Dynamic Dithering Thresholds for Low-Bit-Depth Display Artifacts
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Solution Overview
Problem
Electronic displays with lower bit-depth capabilities often produce unsightly artifacts when performing traditional dithering techniques like Floyd-Steinberg dithering, especially with non-noisy or uniform image data, as these artifacts can remain visible for extended periods.
Innovation Solution
Dynamic dithering involves periodically varying a rounding threshold value used during the dithering process, causing artifacts to shift or disappear between frames, making them essentially invisible to the human eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If spatial dithering (e.g., Floyd-Steinberg) is used to convert higher-bit-depth image data to lower-bit-depth image data, then information from least significant bits is distributed to nearby pixels to conserve image information, but unsightly artifacts (grainy patterns) appear in the dithered image
Solution Approach 1:
The patent applies dynamics by making the rounding threshold value change over time rather than remaining static. The threshold value is updated for each frame or at specified intervals, causing the dithering pattern to shift dynamically. This temporal variation prevents fixed artifacts from persisting in the same location, as the rounding decisions change with each frame update.
Solution Approach 2:
The patent implements periodic action by systematically updating the rounding threshold value at regular intervals (e.g., each frame or every N frames). This periodic change in the threshold value creates a time-varying dithering pattern that distributes artifacts across different spatial locations over time, making them imperceptible to the human eye.
2Productivity
If a static rounding threshold value is used in dithering, then the dithering process is simple and computationally efficient, but artifacts remain in the same location across multiple frames making them visible
Solution Approach 1:
The patent introduces dynamics by transitioning from a static rounding threshold to a time-varying threshold that updates periodically. This dynamic approach maintains computational efficiency while eliminating persistent artifacts, as the threshold updates can be implemented with simple arithmetic operations on frame counters or time variables.
Solution Approach 2:
The patent applies parameter changes by modifying the rounding threshold value over time. The threshold parameter is systematically varied (e.g., incrementing modulo 2^N or using frame-number-based sequences) to change the rounding behavior dynamically, which disperses artifacts across different pixel locations across frames without requiring complex processing.
3Measurement precision
If dithering distributes least significant bit information to nearby pixels, then the lower-bit-depth image better represents the original higher-bit-depth image, but grainy artifacts become visible in uniform or non-noisy regions
Solution Approach 1:
The patent uses dynamics to make the dithering pattern time-varying by updating the rounding threshold periodically. This causes the distribution of quantization errors to shift across different spatial locations over time, transforming static grainy patterns into dynamic, moving artifacts that the human visual system cannot easily detect.
Solution Approach 2:
The patent implements periodic updates to the rounding threshold value, causing the dithering pattern to cycle through different states. This periodic variation ensures that any localized grainy artifacts appear only transiently at different locations across frames, preventing the formation of persistent visible patterns while maintaining accurate image representation.
Data Source
AI summary
Devices and methods for dynamic dithering are provided. For example, an electronic device according to an embodiment may include image processing circuitry that operates on higher-bit-depth image data and a display panel that displays lower-bit-depth image data. To obtain the lower-bit-depth image data, the image processing circuitry may perform dynamic dithering on the higher-bit-depth image data. Such dynamic dithering may involve dithering frames of the higher-bit-depth image data based at least in part on respective rounding threshold values.