Luminance-Qualified Chromaticity Mapping for Color Grading
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Solution Overview
Problem
Existing systems for evaluating color distribution in images and video do not consider luminance levels, as pixels with the same chromaticity values but different luminance levels map to the same location in chromaticity charts, preventing accurate luminance-based color evaluation.
Innovation Solution
A system that generates luminance-qualified chromaticity representations by filtering pixels based on specified luminance ranges and mapping only those within the desired range to a CIE chromaticity diagram, allowing for luminance-gated images and corresponding chromaticity gamut diagrams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional chromaticity diagrams are used to evaluate color distribution, then chromaticity values can be visualized, but luminance information is lost because pixels with different luminance levels map to the same location
Solution Approach 1:
The patent segments the chromaticity diagram by creating multiple stacked layers, each representing a specific luminance range. This segmentation allows luminance information to be preserved while maintaining the chromaticity visualization, as each layer captures chromaticity data for a distinct luminance band without overlapping with other layers.
Solution Approach 2:
The patent adds a third dimension (luminance) to the traditional two-dimensional chromaticity diagram by stacking multiple layers vertically. Each layer corresponds to a different luminance range, transforming the flat 2D chromaticity space into a 3D luminance-qualified chromaticity space that preserves both chromaticity and luminance information.
2Measurement precision
If all pixels are included in chromaticity analysis, then complete color distribution is captured, but luminance-based evaluation is impossible due to overlapping pixels from different luminance levels
Solution Approach 1:
The patent extracts pixels within specific luminance ranges from the complete image and places them into separate luminance-qualified layers. This extraction allows for precise luminance-based color evaluation within each layer while maintaining the ability to analyze complete color distribution across all layers collectively.
Solution Approach 2:
The patent applies local quality by allowing different luminance ranges to be analyzed with different characteristics in different layers. Each layer can be independently evaluated for its specific luminance zone, enabling precise local luminance-based color evaluation while the collection of all layers preserves complete color distribution information.
3Measurement precision
If luminance filtering is applied to isolate specific luminance zones, then accurate luminance-based evaluation is achieved, but the overall color distribution view is reduced
Solution Approach 1:
The patent creates a dynamic system where users can selectively view individual luminance-qualified layers or combine multiple layers as needed. This dynamic approach allows accurate luminance-based evaluation of specific zones when viewing individual layers, while the ability to combine layers restores the complete color distribution view when needed.
Solution Approach 2:
The patent structures the chromaticity analysis as nested layers, where each luminance-qualified layer is contained within the overall multi-layer structure. This nesting allows detailed analysis of specific luminance zones within individual layers while maintaining the complete color distribution context through the nested hierarchy of all layers combined.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
A test and measurement device is described that has an input for receiving a selected image, a display output, and one or more processors configured to receive a maximum and minimum luminance value related to the selected image, and generate a chromaticity diagram of the image on the display output for only those pixels in the selected image that have luminance values between the maximum and minimum luminance values. The device may also generate a modified image from the selected image in which pixels from the selected image that fall within the maximum and minimum luminance value are reproduced in the modified image without modification and other pixels not within the maximum and minimum luminance value are modified. Methods are also described.