Calibrated HANS LUT for Drop Weight Deviation
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Solution Overview
Problem
Conventional color calibration methods for printing systems require numerous and costly measurements, especially for advanced systems like Halftone Area Neugebauer Separation (HANS), which are inefficient and resource-intensive, particularly due to variations in drop weight affecting colorant deposition.
Innovation Solution
A method and system using calculated drop weight look-up tables (LUTs) to derive a small number of parameters for N colorant channels, generating a calibration element to compute a calibrated LUT that adjusts for drop-weight changes, ensuring color accuracy without introducing new Neugebauer Primary areas outside the original LUT domain, employing a measuring device and processor to measure and process drop weights, and applying a calibration calculator to generate a calibrated LUT for efficient color calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color calibration methods are used for HANS printing systems, then color accuracy can be achieved, but numerous and costly measurements are required
Solution Approach 1:
The patent extracts the core calibration information by deriving a small number of parameters (N parameters for N colorant channels) that represent drop-weight changes. Instead of performing numerous comprehensive measurements, the method extracts essential calibration data from limited measurements and uses these parameters to generate a calibration LUT, thereby reducing measurement complexity while maintaining color accuracy.
Solution Approach 2:
The patent changes the calibration approach by representing drop-weight variations through N parameters (one per colorant channel) rather than through full colorimetric measurements. These parameters describe the magnitude and direction of drop-weight changes, enabling efficient calibration with fewer measurements while preserving color accuracy through mathematical modeling of the deviations.
2Manufacturing precision
If comprehensive calibration measurements are performed, then color control is improved, but time and resources are consumed
Solution Approach 1:
The patent performs preliminary calibration by measuring drop weights once and deriving N parameters that characterize drop-weight deviations. These parameters are then applied to generate a calibration LUT that compensates for variations. This preliminary action establishes a reusable calibration model that maintains color control without requiring repeated comprehensive measurements, thereby reducing calibration time.
Solution Approach 2:
The patent creates a simplified calibration model by copying the essential calibration information into N parameters that represent drop-weight changes. Instead of storing or re-measuring full colorimetric data, the method uses these compact parameter representations to generate calibration corrections, efficiently preserving color control while minimizing time investment.
3Reliability
If advanced HANS halftoning is used, then color reproduction is enhanced, but sensitivity to drop-weight variations increases
Solution Approach 1:
The patent implements feedback by measuring actual drop weights and deriving calibration parameters that compensate for deviations from nominal values. The calibration LUT uses these parameters to adjust halftone instructions, creating a closed-loop system that counteracts the sensitivity of HANS to drop-weight variations and maintains reliable color reproduction despite manufacturing tolerances.
Solution Approach 2:
The patent applies preliminary anti-action by pre-calculating compensation values in the calibration LUT based on measured drop-weight variations. Before actual printing occurs, the system determines the magnitude and direction of drop-weight deviations and generates corrective halftone instructions that anticipate and counteract the harmful effects of these variations on color reproduction.
Data Source
AI summary
A system includes a memory to store at least one Halftone Area Neugebauer Separation (HANS) look-up table (LUT) that represents a predetermined drop weight for N colorant channels of a printer. The HANS LUT provides a given Neugebauer Primary area coverage in response to a device color input value. Measurement data stored in the memory represents measured drop weight values for the N colorant channels of the printer. A processor executes instructions stored in the memory. The instructions are to compute a calibration element for the HANS LUT that describes a drop-weight deviation with respect to the HANS LUT based on the measured drop weight values. The instructions are to apply the calibration element to at least a portion of the HANS LUT to generate a calibrated LUT.