Adaptive HDR Compression Curves for Frame-Level Luminance Mapping
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Solution Overview
Problem
Existing HDR technologies face issues with inconsistent dynamic range compression across different display devices and unsatisfactory visual perception due to fixed compression ratios and inefficient luminance encoding, leading to poor representation of bright and dark details.
Innovation Solution
A method for dynamic range compression that involves frame-by-frame histogram statistics to determine an adaptive compression curve based on overall compression ratios and mid luminance information, using a combination of straight lines and Bezier curves to adjust the shape of the compression curve for each image frame, ensuring accurate representation of bright and dark details.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed compression ratios are used for HDR processing, then encoding simplicity is maintained, but visual perception quality deteriorates due to inconsistent dynamic range compression across different display devices
Solution Approach 1:
The patent applies dynamics by transitioning from fixed compression ratios to adaptive compression curves that adjust based on scene luminance characteristics. The compression curve is dynamically determined through histogram statistics analysis of each image frame, allowing the system to adapt to different luminance distributions while maintaining encoding efficiency through parameterized curve representation.
Solution Approach 2:
The patent changes parameters by using histogram statistics (mean luminance, standard deviation, skewness) to determine compression curve parameters. Instead of using a fixed compression ratio, the system varies compression curve parameters based on statistical analysis of the image frame's luminance distribution, enabling adaptive optimization for different display devices and scene conditions.
2Manufacturing precision
If adaptive compression curves based on histogram statistics are used, then visual perception quality is improved, but encoding complexity increases
Solution Approach 1:
The patent applies preliminary action by performing histogram statistics analysis before determining the compression curve. The system pre-calculates luminance distribution characteristics (mean, standard deviation, skewness) and uses these statistics to select or generate appropriate compression curves, avoiding the need for complex real-time adjustments during encoding.
Solution Approach 2:
The patent manages encoding complexity by changing to a parameterized approach where compression curves are defined by a limited set of parameters derived from histogram statistics. This reduces the complexity of storing and processing full compression curves while maintaining the benefits of adaptive optimization.
3Manufacturing precision
If compression curves are adjusted for each image frame, then detail representation in bright and dark regions is improved, but processing time increases
Solution Approach 1:
The patent applies segmentation by dividing the luminance range into different regions (bright and dark regions) and applying different compression strategies to each region through the compression curve. The histogram statistics allow the system to identify and separately optimize the compression characteristics for different luminance regions, preserving details in both bright and dark areas simultaneously.
Solution Approach 2:
The patent reduces processing time by performing preliminary histogram statistics analysis that captures the essential luminance distribution characteristics. This pre-analysis enables the selection of pre-defined compression curves or generates simplified curve parameters without requiring complex frame-by-frame optimization, thus reducing overall processing time while maintaining detail representation.
4Manufacturing precision
If HDR processing with high resolution and wide color gamut is implemented, then image quality is improved, but compatibility with standard display devices deteriorates
Solution Approach 1:
The patent applies local quality by applying different compression characteristics to different luminance regions of the image. The compression curve is designed to preserve quality in regions where the display device can reproduce them accurately while applying more aggressive compression in regions that would exceed the display device's capabilities, thus optimizing both image quality and compatibility.
Solution Approach 2:
The patent achieves compatibility through parameter changes by adjusting compression curve parameters based on the display device's luminance range and characteristics. The system transforms HDR content with high resolution and wide color gamut into SDR-compatible formats by modifying the luminance mapping parameters, ensuring that the processed image can be displayed accurately on standard display devices while maintaining optimal visual quality.
Data Source
AI summary
In a method for processing an image, statistical information is obtained by performing histogram statistics on an image frame included in a video sequence. An overall compression ratio of the image frame and mid luminance information of the image frame are obtained based on the statistical information. A compression curve is obtained based on the overall compression ratio and the mid luminance information. Dynamic range compression is performed on the image frame by adjusting a shape of the compression curve based on the overall compression ratio, the mid luminance information and adjustment ratios.