For reasons that don't fit in the margins of this entry, I've been looking at and doing brief tests with a bunch of Linux RAW processing programs lately. Rather than have all of this fall out of my mind in a bit, here's my views written down.

(If you're coming here through a web search you should pay attention to the publication date of this entry. The information here will probably be out of date in six months and will definitely be out of date in a year or two. I'll put in a link to any future updates I make.)

Update (April 16 2013): I now recommend darktable over Rawtherapee. See DarktableVsRawtherapee.

As a starting point I will note that I do not want a program to do catalog management for me. I have my own system for that and I've got no interest in shoveling all of my photographs into some opaque black box. What I want out of a RAW processing program is processing a directory of RAW files and generating output; I will take it from there, thanks.

• Bibble 5: Apart from not being buyable any more, not having been updated for any cameras released since mid to late 2011, and a certain paucity of plugins, this works great. It's what I use now and will be using for as long as possible (ie, until I get a new camera that it doesn't support). Yes, it costs money; it was worth it (on Linux).

• AfterShot Pro: This is what Bibble 5 was upgraded into after Corel bought out Bibble Labs. It may work well for some people but for me it was strictly worse than Bibble 5 (except for some plugins). The straw that broke the camel's back was realizing that its handling of white balance was so broken that I couldn't change white balance or use spot white balance at all (if I did, it added bonus colour casts and white wasn't). This bug was known and had not been fixed across multiple updates and releases.

  (If ASP did not have this bug I would probably be using it today as my best option. But the other problem with ASP is that there is a great deal of uncertainty over whether Corel will keep updating it to, for example, add support for new cameras. That they fired the entire Bibble development team is broadly not seen as good news.)

• Rawtherapee: Tolerable (assuming that you're using the latest source code or 4.0.10; 4.0.9 mangled colours in some of my D90 NEFs). I have various gripes with RT and it's often rather clunky and nowhere near as fluid as Bibble, but it ultimately does work. I could use it, although I would grit my teeth periodically. Rawtherapee is your best current option on Linux even though it doesn't fill me with enthusiasm.

  (One problem is that RT offers you too many options for doing things and no guidance on which one is usually the best approach. I feel fairly strongly that RAW processors should pick one best option for as many things as possible and then put it front and center, relegating any other versions to the distant sidelines.)

• darktable is my dark horse hope. I'd like to love it but I just can't in the end because every time I use it I'm left with very divided opinions. On the one hand, there's a bunch of stuff that it gets right (and better than Rawtherapee). On the other hand there's also a lot of things that I feel it gets wrong and some things that are plain out in utter left field. It's also even more complex and scattershot than Rawtherapee, which makes for a very frustrating experience; at one point I almost gave up on it over my inability to find basic adjustments for saturation.

  (It turns out that in the darktable way there are several different saturation adjustments; one in 'Velvia', one hiding inconspicuously in the colour correction module, and one in 'Vibrance'. I had to Google this to find a blog entry from the darktable people. RAW processors should have a prominent panel of standard image options like brightness, saturation, contrast, etc, all using the best version that the processor has.)

  Although I'm sure that it's an illusion, darktable really feels to me like no actual photographer tried to use it for serious work (even more so than Rawtherapee, which has some of the same issues). It has so many usability issues and things that I think should be different that it feels more like a project by enthusiastic programmers who shoved as many nifty image processing tools into it as they could without sitting down to process photographs and then ask themselves 'does this actually work in practice?'.

  I can imagine using darktable and in some ways I feel that it's better than Rawtherapee but I don't think I'd really enjoy it in the state that darktable is in today. Also, every so often in my testing I ran into UI glitches and bugs. One way to put this is darktable is a program that you love despite itself.

  PS: the best way to make darktable just process a directory of files instead of trying to import everything into a collection is 'darktable --library :memory: /your/dir'. (Thanks go to <hanatos> on the darktable IRC channel.)

• Lightzone is the great white hope of Linux RAW processors, a commercial RAW processor that failed in the marketplace but was then released as open source (see the Wikipedia entry). Unfortunately there are no actual opensource builds yet. But lots of people quite liked the commercial version, so maybe someday.

• rawstudio is either too basic or too good at hiding its more advanced options. I stopped looking at it after I couldn't find an option for spot white balance.

• fotoxx: I found the version of this packaged by Fedora 17 to be clumsy, awkward, annoying, and limited. I think its interface is a terrible mistake for getting real photo processing work done and I dislike its habit of silently writing out .tiff files for any RAWs that it appears to look at. I consider it unusable in practice.

• digiKam: I don't want a 'photo management application' that insists on swallowing all of my photos. I just want to develop my RAWs. In the interests of fairness I gave it a basic try and it immediately failed the 'has spot white balance' test, which is not surprising when they basically steer you very hard away from actually processing your RAWs when you import them.

• Photivo: Not evaluated.
  The Fedora 17 package that they supply failed to run due to a missing file that should have been included. But the documentation on their web site doesn't make me encouraged about the program's likely features and power.

  Update, April 16 2013: I built Photivo from source and it turns out that it's purely for processing a single file at a time. This makes it useless for me regardless of any other merits it might have.

• UFRaw offers no viable way of going through a directory of RAWs to select which ones are worth working on; it's strictly oriented to processing a single one. This fails my usability criteria regardless of any actual RAW processing features it may have.

While this is every current Linux RAW processor that I know about, I probably don't know about them all. Please feel free to mention any that I've missed in the comments.

(Explicitly not considered: using Wine or some other Windows virtualization method to run various Windows software options.)

Sidebar: Macs and Windows are better for this

I'm going to say it straight up: the overall quality of the RAW processing software you can get on Macs and Windows clearly exceeds any of these Linux options. The closest that Linux can come is AfterShot Pro, and that is somewhere around third tier software in the Mac and Windows worlds. If good, high quality photo processing is a significant priority for you, you should not be doing it on Linux.

(My vague impression is that Macs are currently a somewhat better choice than Windows for reasons that do not fit in the margins of this sidebar.)

I don't process my photos on Linux because it's a good idea; I do it because I'm welded to Linux for other reasons and I'm not yet at the point where I'm willing to buy a second system (it'd be a Mac) and find the space for it. If I was more committed to my photography, this would be one of the things that would change.