HDR Video Level Mapping for LDR Display Compatibility
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Solution Overview
Problem
Displaying High Dynamic Range (HDR) images on Low Dynamic Range (LDR) monitors results in clipped blacks and whites, making the image appear wholly dark due to the inability to accurately represent the wide dynamic range of HDR data.
Innovation Solution
A transmission device applies a predetermined level-mapping curve to HDR video data to convert it into a narrower range suitable for LDR displays, accompanied by auxiliary information for level conversion on the receiving end, allowing for appropriate display of HDR images on LDR monitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HDR video data is directly displayed on LDR monitors, then the full dynamic range information is preserved, but the image quality deteriorates with clipped blacks and whites and overall darkness
Solution Approach 1:
The patent applies parameter changes by transforming the luminance level range of video data from a wide HDR range (0-N%) to a narrower LDR range (0-P%) through level-mapping curves. This parameter transformation allows HDR content to be displayed on LDR monitors while maintaining image quality, resolving the contradiction between preserving dynamic range information and ensuring display compatibility.
2Reliability
If a level-mapping curve is applied to compress the dynamic range, then the image displays well on LDR monitors, but the complexity of the transmission system increases due to auxiliary information requirements
Solution Approach 1:
The patent uses auxiliary information as an intermediary element that mediates between the level-mapped video data and the receiver's level conversion process. This auxiliary information contains the level-mapping curve parameters needed to reverse the compression, enabling the receiver to restore the original dynamic range. This approach maintains display compatibility while managing system complexity through standardized information exchange.
3Adaptability or versatility
If the range of levels is compressed from 0-N% to 0-P%, then LDR display becomes feasible, but the luminance distribution shifts causing the image to appear wholly dark
Solution Approach 1:
The patent applies preliminary action by pre-calculating and embedding the level-mapping curve parameters in auxiliary information during the transmission phase. This allows the receiving end to perform accurate level conversion before display, compensating for the luminance shift caused by compression. The preliminary preparation of conversion parameters ensures that the image maintains proper brightness distribution despite the level range compression.
Data Source
AI summary
The present invention allows for display of an image generated from HDR video data on an LDR monitor in good condition. Applying a predetermined level-mapping curve to the input video data (HDR video data) in a first range of levels provides the video data for transmission (LDR video data) in a second range of levels narrower than the first range of levels. The video data for transmission is transmitted together with the auxiliary information used to convert the levels on the receiving end.