the sign of the color deviation is inverted can be detected.