Dynamic Range Expansion Using Luminance-Dependent Image Blending
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Many digital images have lower dynamic ranges than what can be displayed by high dynamic range displays or appreciated by the human eye, necessitating a method to enhance the dynamic range of image data.
Innovation Solution
A method and apparatus that apply an expansion function to original image data to generate expanded data with a higher dynamic range, combined with a luminance distribution analysis to create an expand map, which is used to combine the original and expanded data, effectively increasing the dynamic range of the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tone mapping operator is applied to reduce dynamic range of image data to match display characteristics, then the image data can be displayed on standard displays, but the visual fidelity and human perception accuracy are degraded
Solution Approach 1:
The patent applies local quality by using a luminance-dependent mask that varies across different regions of the image. The mask is generated based on luminance information, causing different portions of the image to be blended to different extents. In high-luminance regions, the original image is preserved more, while in low-luminance regions, the tone-mapped version is blended in more, optimizing both display compatibility and visual fidelity locally rather than applying a uniform transformation across the entire image.
2Manufacturing precision
If high dynamic range image data is acquired using high-performance image sensors, then accurate reproduction of real scenes is achieved, but standard displays cannot display such high dynamic range images
Solution Approach 1:
The patent applies dynamics by creating a dynamic blend between the original high dynamic range image and the tone-mapped version. The luminance-dependent mask dynamically determines the blending ratio for each pixel based on its luminance value, allowing the system to adaptively balance between preserving HDR quality and ensuring compatibility with standard displays. This dynamic approach enables the same image processing pipeline to serve both HDR and SDR display requirements.
3Adaptability or versatility
If dynamic range of image data is reduced to match display characteristics, then the image can be displayed on standard displays, but the dynamic range is insufficient for high dynamic range displays and human perception
Solution Approach 1:
The patent applies preliminary action by pre-processing the image data through tone mapping to create a version that is compatible with standard displays. This tone-mapped version is then blended with the original high dynamic range image using a luminance-dependent mask. The preliminary tone mapping ensures that the image can be displayed on standard displays, while the selective blending preserves high dynamic range characteristics in regions where the display capability allows, thus preparing the image for multiple display types.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for increasing dynamic range of original image data representing an image comprises applying an expansion function to generate from the original image data expanded data having a dynamic range greater than that of the original image data and, obtaining an expand map comprising data indicative of a degree of luminance of regions associated with pixels in the image. The method then combines the original image data and the expanded data according to the expand map to yield enhanced image data. Apparatus for boosting the dynamic range of image data comprises a dynamic range expander that produces expanded data, a luminance analyzer that produces an expand map and a combiner that combines the original and expanded data according to a variable weighting provided by the expand map.