Color mapping method

Abstract

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 (Lambada 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 (Lambada 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 pixelcolors 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) isdefined by the mapped chromaticity (xm, ym) and the output luminance (Ys).

Description

technical field [0001] The invention relates to a method of designing a display, a method of manufacturing a display, a display and a computer program product. Background technique [0002] In order to display color images, conventional displays have three primary colors: red, green and blue. In Europe, the chromaticity coordinates of these primary colors are defined by the EBU standard for standard definition content and the Rec709 standard for high definition content. Chromaticity coordinates are also known as color points or colors. In other countries, different standards may define the colors of the three primary colors. In the EBU standard, the chromaticity coordinates of the red primary color in the CIE 1931 xy color space are: x=0.64 and y=0.33, the green primary color is: x=0.29 and y=0.60, and the blue primary color is: x=0.15 and y= 0.06. The white point of a display is also defined in the EBU standard, which is close to D65 (6500K) with chromaticity coordinate...

AI Technical Summary

Problems solved by technology

[0006] Similarly, if EBU content must be displayed on a display with primaries providing a gamut smaller than the EBU gamut, or if wide-gamut content must be displayed on a display with an EBU gamut, the colormap must scale the input gamut down to a smaller display gamut, and again color reproduction suffers

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