Chromatic Calibration of HDR Displays Using Octree Forests
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Solution Overview
Problem
High Dynamic Range (HDR) displays introduce distortions in chromatic data reproduction, limiting the rendering of brightness levels and color accuracy due to limited dynamic range and gamut, necessitating efficient calibration methods for real-time correction.
Innovation Solution
The use of spatial data structures, such as octree forests, to efficiently represent and access calibration data, allowing for real-time chromatic calibration by approximating the deformation field with Thin-Plate Splines-based functions and adaptive sampling, minimizing color reproduction errors across varying luminance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full-resolution look-up table (LUT) is used to store calibration data for HDR displays, then color accuracy is improved, but memory size and access time increase significantly
Solution Approach 1:
The patent divides the continuous chromaticity space into discrete triangular regions formed by connecting measured primary color points. This segmentation transforms the problem from storing calibration data for every possible color value to storing only the vertex points of these triangles, dramatically reducing memory requirements while maintaining color accuracy through interpolation within each triangle.
Solution Approach 2:
The patent creates a simplified geometric model (triangular mesh) that copies the essential structure of the chromaticity space deformation. Instead of storing actual calibration measurements for all points, it stores a geometric representation that can generate calibrated values through interpolation, reducing memory from gigabytes to manageable sizes.
2Adaptability or versatility
If chromatic calibration is performed for HDR displays with limited dynamic range, then device compatibility is improved, but color fidelity and dynamic range reproduction deteriorate
Solution Approach 1:
The patent measures and records the actual primary color coordinates of the HDR display under test, which inherently capture the display's specific dynamic range and gamut characteristics. The calibration process then uses these measured parameters to compute corrected chromaticity values that compensate for the display's limitations, enabling accurate color reproduction within the display's actual capabilities rather than assuming ideal HDR performance.
3Productivity
If real-time calibration is implemented for HDR displays, then processing speed is improved, but computational complexity and memory access requirements increase
Solution Approach 1:
The patent performs the complex measurement and triangle mesh construction process during an initialization phase before real-time operation. During runtime, calibration reduces to simple geometric operations (determining which triangle contains the input chromaticity value and performing barycentric interpolation), which are computationally trivial and enable real-time processing without complex calculations.
Data Source
AI summary
Methods and systems for calibrating devices reproducing high dimensional data, such as calibrating High Dynamic Range (HDR) displays that reproduce chromatic data. Methods include mapping input data into calibrated data using calibration information retrieved from spatial data structures that encode a calibration function. The calibration function may be represented by any multidimensional scattered data interpolation methods such as Thin-Plate Splines. To efficiently represent and access the calibration information in runtime, the calibration function is recursively sampled based on guidance dataset. In an embodiment, an HDR display may be adaptively calibrated using a dynamic color guidance dataset and dynamic spatial data structures.