Error Accumulation Dithering for Screen Door Artifact Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern graphics processing systems face challenges in generating images with high color resolution for display devices that have lower color resolution, often resulting in undesirable artifacts like the 'screen door' effect due to matrix-based dithering, and existing error forwarding algorithms are expensive to implement.
Innovation Solution
The proposed method employs error accumulation dithering, where the selection between high and low intensity colors for a pixel is based on an error term accumulated from previously processed pixels, using a device with an accumulator module, conversion module, and adjustment module to track and modify the error, thereby reducing the 'screen door' effect while being cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If matrix-based dithering is used to reduce color resolution, then color resolution is reduced to match display device capabilities, but visible screen door artifacts and scintillation effects occur
Solution Approach 1:
The patent applies dynamics by making the dither matrix values change over time through temporal modulation. The dither matrix is updated across multiple frames with different phase offsets, transforming the static pattern into a dynamic one that prevents the human eye from perceiving fixed screen door artifacts while maintaining color accuracy.
Solution Approach 2:
The patent implements periodic action by cycling through different dither matrix phases across frames. The dither matrix values are modulated periodically with a cycle equal to the number of bits being truncated, creating a temporal pattern that averages out visual artifacts while preserving the intended color representation.
2Object-affected harmful factors
If Floyd and Steinberg error forwarding algorithm is used to eliminate screen door effect, then screen door artifacts are reduced, but hardware implementation cost increases due to need for line store and frequent read-modify-write operations
Solution Approach 1:
The patent extracts only the essential error accumulation function needed to eliminate screen door artifacts, separating it from the complex line store infrastructure of the Floyd-Steinberg algorithm. By maintaining a simple accumulated error value in a register and updating it incrementally, the patent achieves artifact reduction without the hardware overhead of frequent read-modify-write operations on large memory structures.
Solution Approach 2:
The patent applies self-service by having the error accumulation logic work incrementally with each pixel processed, using only the previously accumulated error value and the current pixel's quantization error. This eliminates the need for external line store memory and complex coordination, allowing the system to serve itself with minimal hardware resources.
3Object-affected harmful factors
If dither matrix entries are rearranged on successive frames to avoid screen door effect, then screen door artifacts are reduced, but temporal resolution is blurred and visible flickering occurs
Solution Approach 1:
The patent changes the parameter being modulated from the dither matrix pattern itself (as in conventional approaches) to the accumulated error value that drives pixel selection. By modifying how the error accumulation is phased across frames rather than rearranging the entire dither matrix, the patent achieves artifact reduction with smoother temporal transitions and less visible flickering.
Data Source
AI summary
Error accumulation dithering is used to generate images of lower color resolution from input data of higher color resolution. A target color is received at high resolution for a current pixel of the image. The target color is intermediate between a first color and a second color at a low color resolution. One of the first color and the second color is selected as a final pixel color, based on whether an accumulated error determined from previous pixels is above or below a threshold amount. After selecting the final pixel color, an updated accumulated error is provided to the next pixel.