On Sun, Jun 6, 2010 at 10:51 PM, Elle Stone <l.elle.stone@xxxxxxxxx> wrote: > One of the issues Graeme mentions in “What’s wrong with the ICC > profile format anyway ?" is the fact that ICC v2 specifications > disallow negative tristimulus values. > > Recently I was comparing the gamut shape and size of several working > space profiles with the gamut of raw-rendered tiffs of highly > saturated flower images. I came to the same conclusion Ben Goren did > in the argyllcms archive > //www.freelists.org/post/argyllcms/Optimal-color-space-for-an-image,4, > that none of the spaces smaller than ProPhotoRGB were big enough to > hold even moderately saturated images. > > But really even ProPhoto isn't big enough for all images. The blue > channel of one particular flower image while still in camera space had > lots and lots of detail. After conversion to ProPhotoRGB, the details > in the blue channel had turned to a solid black blob. Once I started > looking, a lot of images turned out to have this problem of blue > channel detail going to black upon conversion to ProPhoto. I wrote up > my findings here: > http://www.dustystones.com/2010/photo-essays/intro/open-source-digital-imaging-intro.html > and here: > http://www.dustystones.com/2010/photo-essays/negative-primaries/negative-primaries.html. I'm noticing you're using AHD demosaicing, which is not really good for an EOS 400D (or Digital Rebel XT)... I have some samples about this at my old UFRaw FAQ: http://blog.pcode.nl/2009/08/23/ufraw-faq/ Recently Darktable has gotten green channel equilibration, so the mazing artifacts are resolved with any algorithm, however I seem to like VNG4 with a tad of unsharp mask better. Regards, Pascal de Bruijn