Error Diffusion Dithering for Privacy LCDs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid crystal display (LCD) technologies that switch between public and private modes either compromise on image quality, incur additional complexity, or result in resolution loss, as they fail to maximize off-axis luminance for all on-axis luminance values and require pre-processing to minimize resolution loss in private mode.
Innovation Solution
The implementation of enhanced image processing methods in a multi-view LCD that involves control electronics receiving both main and side image data to produce a combined image, where on-axis viewers see the main image and off-axis viewers see the side image, with output data values selected to maintain target luminance and minimize error diffusion, using techniques like Floyd-Steinberg dithering without compromising the main image's resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If existing image processing methods are used to produce privacy effect, then off-axis image quality and privacy strength are improved, but the range of off-axis luminance values is not maximised for all on-axis luminance values and resolution loss occurs
Solution Approach 1:
The patent applies error diffusion dithering to transform the main image into a dithered version that, when viewed from off-axis angles, produces a maximized range of luminance values. This parameter transformation allows the off-axis viewer to perceive the side image with optimal contrast while the on-axis viewer sees the original main image with preserved resolution
Solution Approach 2:
The patent segments the display functionality into two distinct viewing paths: on-axis viewing preserves the original main image resolution, while off-axis viewing presents the dithered side image. This segmentation is achieved through error diffusion processing that creates different perceptual outcomes based on viewing angle
2Reliability
If existing image processing methods are used to produce privacy effect, then privacy strength is improved, but pre-processing is required which increases complexity and memory requirement
Solution Approach 1:
The patent performs error diffusion dithering as a preliminary processing step on the main image before it is displayed. This pre-dithering allows the privacy effect to be achieved without requiring complex real-time processing or additional memory, as the dithered pattern is already embedded in the displayed image
Solution Approach 2:
The patent replaces complex multi-step image processing algorithms with a simpler error diffusion dithering approach. This substitution maintains privacy effectiveness while significantly reducing computational complexity and memory requirements compared to other privacy enhancement methods
Data Source
AI summary
A display device includes control electronics and a pixilated liquid crystal (LC) panel. The control electronics receives inputs of main image data for a main image and side image data for a side image. The control electronics outputs combined image data combining the main and side images such that an on-axis viewer perceives from the combined image the main image, and an off-axis viewer perceives from the combined image the side image. The output image data comprises data values chosen from a set of available output data values for the pixels selected from multiple sets of available data values depending on at least on the side image data. For a pixel currently being processed, the output data value is chosen from the selected set of available output data values for which a resulting luminance value is closest to a target luminance value for the current pixel.