title: Key differences between Core Image and GPUImage
body: <p>What are the major differences between the Core Image and GPUImage frameworks (besides GPUImage being open source)?  At a glance their interfaces seem pretty similar... Applying a series of filters to an input to create an output.  I see a few small differences, such as the  easy to use LookupFilter that GPUImage has.  I am trying to figure out why someone would choose one over the other for a photo filtering application.</p>