Dynamic Range Transforming for HDR-LDR Display Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image processing systems struggle to efficiently convert between High Dynamic Range (HDR) and Low Dynamic Range (LDR) images while maintaining optimal image quality and compatibility with various display types, leading to suboptimal rendering on displays with different brightness levels.
Innovation Solution
An image processing apparatus and method that applies dynamic range transforms based on target display references, allowing adaptation to specific display characteristics, including white point luminance and Electro Optical Transfer Function, to convert between HDR and LDR images, while retaining artistic control and optimizing for individual display types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LDR encoding is used for HDR displays, then backwards compatibility is maintained, but quantization and clipping artifacts appear and image quality deteriorates
Solution Approach 1:
The image signal is segmented into multiple dynamic range versions (LDR and HDR) that are separately encoded and transmitted. This allows each version to be optimized for its specific display type, with the LDR version maintaining backwards compatibility and the HDR version providing superior image quality for HDR-capable displays.
Solution Approach 2:
The solution adds a new dimension to the encoding system by incorporating HDR capability alongside traditional LDR encoding. This dimensional expansion allows the system to serve both legacy and advanced displays simultaneously, transforming a single-dimension (LDR only) system into a multi-dimensional system that accommodates different display capabilities.
2Manufacturing precision
If separate encoding for HDR and LDR displays is implemented, then optimal image quality for each display type is achieved, but data rate and system complexity increase
Solution Approach 1:
The HDR image is generated as a preliminary version during the encoding process, and the LDR version is derived from it through tone mapping. This preliminary action approach allows both versions to be created in a single encoding pass, reducing the need for separate encoding processes and thereby lowering system complexity while maintaining optimal image quality for both display types.
3Loss of information
If HDR encoding is applied to LDR displays, then additional information is conveyed, but the information cannot be fully utilized and headroom is insufficient
Solution Approach 1:
The LDR display acts as an intermediary that receives and displays both LDR and HDR encoded content. The system includes mechanisms to detect display capabilities and automatically select or transform the appropriate version, allowing HDR-encoded content to be properly adapted for LDR displays through tone mapping and other transformation techniques.
Data Source
AI summary
An image processing apparatus comprises a receiver (201) for receiving an image signal which comprises at least an encoded image and a target display reference. The target display reference is indicative of a dynamic range of a target display for which the encoded image is encoded. A dynamic range processor (203) generates an output image by applying a dynamic range transform to the encoded image in response to the target display reference. An output (205) then outputs an output image signal comprising the output image, e.g. to a suitable display. The dynamic range transform may furthermore be performed in response to a display dynamic range indication received from a display. The invention may be used to generate an improved High Dynamic Range (HDR) image from e.g. a Low Dynamic Range (LDR) image, or vice versa.