HDR Image Composition Using PQ Luminance and Variable Exposure Weights
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for generating composite high dynamic range (HDR) images fail to account for varying peak luminance due to different exposure amounts, leading to potential unnatural representations in high luminance regions when compositing HDR images encoded using the PQ method.
Innovation Solution
An image processing apparatus and method that adjusts composition percentages by linearizing and coordinating exposures of HDR images with different exposure amounts, applying a modified Mix table to ensure accurate luminance representation across the dynamic range, and generating a composite image with extended dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HDR images with different exposure amounts are composited using fixed composition percentages, then a composite image with extended dynamic range can be generated, but unnatural representations and color curving occur due to varying peak luminance values
Solution Approach 1:
The patent applies dynamics by making the composition percentages variable rather than fixed. The weighted addition coefficients are dynamically adjusted based on the peak luminance values of the input HDR images. Specifically, the composition percentage for each image is determined by the ratio of its peak luminance to the sum of peak luminances across all input images, allowing the system to adapt to different exposure conditions and prevent unnatural representations
Solution Approach 2:
The patent changes the parameter of composition percentages based on peak luminance values. By using peak luminance as a basis for determining weighted addition coefficients, the system transforms fixed composition ratios into variable parameters that reflect the actual luminance characteristics of each input image, thereby maintaining natural appearance across different exposure modes
2Measurement precision
If the PQ method is used to represent scene luminance in absolute terms, then accurate luminance representation is achieved, but peak luminance varies depending on exposure amount leading to composition problems
Solution Approach 1:
The patent applies preliminary action by calculating the peak luminance values of all input HDR images before performing the composition operation. This pre-calculation allows the system to determine appropriate weighted addition coefficients in advance, ensuring that images with different exposure amounts and peak luminances can be properly balanced in the final composite image
Solution Approach 2:
The patent uses feedback by utilizing the peak luminance values of input images to adjust the composition percentages. The system measures the peak luminance of each input HDR image and uses this information to determine the weighted addition coefficient, creating a feedback loop that ensures accurate luminance representation while maintaining adaptability across different exposure modes
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An image processing apparatus (100) that composites a plurality of images that have been captured with different exposure amounts, the image processing apparatus comprising: specification means for specifying a signal value indicating an upper limit value of an output dynamic range with respect to at least one of the plurality of images; and decision means (408) for deciding on composition percentages of the plurality of images based on the signal value specified by the specification means.