Automated Color Adjustment via Local Gradient Approximation
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Solution Overview
Problem
Current proofing systems for high volume output devices face challenges in achieving consistent color reproduction due to variations in ink, paper, and printing conditions, leading to inaccurate color matching between digital color printers and high volume output devices, and require frequent manual interventions for calibration.
Innovation Solution
A method that adjusts digital-image colorant combinations by rendering output colors at base points and gradient points in input colorant space, using a spectrophotometer to measure and derive a linear approximation of color changes, allowing for automatic and accurate calibration to achieve a reference output color within a predetermined tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If digital color printers are used to print proofs, then cost effectiveness is improved, but color accuracy deteriorates due to variations in ink, paper and printing conditions
Solution Approach 1:
The system changes the parameters of the digital color printer by adjusting colorant combinations based on measured deviations. A spectrophotometer measures actual printed colors, and the system modifies the digital image colorant combinations to compensate for variations in ink, paper, and printing conditions, thereby maintaining color accuracy while using cost-effective digital printers for proofing
Solution Approach 2:
The system implements a feedback loop where a spectrophotometer measures the actual colors printed by the digital color printer, compares them to reference colors, and automatically adjusts the colorant combinations to correct deviations. This closed-loop feedback mechanism ensures color accuracy is maintained despite variations in printing conditions
2Measurement precision
If manual stand-alone calibration devices are used to measure colors, then measurement capability is provided, but automation is reduced requiring frequent manual interventions
Solution Approach 1:
The system enables self-service automation by integrating a spectrophotometer and control system that automatically measure printed colors, compare them to reference values, calculate required adjustments, and modify colorant combinations without human intervention. The system performs its own calibration and color correction tasks autonomously
Solution Approach 2:
The system merges the calibration device (spectrophotometer) with the digital color printer and control system into an integrated automated color management system. This combination allows the measurement, analysis, and correction functions to work together seamlessly, eliminating the need for separate manual calibration operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables rapid and accurate color adjustments, reducing manual interventions and improving color consistency by accounting for local variations in the color space, ensuring that the digital-image colorant combinations produce the desired reference output color.
Implementation Method 1
A spectrophotometer measures the reflectance and/or transmittance of an object at a number of wavelengths throughout the visible spectrum. More specifically, a spectrophotometer exposes a test image to a known light source and then analyzes the light that is reflected by the test image to determine the spectral intensity.
Implementation Method 2
A spectrophotometer exposes a test image to a known light source and then analyzes the light that is reflected by the test image
Data Source
AI summary
A method for determining (250) a change required in a selected base point in an input colorant space of a digital-image rendering system to obtain from the digital-image rendering system a desired reference output color to within a predetermined color tolerance comprises determining the required change based on a local approximation of the colorant/color relationship at the selected base point. Gradient points are automatically generated (210) that are proximate or coincident with the selected base point and that are different from any other base point than the selected base point. A linear approximation to the colorant/color relationship at the selected base point is computed (240) from the gradient points and the measured (230) output colors at the gradient points as rendered (220) by the digital-image rendering system and. The required change is determined from the local gradient of the colorant/color relationship at the selected base point.