I have been taking photographs with RAW format.
What tools are available for working with RAW under Linux?
Darktable is starting to look quite impressive http://www.darktable.org/
Raw Therapee is getting to be quite nice, and was recently made open source. I've had success with building it myself, or just using the precompiled Windows version under WINE (with a bit of a slow down, but not bad).
Raw Therapee is making its way into most popular distributions and can be installed via the system package manager. Be sure to check for it prior to installing the source build, unless of course you want the latest / bleeding edge build.
Bibble Pro is a cross-platform program similar to Lightroom and Aperture. Great program, great plugins, great performance.
As of early 2012, the product is discontinued, as the entire company was bought by Corel. Corel has announced a new program, AfterShot Pro, which is "based on Bibble's technologies", and which is also available for Linux, Mac, and Windows.
I use digikam - it supports 300 RAW formats. You can see previews in the organise mode and edit RAW photos with the built in editor. The editor supports 16 bit colour depth and has enough features to support most amateurs.
I think Raw Therapee might be a little better technically as a stand alone editor, but if you're not a pixel peeker then digikam makes life pretty easy by supporting all the photo management needs in one place.
Geeqie is a great viewer of RAW (and all other) file types.
It can thumb through your images at lightning speed, allowing you to delete the blurry ones quickly. While many RAW viewers take 2 to 5 seconds to display each RAW image, Geeqie is basically instant (probably around 0.15 seconds). Another neat feature of Geeqie is you can set it to retain the same zoom level and position as you go forward and back (PgDn/PgUp) through the images, which is great for checking focus of a bunch of shots of the same thing.
The reason it's so fast is that for RAW files, it displays the embedded JPEG instead of developing the RAW data. All RAW files from a camera contain a high-resolution embedded JPEG which is what allows your camera to display and zoom into the image on its LCD while it's in play mode. Geeqie is basically doing the same.
Of course you need separate software for actually editing/processing of RAW files, and I use Rawtherapee for that as I think it's the best quality available, but it's necessary to have a fast viewer, and fast is NOT Rawtherapee.
I recently came across Rawstudio which seems to be very good for the task of going through RAW files. It is focused on processing the RAW images, so it doesn't do image manipulation beyond conversion, or general management of images, but does seem to have a very usable workflow for the conversion process.
Photivo is a free and open source (GPL3) photo processor. It handles your RAW files as well as your bitmap files (TIFF, JPEG, BMP, PNG and many more) in a non-destructive 16 bit processing pipe with gimp workflow integration and batch mode.
Be prepared for a steep learning curve; it has a lot of options.
Shotwell is a very capable package for processing and organising photos in Linux. It is now part of Ubuntu. See http://yorba.org/shotwell
Google Picasa was previously available for Linux, built against the Wine libraries rather than as a native app, but as of 3.5 and later Linux support is discontinued.
Lightzone, a previously commercial program, is now open source. http://lightzoneproject.org/
been using geeqie for years and it has saved me countless hours. can't even use any other viewer any longer due to how spoiled I am on geeqie's ability and speed.
while being able to view images as fast as my wheel mouse can scroll is awesome, and the ability to open every file from geeqie is also nice.
its a one stop viewer that is always installed on all my linux builds. in my opinion, it should be the default image viewer for every RAW image album you have to sort.
After trying all the above I finally stumped up money for Corel Aftershot Pro 2. It's not free, but its UI and stability beat all the others IMHO. Also the manual is well written and clear.
Having said that, for critical work I still fire up my windows pc and use Lightroom. Adobe are still the best in this area.
But with Aftershot/Gimp for stills and now Lightworks for video, Linux is getting close to being usable for serious photo/video work.
To edit Canon's CR2 RAW files, Canon's Digital Photo Professional will run under wine. The big advantage is that it provides the same results under Linux that it does under Windows. Canon's demosaicing is very good. I have experienced no crashes.
Adjustments are available for brightness, white balance, "shot settings" and "picture style", overall contrast, shadow and highlight contrast, color tone, color saturation, and sharpness. Alternately, each primary color can be adjusted with an arbitrary curve.
Noise reduction and lens aberration correction is available. Images can be rotated and cropped. Dust removal and stuck pixel repair can be done.
All operations affect the entire image, which means that things like sharpening just one part of the image, or applying a vignetting mask, are not possible.
KPhotoAlbum is a cataloging application that supports RAW files. I use it to sort, preview, discard, and tag images before passing them to something else to potentially edit.