Color Mapping Method for Display Gamut Adaptation
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Solution Overview
Problem
Conventional displays with EBU primaries cannot reproduce all visible colors, leading to suboptimal color reproduction when displaying content with different gamuts, as they either distort saturated colors or make them appear fluorescent or dull.
Innovation Solution
A color mapping method that adjusts the luminance of display pixels by using a look-up table or mathematical models to match the desired luminance of real-world objects, ensuring accurate color representation by interpolating relative luminances within the display's gamut, thereby avoiding artifacts like fluorescence or dullness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wide gamut primaries are used to expand the display color gamut, then the display can reproduce more saturated colors, but the luminance of displayed colors becomes uncontrolled and causes artifacts like fluorescence or dullness
Solution Approach 1:
The invention changes the luminance parameter of displayed colors by applying a correction factor derived from reflective spectra luminances. This adjusts the displayed luminance to match natural object luminances, resolving the uncontrolled luminance issue while maintaining the expanded color gamut benefits
Solution Approach 2:
The invention uses lookup tables or mathematical models that store desired luminance values for different chromaticities. This feedback mechanism compares displayed luminance with desired luminance and applies corrections to achieve accurate color reproduction across the wide gamut
2Reliability
If conventional EBU primaries are used to maintain compatibility with standard content, then the display can reproduce standard colors accurately, but it cannot reproduce highly saturated monochromatic colors
Solution Approach 1:
The invention dynamically adjusts the display behavior based on the input signal characteristics. By detecting whether colors fall within or outside the EBU gamut and applying appropriate luminance corrections, it maintains compatibility with standard content while enabling accurate reproduction of saturated colors when displayed on wide gamut displays
Data Source
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AI summary
A color mapping method maps an input image signal (IS) into an output image signal (OS) for a display (DD) with display pixels (Pi) having sub-pixels (RP, GP, BP, YP) with primary colors (RW, GW, BW, YW) defining a display color gamut (WG). A look-up table (1) comprises stored luminances (LU) of reflective spectra (RS) at different chromaticities (?O) within the display color gamut (WG). The reflective spectra (RS) are spectra of reflective objects (RO) having a substantial maximum reflectivity at the corresponding chromaticities (?O). The color mapping method comprises a gamut mapping (2), retrieving (3) a looked-up luminance (Yl), a factor determination (4), and adapting the mapped luminance (Ym; Y). The gamut mapping (2) maps the input image signal (IS) having input pixel colors defined by an input luminance (Y) and an input chromaticity (x, y) into a mapped image signal (MS) having corresponding mapped pixel colors defined by a mapped luminance (Ym; Y) and a mapped chromaticity (xm, ym). The input pixel colors lie within an input color gamut different than the display color gamut (WG). The looked-up luminance (Yl) is retrieved (3) by looking up the stored luminance (LU) in the look-up table (1) at the mapped chromaticity (xm, ym). The factor (F) is determined (4) from a difference between the looked-up luminance (Yl) and the mapped luminance (Ym; Y). The mapped luminance (Ym; Y) is adapted (5) by using the factor (F; G) to obtain an output luminance (Ys) nearer to the looked-up luminance (Yl) than the mapped luminance (Ym). The image output signal (OS) is defined by the mapped chromaticity (xm, ym) and the output luminance (Ys).