HDR Image Coding with Metadata Tone Mapping Compatibility
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Solution Overview
Problem
Existing systems fail to correctly process and display high dynamic range (HDR) data due to independent modules lacking image buffers and metadata transmission, leading to inadequate display effects.
Innovation Solution
A method involving a double-layer bitstream system that combines decoded images in two buffers, using metadata for tone mapping to achieve correct HDR display, and fallback to baseline images for compatibility with different systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If independent modules (decoding module, graphics processing module, display module) are used with only one image buffer, then device complexity is reduced and ease of operation is improved, but HDR data processing capability deteriorates and display effect quality worsens
Solution Approach 1:
The patent segments the image processing into two distinct buffers: a first buffer for SDR baseline images and a second buffer for HDR images. This segmentation allows each buffer to handle specific data types independently, enabling proper HDR processing while maintaining the simplicity of the independent module structure. The decoding module decodes baseline images to the first buffer and HDR images to the second buffer, preventing data mixing and ensuring reliable HDR processing.
Solution Approach 2:
The patent introduces metadata as an intermediary element that carries essential information between modules. The metadata includes transfer characteristics, color space information, and dynamic range parameters, enabling the graphics processing module and display module to correctly process and display HDR content. This intermediary data structure resolves the information loss problem in the independent module architecture.
2Device complexity
If metadata is not transmitted and only one image buffer is used, then device complexity is reduced, but image quality and HDR processing capability deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-processing HDR images into baseline images with embedded metadata before transmission and storage. The metadata is prepared in advance with all necessary transfer characteristics and color space information, so that when the image is decoded and displayed, the processing modules can immediately use this pre-prepared information without requiring complex real-time analysis, thus maintaining image quality while avoiding additional device complexity.
Solution Approach 2:
The patent utilizes parameter changes by encoding multiple sets of image data with different dynamic range parameters into the same bitstream. The baseline image uses SDR parameters while the HDR image uses HDR parameters, and metadata indicates which set to use. This allows a single buffer to effectively handle multiple parameter sets, improving image quality without requiring separate physical buffers for each parameter type.
3Manufacturing precision
If double-layer bitstream with two buffers is used, then HDR display quality is improved, but device complexity increases
Solution Approach 1:
The patent makes the image buffer universal by designing it to handle both SDR baseline images and HDR images through the double-layer bitstream approach. The same buffer infrastructure is used for both data types, with metadata guiding the appropriate processing path. This multi-functionality allows the system to achieve HDR display quality without proportionally increasing the buffer structure complexity, as the buffer serves dual purposes.
Solution Approach 2:
The patent applies dynamics by making the buffer allocation and processing path dynamic based on metadata indicators. The system can switch between processing baseline images and HDR images in the same buffer, with the processing behavior adapting dynamically according to the metadata. This dynamic approach allows HDR quality without requiring permanently dedicated separate buffers, thus limiting the increase in device complexity.
4Manufacturing precision
If upsampling or downsampling is performed based on metadata, then image quality is improved and adaptability is enhanced, but processing time increases
Solution Approach 1:
The patent applies preliminary action by performing upsampling or downsampling operations during the initial image encoding and metadata generation phase, rather than during real-time playback. The target resolution information is embedded in the metadata, allowing the image to be pre-processed to the appropriate resolution. This eliminates the need for time-consuming processing during display, thus improving image quality while minimizing processing time loss during actual use.
Data Source
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AI summary
A signal processing method provided in this application includes: obtaining a first baseline image, a first gain map, and metadata, where the first baseline image corresponds to a first dynamic range; processing the first baseline image based on the metadata to obtain a second baseline image; and obtaining a target image based on the second baseline image and the first gain map, where the target image corresponds to a second dynamic range, and the second dynamic range is different from the first dynamic range. The solutions provided in this application are compatible with image encoding and processing in a plurality of formats, and comparatively good image quality can be achieved on systems with different support capabilities.