Gimp is the oddity here, as it’s both free and open source, meaning you can change any part of the code to improve the experience, if you have the know-how...
However, unaltered it’s still a good alternative to Photoshop if you want to dip your toes into the world of photo editing for free.
The basic interface is slightly reminiscent of Adobe’s offering, though doesn’t look nearly as polished. A lot of the major tools are here, such as Clone Stamp, Heal and Brush, and work in much the same way as you’d expect. Gimp allows a certain degree of non-destructive editing, thanks to supporting Layers and Masks, though this is a slow and laborious affair.
Adjustments, such as Curves, Layers or Hue/Saturation, are not available on alternative Layers, and as such they will be permanently applied to your images. You can get around this by duplicating your Layer for each application, though you won’t be able to change the settings at a later date as you can in Photoshop.
None of the features are ground-breaking, but they are plentiful and work well. There’s a vast array of Filters, which allow a lot of creative freedom, though as a whole the software seems to plod along at a leisurely pace rather than sprint with purpose.
Unfortunately Gimp won’t process RAW files, meaning you will have to use an external RAW converter. It also appeared quite slow in testing. Our version (2.8) was prone to crashing, making it less than suitable for a heavy workflow.
Gimp has other applications beyond photos. There are tools for artists, animators and designers built into the code, meaning there are a lot of benefits to trying this freebie before searching for more specific packages.
It may have more features than some of the other options in test, but the lack of reliability and extreme slowness are both limiting factors which count heavily against it. Of course, given the fact that it’s free, you really don’t have anything to lose if you wish to give it a try.
Lots of features
RAW conversion: No
System requirements: Mac OS X 10.12/Windows XP or higher