Color Trapping on Halftoned Bi-Level Bitmaps
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital imaging systems face challenges in color misregistration and engine artifacts, such as trailing edge detection, during the reproduction of complex digital documents, particularly in commercial printing presses where color halftone prints require precise registration to avoid white gaps and maintain image integrity.
Innovation Solution
A novel method for color trapping on halftoned bi-level bitmaps is introduced, which involves rigorous edge detection using pixel counts and orientation conditions, along with non-linear filtering to determine if a pixel resides on a two-color edge, preventing trapping in white regions and enabling asymmetrical and multi-pixel trapping along different dimensions to correct for misregistration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If color trapping is applied to halftoned bi-level bitmaps using conventional methods, then misregistration between colors can be compensated, but engine artifacts such as trailing edge detection occur where color intensity falls off sharply at the trailing edge
Solution Approach 1:
The patent applies parameter changes by using non-linear filtering to modify how color intensity is calculated at edges. Instead of linear averaging, the non-linear filter preserves sharp transitions while reducing artifacts, changing the mathematical parameters of edge detection to achieve both accurate trapping and artifact reduction
Solution Approach 2:
The patent implements local quality by applying different processing rules to different regions of the image. Specifically, it identifies two-color edges and applies specialized non-linear filtering only at these critical locations, while leaving other regions unchanged, thus improving edge accuracy without introducing artifacts in uniform areas
2Measurement precision
If rigorous edge detection using pixel counts and orientation conditions is implemented, then trapping in white regions is prevented and color accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the image processing into distinct stages: first identifying two-color edges using pixel count ratios, then applying non-linear filtering only to these identified edges. This segmentation allows rigorous edge detection without processing the entire image with full complexity, thus improving accuracy while managing computational load
Solution Approach 2:
The patent uses partial action by applying the computationally intensive non-linear filtering only to pixels identified as residing on two-color edges, rather than processing all pixels in the image. This partial application maintains high edge detection accuracy while significantly reducing overall computational complexity compared to full-image processing
Data Source
AI summary
What is disclosed is a novel system and method for determining whether a pixel resides along a two-color edge in a halftoned bi-level bitmap. In one embodiment, a bitmap having a plurality of colored pixels is received. For each pixel in the bitmap, a window of size n×m is defined centered on the current pixel. The window is partitioned into a plurality of regions with each region having an orientation direction with each orientation direction having an associated numeric value. A number of pixels are counted for each of the first and second colors in each of the associated orientation directions. A determination is made as to the respective orientation direction having the maximum and minimum pixel counts for each of the first and second colors. Thereafter, a determination is made whether the pixel resides along a two color edge based upon the max/min counts and each associated orientation direction.