Halftone Table Reconstruction via Compressed PWM Coefficients
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Solution Overview
Problem
Laser printers and other printing devices face challenges in efficiently storing and utilizing specialized halftone information, leading to limitations in producing customized grey levels due to storage constraints, which restrict the use of advanced halftoning techniques.
Innovation Solution
A printing device component with a memory device stores compressed halftone data, including minimum and maximum PWM values, and a healing parameter that enforces monotonicity in PWM values, allowing for the reconstruction of halftone tables and enabling efficient use of halftoning techniques without requiring extensive storage of specialized halftone information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized halftone information is stored in detail, then halftoning accuracy is improved, but memory usage increases
Solution Approach 1:
The patent extracts only the essential halftone information (minimum and maximum PWM values, healing parameters) from the complete halftone data set, storing only these critical parameters in the memory device while deriving the rest during operation. This selective extraction reduces memory storage requirements while preserving the necessary accuracy for halftoning operations.
Solution Approach 2:
The patent changes the representation parameters of halftone data by storing compressed forms (minimum PWM, maximum PWM, healing parameters) instead of complete halftone tables. These parameter transformations enable efficient storage while allowing reconstruction of the full halftone information when needed, resolving the contradiction between storage efficiency and accuracy.
2Quantity of substance
If compressed halftone data is stored, then memory usage is reduced, but data reconstruction complexity increases
Solution Approach 1:
The patent performs preliminary organization of halftone data during the compression phase, structuring it with clearly defined parameters (minimum PWM, maximum PWM, healing parameters) that guide the reconstruction process. This preliminary structuring simplifies the reconstruction operation, making it a straightforward parameter application rather than a complex computational task.
Solution Approach 2:
The compressed halftone data structure is designed to be self-descriptive, containing all necessary information (min PWM, max PWM, healing parameters) within the stored data itself. This self-contained structure enables automatic reconstruction without requiring external reference tables or complex decoding algorithms, reducing reconstruction complexity while maintaining memory efficiency.
Data Source
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AI summary
A memory device (108) for a printing device component, the memory device (108) comprising: compressed coefficients (110) that, when decompressed by a printing device, form difference entries, wherein a difference entry of the difference entries represents a difference of a value of a corresponding entry of a halftone table and a value of a corresponding entry of a reference table (122); and healing parameter values (114) specifying a healing process to apply to a reconstructed halftone table produced using the coefficients, wherein the coefficients and the healing parameter values (114) are accessible by the printing device to reconstruct a halftone table used in halftone printing by the printing device.