Some of you may be familiar with G'MIC, the rather extensive image processing language created by David Tschumperlé that has a very popular plug-in for GIMP.
If you're a fan, here's a nice little treat for you. David has started a blog about image processing with open source software:
If you'd like a front seat to some of the more technically interesting things going on behind the scenes at G'MIC, this would be a good blog to follow I think. He's already come out of the gate with a neat 3D colorcube investigation of some images (seen above, Mairi).