PQ to HLG HDR Signal Conversion with Luminance Parameter Mapping
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Solution Overview
Problem
When converting a Perceptual Quantization (PQ) High Dynamic Range (HDR) signal to a Hybrid Log Gamma (HLG) HDR signal, existing methods do not provide a clear approach for handling associated parameters, particularly the maximum luminance value, leading to incompatibility and incorrect processing.
Innovation Solution
An image processing apparatus and method that acquire a PQ image with its associated maximum luminance information, convert this information in a manner consistent with the conversion of the image from PQ to HLG, and associate it with the converted HLG image, ensuring compatibility and accurate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a PQ HDR signal is converted to an HLG HDR signal using existing methods, then the image conversion is completed, but the associated parameters (such as maximum luminance value) become incompatible and cannot be correctly applied to the converted signal
Solution Approach 1:
The patent applies parameter changes by converting the maximum luminance value parameter from the PQ signal's absolute luminance scale to the HLG signal's relative luminance scale. The conversion unit transforms the maxDRL parameter through the same transfer function that converts the image signal, ensuring the parameter remains accurate and applicable after format conversion.
Solution Approach 2:
The patent uses the transfer function as an intermediary to bridge the PQ and HLG parameter systems. By applying the transfer function to both the image signal and the associated maximum luminance parameter, it creates a consistent transformation that maintains parameter validity across different signal formats.
2Ease of operation
If the maximum luminance value parameter from a PQ signal is directly used for the converted HLG signal, then processing is simplified, but the luminance mapping becomes incorrect due to different luminance treatment approaches
Solution Approach 1:
The patent transforms the maximum luminance parameter through the transfer function to adapt it from PQ's absolute luminance scale to HLG's relative luminance scale. This parameter change ensures that the converted parameter accurately reflects the luminance characteristics of the HLG signal while maintaining a straightforward conversion process.
3Reliability
If different transfer functions are used for PQ and HLG standards, then each standard maintains its luminance characteristics, but converting associated parameters between standards becomes complex and error-prone
Solution Approach 1:
The patent makes the transfer function universal by using it for both image signal conversion and parameter conversion. The same transfer function that converts PQ image data to HLG image data also converts the associated maximum luminance parameter, eliminating the need for separate conversion logic and reducing overall system complexity.
Data Source
AI summary
An image processing apparatus that handles a High Dynamic Range (HDR) signal is disclosed. The apparatus acquires a Perceptual Quantization (PQ) image comprised of a HDR signal conforming to Perceptual Quantization (PQ), and information relating to a maximum luminance value of the PQ image, which is associated with the PQ image. The apparatus converts the PQ image into a Hybrid Log Gamma (HLG) image comprised of an HDR signal conforming to Hybrid Log Gamma (HLG); converts the information relating to the maximum luminance value in the same manner as in the conversion of the PQ image to the HLG image; and associates the HLG image with the converted information relating to the maximum luminance value.