Whether you prefer a pocket sized point-and-shoot or a hefty SLR with a bag full of lenses, Linux supports your digital photography needs. Most cameras offer plug-and-play simplicity for transferring images from the camera to the computer, and you have a wide range of choices for managing and editing your photos -- even the Raw formats preferred by professional shutterbugs. Linux also supports high-quality printer output for when you are ready to hang something on the wall.
The majority of digital cameras on the market today use removable flash storage cards, but include a USB port to enable direct transfer of images to a computer without removing the card. Modern Linux distributions recognize when a USB-connected digital camera is attached, and will automatically link to it so you can access the photos. This is done through the gphoto2 library, so if you are unsure whether the camera you have is supported, the gphoto site is the definitive resource to check. Depending on the distribution and desktop environment you use, one of several application programs may automatically launch to help you transfer images from a connected camera; which application is a setting that you can configure. If all else fails, though, you can always plug the flash memory card from your camera into a USB card reader and transfer the photos to your computer like any other file.
The most well-known photo organizing applications in Linux are F-Spot, DigiKam, and Picasa--any one of which may be the application your distribution launches automatically. All three allow you to organize and tag your photos, create and manage collections, and make essential edits like cropping and color adjustments. You can also automate batch operations for adjusting entire sets of images, and export copies of your images and collections for sharing on the Web.
Less expensive cameras generally store photos in JPEG format, which is readable by any application and can be shared and emailed without adjustment. Pricier cameras often shoot in what is called "Raw mode," meaning that the camera saves image data in a special format unique to the camera manufacturer and sensor. Canon's Raw formats use the file extensions .CRW or .CR2; Nikon's use .NEF or .NRW, and so on. Raw mode files must be converted into a standard image format before they can be shared or used in general-purpose applications, and Raw conversion applications cater to pro photographers' desire to tweak and adjust a wide variety of image parameters.
F-Spot, DigiKam, and Picasa all support basic Raw conversion, but enthusiasts may prefer to use a dedicated Raw photo processor. Free software converters like Rawstudio and UFRaw are popular and come with most major Linux distributions. There are also non-free, commercial alternatives for Linux, such as LightZone and Bibble Pro.
However you manage your image collection, there will be occasions when you need more editing power than the built-in adjustments of your image management program provide. The raster graphics editors Krita and GIMP are the preferred tools for every editing task from dirt and scratch removal to creating complex works of art. Both provide a myriad of tools, adjustments, layer effects, filters, and plugins. Both support pressure-sensitive pen tablets for making finer marks than a mouse can provide. Plugins are often developed separately from the image editing application and can rapidly make important new features available, such as noise removal, refocusing, and tone-mapping high dynamic range (HDR) images.
A third tool worth checking into if you need high-quality output is Cinepaint; Cinepaint shares some of its history with GIMP, but is built specifically for editing high-bit-depth images in film retouching. It does not have as many plugins and effects, but if you are worried about retaining high-quality image data, it is a good choice.
Almost any image editing task is possible in Krita and GIMP, but there are situations when a special purpose tool -- such as stitching multiple photos together into a larger, panoramic shot. Hugin is just such a tool; with it you can seamlessly blend multiple images into a larger image, create 360-degree panoramas, and much more. Hugin can also remove distortion and blur caused by lens imperfections and wide angles.
Linux can print high-quality photo output on laser and inkjet printers, including most of those that use six colors of ink (CcMmYK). The Gutenprint project maintains device drivers for printers.
Finally, most photographers' worst nightmare is losing images, but Linux can help you there, too. The open source program PhotoRec can recover accidentally deleted photos from all sorts of flash-based storage cards, at no cost.
All of the projects mentioned provide resources you can use to take better advantage of the software. F-Spot has a good users' guide on its site, Digikam has a handbook and wiki, and Picasa has an online support forum. Krita and GIMP both provide manuals, and Hugin provides an extensive collection of hands-on tutorials that are very helpful for using such a powerful tool.
For general help regarding digital photography topics including the ins-and-outs of Raw conversion, the best options are digital photography forums like The Luminous Landscape or Photo.net, where photographers on all operating systems gather. Last but certainly not least is the photography-centric social networking site Flickr, where you can find discussion groups dedicated to photo topics but also digital photography tools such as the Linux software mentioned above. There you can get practical help with any software application, as well as immediate feedback through sharing your work and exploring the pictures uploaded by others.