How do I start studying Gabor Filters ?
You know what I actually found really useful, Gabor's original paper, "Theory of Communication":

http://redwood.berkeley.edu/w/images/b/b6/Gabor.pdf

Of particular interest is how Gabor used banks of reeds, tuned to different frequencies, to visualise his filters. For me this led to a good conceptual understanding, especially of the uncertainty principle, before diving into the mathematics.