Multi-bit Halftone Tone Value Compensation in Inkjet Printing
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Solution Overview
Problem
Existing methods for compensating tone value fluctuations in inkjet printing either require recalculation of the halftone image or result in artifacts due to arbitrary adaptations during the printing process, leading to inefficient correction and image quality deterioration.
Innovation Solution
A method that generates a multi-bit halftone image during the preprint process, using additional binary values to mark pixels for correction, which are ignored in regular mode but applied in correction mode to adjust ink drop sizes, ensuring accurate compensation without recalculating the halftone image and minimizing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the halftone image is manipulated during printing to compensate for tone value fluctuations, then tone value compensation is achieved, but artifacts are created that deteriorate print image quality
Solution Approach 1:
The patent applies preliminary action by embedding compensation data into the halftone image during the preprint screening process. Instead of manipulating the halftone image during printing, the system pre-calculates and embeds compensation information that guides the printing machine to automatically adjust ink drop sizes, thereby avoiding artifacts while achieving tone value compensation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a compensation data layer that acts as a mediator between the halftone image and the printing process. This compensation data, embedded in the halftone image, instructs the printing machine on how to adjust ink drop sizes without directly manipulating the halftone pixels, thus avoiding artifact creation while achieving the desired compensation effect.
2Manufacturing precision
If the halftone image is recalculated to compensate for tone value fluctuations, then accurate compensation is achieved, but computing time increases significantly
Solution Approach 1:
The patent applies preliminary action by performing the compensation calculation during the preprint screening process rather than during actual printing. The compensation data is embedded into the halftone image in advance, allowing the printing machine to simply follow pre-calculated instructions without requiring time-consuming recalculations during production.
Solution Approach 2:
The system applies self-service by making the halftone image self-containing with embedded compensation data. The halftone image carries its own compensation instructions, eliminating the need for external recalculation systems or additional computing resources during the printing process, thus maintaining high compensation accuracy without increasing computing time.
3Productivity
If additional binary values are introduced in the multi-bit halftone image, then compensation information is transmitted without recalculating halftone, but the printing machine must operate in a special correction mode
Solution Approach 1:
The patent applies universality by designing a multi-functional bit value system where each binary value in the multi-bit halftone image serves dual purposes: it encodes both the ink drop size information and the compensation instructions. This allows the printing machine to process compensation data using the existing multi-bit screen format without requiring fundamentally different processing modes, thereby maintaining productivity while preserving mode flexibility.
Data Source
AI summary
A method for compensating tone value fluctuation in inkjet printing includes generating multi-bit halftone images of pixels on a computer during prepress screening for color separations with multiple tone values out of print image data, forwarding multi-bit halftone images to a control unit of an inkjet printing machine, and printing the multi-bit halftone on the machine, wherein encoded binary values of multi-bit halftone images correspond to ink drop sizes to be generated by the machine. The computer introduces additional binary values of multi-bit halftone images not corresponding to ink drop sizes in pixel positions of multi-bit halftone images where occurring tone value fluctuations are to be compensated for by modified ink drop sizes, causing additional binary values to be ignored by the machine in a regular print mode, and assigning additional binary values to modified ink drop sizes in a correction print mode.