Halo Artifact Reduction in Electrophotographic Printing via Edge Dilation
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Solution Overview
Problem
Electrophotographic printing systems face challenges in reducing halo artifacts caused by fringe field effects, which result in uneven toner deposition across image edges, leading to noticeable tone reproduction variations.
Innovation Solution
A method involving a data processing system that analyzes input images to create an edge map, performs edge region dilation, and modifies pixel values in the input image to correct for halo artifacts, thereby reducing their visibility during printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrophotographic printing systems use uniform charging and exposure methods, then the printing process is simple and efficient, but halo artifacts appear at image edges due to fringe field effects
Solution Approach 1:
The patent applies local quality by differentiating the exposure treatment between edge regions and non-edge regions. Specifically, pixels identified as being in light-side edge regions receive enhanced exposure (added pixel values) while other pixels use standard exposure, thereby locally correcting the fringe field effect only where needed without affecting the entire image processing pipeline.
Solution Approach 2:
The patent implements preliminary action by performing edge detection and identifying light-side edge region pixels before the actual printing exposure. This pre-processing step creates a corrected image with adjusted pixel values that compensate for anticipated halo artifacts, ensuring the correction is applied in advance during the image processing stage rather than requiring post-printing adjustment.
2Manufacturing precision
If image processing is performed to correct halo artifacts by analyzing and modifying pixel values, then edge tone reproduction accuracy improves, but processing time and computational complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the image processing into distinct stages: edge detection to identify edge pixels, classification of pixels into light-side edge regions versus other regions, and selective modification of only the identified edge pixels. This segmented approach focuses computational resources only on the problematic edge regions rather than processing the entire image uniformly.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting pixel values based on their spatial location and edge characteristics. Specifically, the exposure parameter (pixel value) is modified for light-side edge region pixels by adding a compensation value, while other pixels retain their original values, thereby achieving precise edge correction with minimal overall processing overhead.
3Manufacturing precision
If dilation operations are performed on edge regions to expand the correction area, then halo artifact coverage is improved, but processing complexity and computation time increase
Solution Approach 1:
The patent applies partial action by performing dilation operations selectively only on the identified light-side edge regions rather than on the entire image. This targeted approach expands the correction area precisely where halo artifacts occur (on the light side of edges) without unnecessarily processing other image regions, thereby achieving adequate artifact coverage with controlled computational complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces the visibility of halo artifacts and can be implemented in real-time by the printing system, ensuring consistent and controlled edge region adjustments based on the printing configuration.
Implementation Method 1
an electrostatic latent image is formed on a photoreceptor by uniformly charging the photoreceptor and then discharging selected areas of the uniform charge to yield an electrostatic charge pattern corresponding to the desired image
Implementation Method 2
charged toner particles are brought into the vicinity of the photoreceptor and are attracted to the latent image to develop the latent image into a toner image
Implementation Method 3
A suitable electric field is applied to transfer the toner particles of the toner image to the receiver to form the desired print image on the receiver
Data Source
AI summary
A method for processing an input image to reduce halo artifacts in an electrophotographic printing system. The input image is automatically analyzed to determine an edge map image indicating light-side edge regions that include edge pixels that are adjacent to edge transitions in the input image and are on a lighter side of the edge transition. At least one edge region dilation operation to the edge map image to expand the light-side edge regions in a direction away from the edge transitions. A corrected image is formed by modifying the input pixels of the input image corresponding to the expanded light-side edge regions to determine corrected pixels having corrected pixel values. The corrected image is then printed using the electrophotographic printing system.