If you’re looking to enhance the quality of your digital photos then there’s not exactly a shortage of free tools offering to help. But most are rather basic, oriented firmly at beginners, and if you’re an old hand at image processing then they’ll probably leave you wanting more.

Raw Therapee is different. There’s no text tool here, no paint options, no “special effects”; instead it’s all about image processing, providing ways to correct, adjust and enhance your photos. But if that’s what you’re after then it’s very good indeed (and, conveniently, it has versions for Windows, Mac OS X and Linux).

The program opens conventionally enough, with a thumbnail browser. Navigate to the folder containing your photos to see their thumbnails (RAW, JPG, TIF and PNG files are supported), then double-click anything which needs work to open it properly.

If you’d like to jump right in then the best place to start is with the panel on the right, where Raw Therapee’s processing options are organised into five main categories: Exposure, Detail, Color, Transform and Raw. And browsing any of these will quickly reveal just how powerful this program can be.

Browse the panel on the right for quick access to all Raw Therapee's image processing features

RAW image quality may be enhanced by a good range of demosaicing algorithms, for instance: AMaZE, DCB, fast, AHD, EAHD, HPHD & VNG4.

Colour handling controls cover everything from simple channel mixing and RGB curves, to white balance, HSV, vibrance and more.

Would you like to enhance details? The Detail pane contains no less than seven options: Sharpening, Edges, Microcontrast, Impulse Noise Reduction, Noise Reduction, Defringe and Contrast by detail levels. And each of these is highly configurable, so for example select Sharpening and you can choose the algorithm (Unsharp Mask or RL Deconvolution), radius, amount, threshold and more.

And you also get great exposure controls, a stack of powerful lens/ geometry correction tools, EXIF/ IPTC metadata editing, batch processing, command line control, lots of configuration options, and the list goes on.

It’s not all good news. A lack of documentation will be a problem for some. The interface didn’t always work as we expected. Performance was sometimes an issue, too, and on one occasion our 64-bit version locked up for no apparent reason.

These were all minor problems, though, when compared with the huge amount of image processing power on offer here. And so if you’re tired of the basic correction tools offered by standard image editors, and need something more, give Raw Therapee a try (ideally the 64-bit version, if you can run it, for its improved memory handling): we think you’ll be impressed.