Method of digital processing for digital cinema projection of tone scale and color

Abstract

A method for re-mapping out of gamut colors into a display device color space. The method includes determining a maximum color gamut of the display device in a perceptual color space that represents the combination of hue, lightness and saturation; and determining if a target color is out of gamut for the display device. Accordingly, an out of gamut target color is provided. One may then obtain a hue angle for the out of gamut target color. Using the hue angle, one determines the lightness value of the out of gamut target color. Subsequently, one would hold the one holding the hue angle constant, altering the lightness and saturation, as necessary to bring the out of gamut target color into the display device color space.

1 . A method for re-mapping out of gamut colors into a display device color space, said method comprising the steps of: 
 determining a maximum color gamut of the display device in a perceptual color space that represents the combination of hue, lightness and saturation;    determining if a target color is out of gamut for the display device, thereby providing an out of gamut target color;    obtaining a hue angle for the out of gamut target color;    using the hue angle, determining the lightness value of the out of gamut target color; and    holding the hue angle constant, altering the lightness and saturation, as necessary to bring the out of gamut target color into the display device color space.    
     
     
         2 . The method as claimed in  claim 1  wherein the perceptual color space is CIE LAB color space.  
     
     
         3 . The method as claimed in  claim 2  wherein the step of determining a maximum color gamut comprises the steps of setting a maximum saturation at each hue angle in CIE LAB space and calculating a lightness value at each of the hue angles.