robert@xxxxxxxxxxxxxxxxxx wrote: > The second problem was that I was that I was using -pj in tiffgamut and -pl > in iccgamut, so I wasn't comparing apples to apples. With both set to -pj, > an sRGB image which isn't clipped is within the sRGB gamut viewed with > viewgam. Hi, yes, that is a trap. It would be nice to make the tools a bit more seamless in regard to that. > If -g is not used, the Perceptual mapping is from the gamut of the source > profile (which I will call SG) to the gamut of the destination profile > (which I'll call DG). The B2A0 table, which is responsible for the > Perceptual mapping, effectively 'squeezes' the whole of SG into DG. All of > the colors that were present in SG will be remapped to new colors in DG, > even if none of the colors in SG were outside of the DG gamut (the effect of > the 'squeeze'). > > The effect of using -g is to create a new gamut which is the union of DG and > CG (which I will call UG). No, effectively the Image Gamut (CG) becomes the Source Gamut (SG). [There are some subtleties - an image gamut isn't expected to contain the source colorspace white and black points, so the effective source gamut is the Image Gamut supplemented by some information from the Source Colorspace Gamut.] The gamut mapping creation is then basically the same. > - The table then does a Perceptual mapping from UG to DG. No, the table does a Perceptual mapping from the Image Gamut (CG) to Destination Colorspace Gamut (DG). Graeme Gill.