Rational Optical-Electro Transfer Function for HDR Quantization
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Solution Overview
Problem
Conventional methods for processing high dynamic range (HDR) images result in stripe noise that is perceivable by the human eye, failing to meet quality requirements due to inadequate quantization quality, especially at low brightness values.
Innovation Solution
An optical-electro transfer function is proposed, which processes brightness information using a rational quantization function to improve quantization quality, allowing the HDR image to reach up to 10000 nits while maintaining a Weber score within the Schreiber threshold, thereby reducing stripe noise and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical-electro transfer function is used, then processing simplicity is maintained, but quantization quality deteriorates and stripe noise appears when brightness is less than 0.1 nits
Solution Approach 1:
The patent applies parameter changes by modifying the optical-electro transfer function from conventional forms to a rational function form: L' = (a*L + b)/(m*L + p). By adjusting parameters a, b, m, and p, the function optimizes the mapping relationship between input and output brightness values, ensuring Weber scores remain below the Schreiber threshold across the full brightness range including low brightness regions below 0.1 nits, thereby eliminating stripe noise while maintaining processing efficiency.
2Illumination intensity
If brightness range is expanded to 10000 nits, then dynamic range coverage is improved, but quantization precision deteriorates without the new transfer function
Solution Approach 1:
The patent uses parameter changes to achieve both expanded brightness range and maintained quantization precision. The rational transfer function with optimized parameters a, b, m, and p creates a non-linear mapping that provides finer quantization steps at low brightness values (below 0.1 nits) while still accommodating high brightness values up to 10000 nits. This parameter optimization ensures Weber scores remain below the Schreiber threshold across the entire extended dynamic range.
3Manufacturing precision
If rational quantization function is implemented, then quantization quality and dynamic range are improved, but computational complexity increases
Solution Approach 1:
The patent resolves the complexity issue by using a rational function form (a*L + b)/(m*L + p) rather than more complex non-linear functions. This form maintains relative computational simplicity while achieving superior quantization quality. The function requires only basic arithmetic operations (multiplication, addition, division) and can be pre-computed or cached, making it suitable for real-time HDR processing without significant increases in computational burden.
Data Source
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AI summary
Embodiments of the present invention disclose a method and an apparatus for processing a high dynamic range image, and a terminal device. The method includes: obtaining brightness information of an image; processing the brightness information, to obtain processed image information; quantizing the processed image information, to obtain quantized image information; and encoding the quantized image information, to obtain encoded image information. When the embodiments of the present invention are used, quantization quality is improved.