Dithering Method Prevents Gray Level Saturation in High Luminance Regions
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Solution Overview
Problem
Conventional dithering methods, such as temporal/spatial compensation, often result in gray level saturation, especially in high luminance regions, leading to unstable expression of high luminance parts and loss of detail in image output systems.
Innovation Solution
A dithering method employing temporal/spatial compensation combined with spatial compensation using optimized dither matrices and gamma voltage selection, where a head bit is added to the data and gamma voltages are selected to prevent overflow and ensure all gray levels are expressed without saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temporal/spatial compensation scheme is applied to reflect lower 2 bits onto pixels and lines, then the output data can express gray levels closer to the original 8-bit data, but gray level saturation occurs in high luminance regions causing unstable expression of high luminance parts
Solution Approach 1:
The patent segments the gray level range into multiple regions (first gray level region and second gray level region) with different compensation strategies. For the first region (lower luminance), temporal/spatial compensation is applied to reflect lower 2 bits. For the second region (high luminance), a different compensation method is used to prevent saturation. This segmentation allows each region to be processed optimally without causing saturation in high luminance areas.
Solution Approach 2:
The patent applies different compensation methods to different local regions of the image data. Specifically, it distinguishes between pixels in the first gray level region (0-247) and second gray level region (248-255), applying temporal/spatial compensation only where appropriate and using alternative methods for high luminance regions to prevent saturation while maintaining local optimization.
2Device complexity
If lower 2 bits are discarded through truncation scheme, then the device complexity is reduced and processing is simplified, but false contour lines are generated at boundaries due to loss of gray level discrimination
Solution Approach 1:
The patent introduces temporal/spatial compensation as an intermediary process between the truncation of lower 2 bits and the final output. This compensation mechanism acts as a mediator that reflects the discarded lower 2 bits back into the output data through temporal and spatial effects, thereby recovering gray level discrimination that would otherwise be lost in simple truncation.
Solution Approach 2:
The patent employs periodic temporal compensation by applying compensation patterns across multiple frames (first frame, second frame, third frame, fourth frame). This periodic action allows the system to reconstruct lost gray level information through temporal averaging and spatial reflection over multiple time steps, preventing false contour lines while maintaining manageable complexity.
3Manufacturing precision
If dithering is performed to smooth false contour lines by intentionally inputting noises to data, then image quality is improved by eliminating obvious contour lines, but data loss increases and original gray level information is degraded
Solution Approach 1:
The patent converts the harmful effect of discarding lower 2 bits (which causes false contour lines) into a beneficial process by applying temporal/spatial compensation. Instead of simply accepting the loss and using dithering to mask it, the system reflects the discarded bits back through compensation mechanisms, transforming the information loss into recovered gray level data that eliminates false contour lines without degrading original information.
Data Source
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AI summary
A dithering method prevents the gray level saturation in a gray level region having high luminance and expresses all gray levels. The dithering method includes performing the temporal/spatial compensation (S40) on input data, generating dithering data (S50) by adding a head bit to the data on which the temporal/spatial compensation is performed, and selecting a corresponding gamma voltage (S60) according to the dithering data.