Dynamic Range Conversion Model for HDR Image Signal Processing
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Solution Overview
Problem
Current image processing technologies face challenges in effectively converting images between different dynamic ranges, leading to suboptimal display quality on various devices.
Innovation Solution
A method and apparatus for processing image signal conversion using a dynamic range conversion model (L′=F(L)=a×(p×Ln(k1×p-k2)×Ln+k3)m+b) to improve the quality of conversion between images in different dynamic ranges, adapting to display devices for better visual output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear quantization is directly performed on HDR video, then the encoding process is simple, but information about the HDR source is severely damaged
Solution Approach 1:
The patent applies non-linear transfer functions (optical-electro transfer function OETF and electro-optical transfer function EOTF) to transform the HDR video signal parameters before quantization. This changes the luminance distribution characteristics, allowing key luminance segments to be protected while enabling effective quantization to integral bit data for encoding.
2Loss of information
If a transfer function is used for non-linear transfer, then HDR luminance segments are protected, but the conversion process becomes more complex
Solution Approach 1:
The patent performs preliminary non-linear transfer using OETF before quantization and encoding. This preliminary action protects key HDR luminance segments by transforming them into a range suitable for subsequent processing, ensuring that important visual information is preserved before the signal undergoes quantization and compression.
Solution Approach 2:
The patent employs a dual transfer function approach with OETF for encoding and EOTF for decoding. The EOTF acts as an inverse transformation that restores the HDR luminance characteristics after quantization, providing a feedback mechanism that maintains image quality throughout the encoding-decoding cycle.
3Ease of operation
If conventional optical-electro transfer function is used, then the processing is straightforward, but the adaptation to different display devices is limited
Solution Approach 1:
The patent introduces dynamic parameters into the transfer function, including maximum luminance value (max_display_mastering_luminance) and minimum luminance value (min_display_mastering_luminance) of the display device. These parameters allow the transfer function to dynamically adapt to different display capabilities, enabling the same encoding process to work effectively across diverse display devices with varying luminance ranges.
Data Source
AI summary
Embodiments of this application provide a method for processing image signal conversion, including: obtaining a primary color component of a to-be-processed pixel; and converting a first value of the primary color component into a second value based on a preset dynamic range conversion model, where the dynamic range conversion model is:L′=F(L)=a×(p×Ln(k1×p-k2)×Ln+k3)m+b,whereL is the first value, L′ is the second value, and k1, k2, k3, a, b, m, n, and p are model parameters.