Background Suppression in Color Scanning via Luminance-Chrominance Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for background suppression in color scanning and copying systems face challenges, particularly in accurately identifying and adjusting chrominance values for pixels with grayscale levels lower than white, leading to color shifts and artifacts.
Innovation Solution
A method that converts RGB images to luminance-chrominance color space, determines background pixels by comparing luminance and chrominance values to adjustable thresholds, and adjusts chrominance values using a predefined table to ensure smooth background suppression without affecting image color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If background suppression is performed by mapping each channel's white pixel value to 255 separately in RGB channels, then background suppression is achieved, but color artifacts are introduced and processing complexity increases
Solution Approach 1:
The patent introduces luminance-chrominance color space as an intermediary representation between RGB input and final output. By converting to luminance (L) and chrominance (a, b) components, the method separates brightness information from color information, allowing independent processing of background suppression in luminance while preserving chrominance integrity, thus avoiding color artifacts
Solution Approach 2:
The patent changes the color space parameters from RGB to luminance-chrominance (Lab or Luv). This parameter transformation enables different processing strategies: luminance channel for background detection and suppression, and chrominance channels for color preservation. The selective adjustment of luminance without proportional adjustment of chrominance prevents the color shifts that occur when all channels are mapped to 255
2Device complexity
If luminance channel alone is suppressed for background suppression, then processing is simplified, but background suppression is incomplete due to chrominance channel variations
Solution Approach 1:
The patent applies different processing quality to different components: full suppression is applied to the luminance channel where background pixels are identified, while chrominance channels receive selective or no adjustment. This local differentiation ensures complete background suppression in luminance while maintaining color accuracy through preserved chrominance information, achieving both simplicity and completeness
3Reliability
If chrominance channels are adjusted independently of luminance and each other, then background suppression is enhanced, but color shifts occur in some regions
Solution Approach 1:
The patent merges the processing of luminance and chrominance channels under a unified background detection framework. Background pixels are identified using luminance thresholding, and then both luminance and chrominance adjustments are applied consistently to these identified background regions. This combined approach ensures that chrominance adjustments only occur where luminance indicates background, preventing color shifts in foreground regions and maintaining overall color consistency
Data Source
AI summary
An original image is received in a red-green-blue color space. Pixels in the original image are converted to a luminance-chrominance color space. Background pixels in the original image are determined by comparing a luminance value of each pixel to a selectable luminance threshold, and comparing chrominance value of each pixel to a predetermined chrominance threshold. Chrominance values of the background pixels in each chrominance channel are adjusted.