Why introduce another camera profile format instead of using ICC camera profiles?
Some technical background is required to fully appreciate the reasons. First, ICC camera profiles used by raw converters today are designed to process output-referred (i.e., rendered) image data, not scene-referred (i.e., raw) image data. Furthermore, the sequence and placement of color transformations described in an ICC camera profile can prevent other image processing stages (such as highlight recovery algorithms) from performing optimally. Third, there is no standard that describes the input color space of the ICC camera profile color transformation (it is often, but not always, a tone-mapped set of RGB camera coordinates). Consequently, ICC camera profiles are not portable: they can only be used with the raw converter for which they were explicitly created in the first place. Using an ICC camera profile designed for one raw converter with another raw converter nearly always produces incorrect (though sometimes entertaining) results. In contrast, DNG camera profiles are designed sp
