Printer Colorant Calibration via LUT Interpolation
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Solution Overview
Problem
Conventional color calibration methods for printing systems, such as the Halftone Area Neugebauer Separation (HANS) system, require numerous and costly measurements to account for drop weight variations in colorant dispensation, leading to inefficiencies and increased complexity.
Innovation Solution
A method utilizing pre-computed boundary look-up tables (LUTs) and a closed-loop color system to interpolate and generate a calibrated LUT, reducing the need for extensive calibration measurements by compensating for drop weight changes through measured drop weight values, thereby efficiently controlling colorant dispensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional color calibration methods (HANS system) are used to account for drop weight variations, then color accuracy is improved, but the number of measurements and system complexity increase significantly
Solution Approach 1:
The patent segments the continuous drop weight variation into discrete boundary classes (e.g., first boundary class and second boundary class). Pre-computed LUTs are generated for each boundary class separately, allowing the system to handle different drop weight scenarios independently and then interpolate between them, reducing the overall calibration complexity while maintaining color accuracy.
Solution Approach 2:
The patent performs preliminary computation of boundary LUTs for different drop weight boundary classes before actual calibration is needed. These pre-computed LUTs store the relationship between colorant amounts and color values for extreme cases, enabling rapid interpolation during operation without requiring extensive real-time measurements.
2Manufacturing precision
If extensive calibration measurements are performed to compensate for environmental conditions and printer usage, then color control is improved, but calibration time and cost increase
Solution Approach 1:
The system pre-computes boundary LUTs covering the full range of expected environmental conditions and printer usage scenarios. This preliminary action ensures that when calibration is actually performed, the system can quickly interpolate between pre-computed boundary cases rather than performing extensive real-time measurements, significantly reducing calibration time while maintaining color control.
Solution Approach 2:
The patent implements a dynamic calibration approach where the system measures actual drop weight and selects or interpolates between appropriate pre-computed boundary LUTs based on the measured values. This dynamic selection and interpolation process adapts to current conditions without requiring full re-calibration, reducing time loss while maintaining accuracy.
3Productivity
If pre-computed boundary LUTs with interpolation are used, then calibration efficiency is improved, but measurement precision requirements increase
Solution Approach 1:
The patent incorporates feedback by measuring actual drop weight values and using these measurements to select or interpolate between appropriate pre-computed boundary LUTs. The measured drop weight values serve as feedback that guides the selection of the most appropriate boundary class and determines the interpolation weights, ensuring accurate color reproduction while maintaining calibration efficiency.
Data Source
AI summary
A system includes a memory to store pre-computed boundary look-up tables (LUTs) for respective drop weight boundary classes of a printer having a plurality of colorants. Each pre-computed boundary LUT provides one Neugebauer Primary area coverage (NPac) for each node of the LUT in response to a device color input value that corresponds to each node. Measurement data stored in the memory represent measured drop weight values for the plurality of different colorants of the printer. A processor executes instructions that interpolate among the pre-computed LUTs based on the measured drop weight values to determine a proportional weighting of each of the pre-computed LUTs.