Electrophoretic Display Dither Compensation for Ghosting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrophoretic display systems face limitations in achieving a large number of gray tone levels due to edge artifacts caused by differential blooming, which result in ghosting effects when transitioning between images, especially when the prior display state is arbitrary.
Innovation Solution
A method and apparatus that compensate for differential blooming by using a dither pattern based on the previous image level to determine the current image level, employing a lookup table and dither mask array to adjust pixel output values, thereby reducing or eliminating ghosting effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If half-toning is used to increase the number of gray tone levels, then the display appears to have more gray tone levels, but edge artifacts such as differential blooming and ghosting are introduced
Solution Approach 1:
The patent applies preliminary action by using the previous frame's dither pattern to pre-compensate for edge artifacts in the current frame. The lookup table is pre-computed with correction values based on historical dither patterns, allowing the system to anticipate and correct differential blooming before it manifests as visible ghosting artifacts.
Solution Approach 2:
The patent implements feedback by using the previous frame's dither pattern index as input to determine the current frame's dither pattern. This creates a feedback loop where historical display state information is continuously fed back into the half-toning process to compensate for artifacts, with the lookup table serving as the feedback mechanism that maps previous states to corrected current states.
2Measurement precision
If conventional input mapping is used to compensate for edge artifacts, then tone reproduction is improved for fixed prior states, but compensation fails when the prior display state is arbitrary
Solution Approach 1:
The patent applies dynamics by making the dither pattern selection adaptive rather than static. Instead of using a fixed input mapping, the system dynamically selects dither patterns based on the previous frame's actual display state. The lookup table provides dynamic compensation values that change according to the historical dither pattern index, allowing the system to adapt to arbitrary prior states rather than requiring fixed predetermined states.
Solution Approach 2:
The patent changes parameters by using the previous dither pattern index as a variable input parameter for selecting the current dither pattern. This parameter change approach allows the compensation mechanism to respond to different display states by selecting appropriate dither patterns from the lookup table, rather than relying on a single fixed mapping relationship.
Data Source
AI summary
Methods and apparatus for image processing are provided. A method for image processing includes: (a) accessing, in a lookup table, a current pattern index for a current pixel based on a current pixel input value and a previous pattern index; (b) accessing, in a dither mask array, a threshold value for the current pixel based on a location of the current pixel; (c) comparing the current pattern index with the threshold value; (d) determining a current pixel output value for activation of the current pixel based on a result of the comparing; (e) storing the current pattern index to serve as the previous pattern index for a next image; and (f) repeating acts (a)-(e) for each pixel in the image.