yahvuu wrote: > That was thought as "color data that is defined in an absolute color space, > or can > be unambiguously transformed into such a color space". Perhaps a better term > is > 'unambiguous color data'.
Unfortunately, due to the adaptability of human vision, there is really no such thing as an absolute unambiguous color space. But for practical purposes there is something that everyone uses, and that is the CIE standard observer tri-stimulus space, XYZ. But note there are still many subtleties. The most popular XYZ spaces come in two flavours, 2 degree and 10 degree, referring to the viewing angle, since we have different type of color sensitive cells in the central and peripheral viewing regions of our eyes. For practical use, there is often the assumption that the viewer is perfectly adapted to the white point of the scene (ICC relative colorimetric), and XYZ is typically an absolute coordinate system, that doesn't normalise to any white point, hence the use of chromatic adaptation transforms. CIE XYZ assumes a set of standard viewing conditions (absolute brightness level, surround color etc.), whereas the real world probably has different viewing conditions, hence CIECAM02 etc. ICC device profiles codify a transformation from device colorspaces to/from PCS (Profile connection space), which is defined in terms of CIE XYZ. Psudo device independent spaces such as scRGB, sRGB, Adobe RGB are defined in terms of XYZ too. Note that there is some controversy of how to handle the white point adaptation to these spaces though, although this is only of relevance in specialised applications where absolute XYZ is required. Graeme Gill. _______________________________________________ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
