Comparing Displays Using Luma Contours and Color Volumes

摘要

COLORFULNESS INCREASES AS ABSOLUTE LUMINANCE increases (this is known as the Hunt effect); the same is true of visual contrast, or what we call contrastiness (the Stevens effect). Further, both colorfulness and contrastiness depend upon surround conditions (the Bartleson/Breneman effect). High dynamic range (HDR) has higher absolute luminance than standard dynamic range (SDR) or high definition (HD) so it can appear to be more colorful than SDR, even without an increase in physical color gamut. Such appearance effects are aspects of human vision that cannot be measured by instruments. Although classic colorim etry deals with measurable color stimuli and can be addressed objectively, appearance effects are much more subtle and cannot be addressed objectively. Color appearance models that address these effects are relatively recent and still in development. To better understand these methods, here we compare two widely applied colorspaces, Digital Cinema Initiatives DCI P3 and Recommendation (Rec.) BT.1886 from the International Telecommunication Union Radiocommunication Sector (ITU-R), which specifies the same primaries as BT.709 and standard red, green, and blue [sRGB]. To that end, we use color volume and luma contours based upon the recent ITU-R recommendations BT.2100 and BT.2124. More detailed discussions of the development of BT.2100 IC_TC_P and description of the BT.2124 ΔE_(ITP) color difference metric are available elsewhere.910