Image Processing Circuit Differential Gray Level Shift
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Solution Overview
Problem
Conventional image processing methods for high dynamic range (HDR) displays fail to accurately reflect perceived brightness characteristics, leading to a narrower dynamic range than human sight and potential artifacts due to uneven gray level distribution, particularly affecting middle gray levels.
Innovation Solution
An image processing circuit and method that performs a differential shift of gray levels based on perceived darkness and brightness picture levels, using a luminance component extractor, histogram analyzer, perceived brightness calculator, differential shifter, and differential extension unit to adjust gray levels, ensuring accurate brightness representation and histogram extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If APL or brightness enhancement weight is used to stretch the histogram, then the dynamic range is widened, but perceived brightness characteristics according to gray level distribution are not reflected
Solution Approach 1:
The patent applies different processing strategies to different gray level regions. Low gray levels are shifted differentially based on PDPL (perceived darkness picture level), while high gray levels are extended differentially based on PBPL (perceived brightness picture level). This local differentiation ensures that perceived brightness characteristics are preserved while still achieving dynamic range expansion.
Solution Approach 2:
The patent changes the processing parameters dynamically based on the input image characteristics. By calculating PDPL and PBPL from the histogram and applying different differential shift/extension amounts to different gray level ranges, the system adapts the histogram processing to match human perception characteristics while expanding the displayable dynamic range.
2Illumination intensity
If the histogram is stretched by applying APL to all gray levels, then the dynamic range is widened, but middle gray levels are not stretched and inflection points occur
Solution Approach 1:
The patent divides the gray level range into different regions (low gray levels and high gray levels) and applies different processing operations to each region. Low gray levels undergo differential shifting based on PDPL, while high gray levels undergo differential extension based on PBPL. This prevents the inflection points that occur when a single APL-based stretching is applied uniformly.
Solution Approach 2:
The histogram processing is segmented into multiple operations: differential shifting for low gray levels and differential extension for high gray levels. Each segment is processed with appropriate parameters (PDPL for darkness, PBPL for brightness) to ensure smooth transitions and avoid inflection points between regions.
3Illumination intensity
If conventional histogram stretching is applied, then the dynamic range is increased, but artifacts appear in the images due to inflection points
Solution Approach 1:
By applying different differential processing operations to different gray level regions (shifting for low gray levels, extension for high gray levels), the patent avoids the uniform stretching that creates inflection points and subsequent artifacts. Each region is processed with parameters optimized for its characteristics, ensuring smooth gray level transitions.
Solution Approach 2:
The system calculates PDPL and PBPL from the input image histogram and uses these calculated values to determine the differential shift and extension amounts. This feedback mechanism ensures that the processing adapts to the actual gray level distribution, preventing artifacts while maximizing dynamic range expansion.
Data Source
AI summary
Disclosed are an image processing circuit and image processing method which is capable of enhancing gray level presentation, and a display device using the same. The image processing circuit and image processing method performs a differential extension of each gray level to a higher gray level with respect to a perceived brightness picture level (PBPL) reflecting a distribution of high gray levels of the input image, and then overdrives a light emitting device in the region of high gray levels higher than or equal to the threshold gray level.