i'm sorry, i just had an orgasm.
Surely. But if you master the technique, It won't limit your imagination no more (like a friend of mine says).
E.G.. like in cases when you want to draw something, but can not due to the lack of skill.
Yes it's pixel by pixel. But I want to mention that while drawing, I was looking at an oil painting of a glass by Noodga Manana, because the colours there are more simple and understandable, than in a photo. Though, I was not just painting over it, because there will be no understanding of how to do it. I think it is easy to notice by eye.
So, if there is a reference pic needed, I can post a link to a painting - http://re.foto.radikal.ru/0707/a1/913cd2d5d278.jpg