Alpha Blending Unit for Head Shading Correction in Inkjet Printers
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Solution Overview
Problem
Existing image processing techniques for inkjet printers face challenges in efficiently performing head shading corrections across multiple nozzle arrays, leading to degradation in processing performance and increased circuit complexity due to frequent table switching and compromised correction accuracy.
Innovation Solution
An image processing apparatus equipped with an alpha blending unit that performs alpha blending of first and second head-shaded images, switching coefficients for alpha blending on a per-line basis to optimize head shading corrections across multiple nozzle arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple HS tables are arranged for different nozzle arrays in multi-pass printing, then correction accuracy is improved, but device complexity and processing load increase
Solution Approach 1:
The invention segments the image data into multiple bands (e.g., upper half and lower half) and assigns different HS tables to each band. This allows accurate correction for different nozzle arrays in multi-pass printing without requiring separate HS tables for every possible pass combination, thereby reducing overall system complexity while maintaining correction accuracy.
Solution Approach 2:
The invention applies local quality by assigning specific HS tables to specific bands based on the nozzle array characteristics for each pass. Each band receives the appropriate HS table for its corresponding nozzle array, enabling accurate local correction without the need for a complete set of HS tables for all passes, thus reducing device complexity.
2Measurement precision
If HS tables are switched frequently for different nozzle arrays, then correction accuracy is improved, but processing performance degrades
Solution Approach 1:
By segmenting the image into bands and pre-assigning HS tables to each band, the invention reduces the frequency of table switching during processing. The processor can continuously work on a band without needing to switch tables mid-processing, thereby maintaining correction accuracy while improving processing performance.
Solution Approach 2:
The invention performs preliminary action by pre-determining which HS table should be applied to each band before processing begins. This pre-assignment eliminates the need for dynamic table switching during the actual processing, maintaining correction accuracy while significantly improving processing speed and performance.
3Measurement precision
If multi-pass printing with different HS tables is implemented, then correction accuracy is improved, but processing time increases
Solution Approach 1:
The invention segments the printing process into bands with predetermined HS tables, allowing parallel processing of different bands. This segmentation enables the system to process multiple regions simultaneously without waiting for table switching, thereby reducing total processing time while maintaining accurate correction through proper HS table assignment to each band.
Solution Approach 2:
By performing preliminary assignment of HS tables to bands before processing, the invention eliminates time-consuming table switching operations during the actual printing process. The processor can continuously generate corrected image data for each band without interruptions, significantly reducing processing time while preserving correction accuracy.
Data Source
AI summary
An image processing apparatus includes an alpha blending unit configured to perform alpha blending of a first image obtained through first head shading on a band image which is an image in units of band and a second image obtained through second head shading on the first image. The alpha blending unit switches a coefficient for the alpha blending for each line of the band image.