Spline Tone Mapping for HDR Luminance Detail Reproduction
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Solution Overview
Problem
Display devices struggle to accurately reproduce scenes from the real world due to limitations in their dynamic range, failing to display both very bright and very dark elements effectively.
Innovation Solution
An image processing method that modifies an initial tone mapping curve using spline functions based on interpolation points determined by luminance information and dynamic metadata, allowing for flexible adjustment of image display to enhance luminance details and improve visual experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If no processing is performed on high luminance scenes, then the original luminance values are preserved, but the display device cannot reproduce the scene due to limited maximum luminance
Solution Approach 1:
The patent applies parameter changes by modifying the tone mapping curve based on scene luminance characteristics. The curve is adjusted to map high luminance values from the captured scene to the display device's maximum luminance capability, preserving relative luminance relationships while adapting to the device's limited range. This allows accurate reproduction of high luminance scenes within the display device's capabilities.
2Manufacturing precision
If no processing is performed on low luminance scenes, then the original luminance values are preserved, but the display device cannot reproduce the scene due to minimum luminance limitations
Solution Approach 1:
The patent modifies the tone mapping curve to handle low luminance scenes by mapping the scene's minimum luminance values to the display device's minimum displayable luminance. This ensures that dark regions in the captured scene are visible on the display device while maintaining the relative luminance structure of the original scene.
3Ease of operation
If a fixed tone mapping curve is used, then the processing is simple, but the image display cannot be adjusted for different luminance regions
Solution Approach 1:
The patent implements dynamic tone mapping by adjusting the tone mapping curve based on the luminance characteristics of each scene. The system analyzes the captured image's luminance distribution and dynamically modifies the curve parameters to optimize display for that specific scene, rather than using a fixed curve for all situations.
Solution Approach 2:
The patent applies local quality by differentiating tone mapping processing for different luminance regions within the same image. The system identifies high luminance regions, low luminance regions, and mid-tone regions, and applies appropriate mapping adjustments to each region to preserve luminance details across the entire image.
4Manufacturing precision
If complex processing is applied to adjust tone mapping for different luminance regions, then luminance details are enhanced, but the calculation complexity increases
Solution Approach 1:
The patent segments the tone mapping process into distinct stages: luminance analysis, curve parameter determination, and regional adjustment application. By dividing the complex processing into manageable segments, the system can enhance luminance details through regional adjustments while keeping each processing stage computationally efficient.
Data Source
AI summary
An image processing method includes obtaining a target picture and an initial tone mapping curve of the target picture, determining a plurality of interpolation points based on luminance information and/or dynamic metadata of the target picture, and determining a spline function that passes through the plurality of interpolation points, where the spline function is smoothly connected to the initial tone mapping curve at at least one of the plurality of interpolation points the initial tone mapping curve is modified based on the spline function to obtain a modified tone mapping curve of the target picture; and tone mapping is performed on the target picture based on the modified tone mapping curve. This image processing apparatus enables a display device to vividly and realistically reproduce a scene in a real world.