COLOR SPACE AND DECODER FOR VIDEO

摘要

Because we needed a new improved and very different color encoding space for being able to faithfully encode the presently emerging high dynamic range video for good quality rendering on emerging HDR displays such as the SIM2 display, the video encoder (300) with an input (308) to obtain a video from a video source (301) wherein pixel colors are encoded in an (XYZ) color encoding, the video encoder comprising an opto-electronic conversion unit (304) arranged to convert the luminances (Y) of the pixel colors into lumas (Y′) with a predetermined code allocation function (F), characterized in that the video encoder comprises a chromaticity determination unit (310), which is arranged to encode chromaticities (u″,v″) of pixel colors with lumas (Y′) below a predetermined threshold luma (E′) with a mathematical chromaticity definition which yields a maximum encodable saturation (S_bL) for a particular hue for pixel colors with a luma below the predetermined threshold luma (E′) which is lower than a maximum encodable saturation (S_bH) for the particular hue for a pixel color with a luma above the predetermined threshold luma (E′), and a constant maximum encodable saturation (S_bH) for pixels with colors of a particular hue and a luma equal to or larger than the predetermined threshold luma (E′).

主权项

1. A video encoder with an input to obtain a video from a video source wherein pixel colors are encoded in a standardized device independent linear color encoding, the video encoder comprising an opto-electronic conversion unit arranged to convert the luminances of the pixel colors into lumas with a predetermined code allocation function, characterized in that the video encoder comprises a chromaticity determination unit, which is arranged to encode chromaticities of pixel colors according to a mathematical chromaticity definition which yields for pixel colors with a particular hue and a luma a maximum encodable saturation (S_bL), wherein a maximum encodable saturation (S_bL) represents the highest possible saturation for any pixel color having a particular hue, wherein saturation is calculated according to a distance of the color in a chromaticity plane for the particular luma from a pre-specified white point according to the equationS=sqrt((u″−u″w)2+(v″−v″w)2), which chromaticity definition yields for pixel colors with a particular hue and a luma below a predetermined threshold a maximum encodable saturation which is lower than a maximum encodable saturation (S_bH) for that particular hue for a pixel having a luma above the predetermined threshold luma, and which yields for pixel colors with the particular hue and a luma equal to or above the predetermined threshold luma a constant maximum encodable saturation (S_bH), and wherein the maximum codeable saturation (S_bL) for colors with a particular hue and a luma below the threshold luma decreases as a monotonic function of the luma of the pixel color.