f-spot doesn't support color profiles (yet) and no one is actively working on this right now, but it's definitely something we're looking for.
regards s On Mon, 2007-10-29 at 20:53 +0100, Christoph Moench-Tegeder wrote: > Hi, > > Is there any ongoing work for supporting color profiles in f-spot? > I'm aware there's some code in src/Imaging/, but I already learned > it does "not enough". > Things I'd like to see: > - support for embedded color (ICC) profiles as per JFIF or Exif 2.2 > and for files using AdobeRGB as per Exif 2.21/DCF 2.0 when viewing > files. > - conversion from the profiles named above to sRGB when exporting > (optional, so you can use sRGB for web galleries, photo sharing > sites etc and the native color space of the file whenever needed). > > This obviously does not result in a "color managed workflow" but > will help dealing with color profiled images. > > I'm willing to help coding and testing, but I did not want to > duplicate work already done. Can someone of the developers > tell me which parts of the color profile code is working? > > Below I have compiled some points about color profiles and > file formats, in random order, for those who didn't already > dive into the gory details (sorry, it's a little lengthy): > - Do not expect to get a "color managed workflow" and such by > just having those profile thingies around. > - The two most important color spaces today are sRGB and AdobeRGB. > The former was supposed to be a "good guess" for most monitors > (roughly speaking) when it was designed, the latter was designed > by Adobe as enhanced "working color space" for preprint stages. > It has a somewhat better color reproduction in cyan and green > areas. > - A lot of software does not handle color profiles, but just > assumes sRGB on all images. This includes all major web browsers > except Apple Safari (and perhaps the upcoming Firefox 3) > and even a lot of image viewers (gqview-devel 2.1.5 does > support embedded profiles, but not Exif 2.21 as explained below; > additionally, gqview development seems dormant). Gimp 2.4 > supports color profiles, but not Exif 2.21. > For this reason images to be posted on the web should be in > sRGB color space. > - If files recorded in AdobeRGB are viewed as sRGB files (without > conversion), colors look very dull and grey. > - Strictly speaking, there is no such thing as a "JPEG file". > Today, whe have JFIF (JPEG File Interchange Format) and > Exif (Exchangeable Image File Format). The former does always > and the latter does often carry their "payload" (the image) > as JPEG compressed data. According to the papers, they require > slightly different metadata handling (almost(?) every application > does handle both file types just fine transparently to the user). > - if a (newer than 2003) camera records in AdobeRGB, it will > hopefully do so in compliance with Exif 2.21/DCF 2.0. Exif 2.21 > is an update to the widely known and used Exif 2.2 standard. > The most important part of the update (at least for this case) > is the support for color spaces besides sRGB and "uncalibrated". > So, if the Exif version of an photo file is 2.21 (0x0221 in tag > 0x9000 ExifVersion in APP1), it may have an color space of > "uncalibrated" (0xFFFF in tag 0xA001 ColorSpace in APP1 (Exif)) > and the string "R03" in Exif.Iop.InteropIndex (that's tag 0x001 > in the APP1 section), which marks it as a "DCF option file" with > AdobeRGB color space. An sRGB file has 0x0001 in ColorSpace and > "R98" in InteroperabilityIndex) and is called a "DCF normal > file". Also, a "DCF option file" is supposed to have an underscore > as the first character of it's file name (for example "_mg_1234.jpg" > when using Canon gear). > The string "R03" is not defined in Exif 2.2 but only in Exif 2.21. > - Some software indicated the use of AdobeRGB on Exif 2.2 files by > putting 0x0002 into Exif.Photo.ColorSpace. This is not covered by > the standard, and (hopefully) not to common. > The "right way" to indicate color profiles besides sRGB in Exif 2.2 > is to set Exif.Photo.ColorSpace to "uncalibrated" and supply the > profile in Exif.Photo.ICC_Profile (the profile itself is stored in > an APP2 section). > - Files created by other software (Gimp, Photoshop) will be in JFIF > format can carry an embedded profile in an APP2 section, but there > are no "real Exif tags". > - For correctly interpreting "DCF option files" with AdobeRGB color > space one needs to have the AdobeRGB profile around. You can download > these at http://www.adobe.com/digitalimag/adobergb.html but I think > their license is too tight for including the profile in open source > software. Alternatives are using a homebrewed profile "compatible > with Adobe RGB (1998)" (I think I've seen one in src/Imaging/Tiff.cs) > or instructing the user to download a profile on his own. There > have been suggestions from the OpenICC project to put color > profiles in /usr/share/color/icc/, /usr/local/share/color/icc/ or > ~/.color/icc/. > - Some reading: > the exiftool documentation http://www.sno.phy.queensu.ca/~phil/exiftool/ > the Exif 2.2 standard http://www.exif.org/specifications.html > a tutorial on color management basics > http://www.cambridgeincolour.com/tutorials/color-management1.htm > the most comprehensive freely available official source on > Exif 2.21/DCF 2.0 (no joking here) > http://www.cipa.jp/exifprint/contents_e/01exif2_2_e.html > > Regards > Christoph > _______________________________________________ F-spot-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/f-spot-list
