Dithering Video Data for Display Intensity Resolution
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Solution Overview
Problem
Existing display driving technologies face limitations in accurately displaying intensity values on pixels, leading to restricted displayable intensity levels and visual artifacts such as flicker and contouring, due to the binary nature of digital LCDs and the non-linear electro-optical response of some displays.
Innovation Solution
A system and method that converts binary video data into a higher resolution compound data type with dither bits to apply various dithering schemes, allowing for finer adjustments in intensity levels and phase-shifting temporally dithered data based on pixel location to reduce visual artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temporal dithering is used to display intermediate intensity levels, then intensity resolution is improved, but the number of displayable intermediate intensities is limited to the number of frames over which data is dithered
Solution Approach 1:
The patent transitions from temporal dithering (time-based) to spatial dithering (space-based) by distributing different intensity values across multiple pixels within the same frame. Instead of varying intensity over time for a single pixel, the invention varies intensity across spatially adjacent pixels, thereby achieving finer intensity resolution without being constrained by frame count.
Solution Approach 2:
The patent divides a single pixel's intensity representation into multiple discrete pixel elements within a pixel group. By segmenting the intensity display function across multiple pixels (e.g., 4 pixels representing 16 intensity levels), the system achieves higher intensity resolution than would be possible with temporal dithering alone.
2Measurement precision
If spatial dithering is used to achieve intermediate intensity levels, then intensity resolution is improved, but image resolution is sacrificed
Solution Approach 1:
The patent segments the display into pixel groups where each group contains multiple pixels that collectively represent a single intensity value. By organizing pixels into groups (e.g., 2x2 or larger groups) and applying dithering patterns within these groups, the system achieves fine intensity control while maintaining the perceived spatial resolution through the grouping structure.
Solution Approach 2:
The patent applies different dithering patterns and intensity distributions to different regions within pixel groups based on local requirements. Each pixel within a group can have customized intensity values tailored to achieve the desired overall intensity while maintaining spatial coherence and avoiding visible artifacts.
3Measurement precision
If dithering is applied to display intermediate intensity values, then intensity accuracy is improved, but visual artifacts such as flicker and contouring appear
Solution Approach 1:
The patent employs periodic dithering patterns that cycle through different intensity distributions across pixel groups in a systematic manner. By using regular, repeating patterns rather than random variations, the system achieves average intensity accuracy while minimizing flicker and contouring artifacts through the predictability and uniformity of the periodic action.
Solution Approach 2:
The patent pre-calculates and stores optimal dithering patterns in lookup tables before display. By preparing dithering sequences in advance based on desired intensity values, the system can directly apply pre-optimized patterns that minimize visual artifacts, rather than computing dithering sequences in real-time during display operation.
Data Source
AI summary
A novel method for driving a display device includes the steps of receiving video data of a first type, converting the video data to data of a second type, dithering the data of the second type to form dithered pixel data, and outputting the dithered pixel data. The step of converting the video data to data of a second type includes inserting dither bits indicative of a particular dithering scheme into the data of the second type. An example display driver circuit includes an input for receiving video data, a data converter coupled to receive the video data and operative to convert the video data into pixel data to be written to pixels of a display, and a ditherer operative to receive the pixel data and to dither the pixel data to generate dithered pixel data. The video data is data of a first type, and the pixel data is data of a second type, different from the first type. In the disclosed example, the first type of data includes a binary data word, and the second type of data includes a compound data word. The compound data word includes a first set of binary weighted bits, a second set of arbitrarily weighted bits, and dither bits.