I dabble in graphic art, having been a sketch artist for many years, but I find myself tempted to at least get a starting point by using images from the good old internet. I typically use them to help me establish scale, or to get my idea more concretely formed. The problem is that, after editing these images beyond recognition in many cases, I come to like what I've made them into and don't want to start from scratch. My question: is there a percentage of editing that can be done to an image that frees me from copyright or, because I used it start with, is it just stealing no matter what? Factual (legal) and philosophical answers are both quite welcome. Thanks!