Most digital cameras will by default save photos as JPEG files, and it’s easy to see why: they’re small, can be saved and reloaded quickly, and are supported by just about every graphics package available.

Switching to your camera’s RAW format (if it has one) can be worthwhile, though: you’ll get minimally processed images containing all the data from your camera sensor, giving you much more precise control over how the final photo will look. RAW images are also huge, and can’t be opened by nearly as many tools, but there are still some great free options available – and even though it’s only in alpha, the open source GTKRawGallery is already a promising contender.

The program opens with a fairly conventional photo manager. A thumbnail browser helps you navigate your image library. You can organise your photos into custom libraries. There’s a basic search tool, a tag editor (EXIF, IPTC and XMP), batch file renamer and more. And this isn’t just for RAW files – the program can work with all the more standard formats, too.

Double-clicking an image opens it in a new window for processing. This doesn’t work so well for viewing, as its toolbar is way too small, and there seems to be a distinct lack of keyboard and mouse shortcuts (don’t expect to use the “+” and “-” keys or the mouse wheel to zoom in and out, for instance – you have to use the toolbar buttons). But if you just want to get on with processing your photo then the news is better, with GTKRawGallery organising a host of functions into eight tabs: “Exif”, “Keywords”, “Dcraw”, “Enhance”, “Transform”, “Effects”, “History” and “Metadata”.

A host of photo processing options are just a click or two away

Experienced photographers might start with the Dcraw panel, where they’ll find tweaks for white balance, gamma, black point, saturation, brightness and more. There are denoise and media filters, along with a chromatic aberration tool and colour management options. You can save your preferred settings as presets, too, making it easier to reapply them consistently on future images.

Clicking the Enhance tab reveals plenty of additional options, including controls for temperature, levels, curves, highlights, shadows, exposure and more.

But if this is all just a little too complicated, the Transform tab has more straightforward tools: flip, rotate, resize and crop, red eye removal and so on.

A fairly standard (although well implemented) list of effects ranges from the practical (sharpen, unsharp mask, reduce noise) to the more artistic (oil paint, charcoal, sketch). All of these can be configured in various ways to customise the results.

And when you’re happy, any selected images can be burned to disc, emailed, or uploaded to Facebook, Flickr, Picasa or Facebook.

GTKRawGallery has some issues. The interface doesn’t always work as you might expect, for instance, and its performance isn’t always the best. That’s no surprise for an alpha, though, and the program already has some very impressive features and functionality. If you’re looking for a powerful and free photo processing tool then this is one project you’ll want to watch.