HDR to SDR Luminance Conversion via Peak Brightness Mapping
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Solution Overview
Problem
Existing image signal processing apparatuses fail to effectively convert luminance from a high dynamic range (HDR) to a standard dynamic range (SDR) for display on SDR TVs, limiting the ability to showcase HDR content on non-HDR enabled devices without significant upgrades.
Innovation Solution
A method and apparatus for converting HDR signals to pseudo HDR signals, allowing SDR TVs to display content with a luminance range similar to HDR, by utilizing HDR EOTF converters, luminance converters, and inverse SDR EOTF converters to adapt HDR content to the display capabilities of SDR TVs, thereby enabling higher luminance representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If HDR content is displayed on SDR TVs using conventional conversion methods, then the luminance range is limited to standard dynamic range, but the HDR quality and luminance representation are degraded
Solution Approach 1:
The patent applies parameter changes by modifying the luminance values through multiple conversion stages: first converting HDR luminance to display luminance using display peak luminance, then converting display luminance to SDR luminance using SDR peak luminance. This two-stage parameter transformation enables SDR TVs to display HDR content with enhanced luminance representation while maintaining conversion accuracy through systematic parameter adjustment.
2Adaptability or versatility
If HDR EOTF conversion is performed to convert code values to luminance values, then the luminance range is expanded, but the conversion complexity increases
Solution Approach 1:
The patent segments the conversion process into distinct stages: HDR EOTF conversion, luminance conversion using display peak luminance, and SDR EOTF conversion. By dividing the complex conversion task into manageable segments with clear intermediate steps, the system achieves comprehensive luminance range adaptability while keeping each conversion stage's complexity controlled and manageable.
Solution Approach 2:
The patent performs preliminary actions by pre-determining the display peak luminance and SDR peak luminance values, and pre-establishing the conversion relationships between different luminance ranges. This preliminary preparation enables the conversion system to handle various HDR content with different luminance characteristics without requiring complex real-time calculations, thus reducing overall conversion complexity.
3Device complexity
If conventional luminance conversion is used without considering display peak luminance, then the conversion process is simplified, but the luminance representation accuracy is reduced
Solution Approach 1:
The patent introduces display peak luminance as an intermediary parameter that mediates between HDR luminance and SDR luminance conversion. By using this intermediary reference point, the conversion process maintains simplicity through a clear two-stage process while achieving high luminance representation accuracy. The intermediary parameter enables precise mapping of luminance values across different dynamic ranges without requiring complex conversion algorithms.
Data Source
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AI summary
A conversion method for converting luminance of a video, including a luminance value in a first luminance range, to be displayed on a display apparatus includes: acquiring a first luminance signal indicating a code value obtained by quantization of the luminance value of the video; and converting the code value indicated by the acquired first luminance signal into a second luminance value determined based on a luminance range of the display apparatus, the second luminance value being compatible with a second luminance range with a maximum value smaller than a maximum value of the first luminance range and larger than 100 nit. This provides the conversion method capable of achieving further improvement.