I know just wanted to learn the basics of ditherinig and imo it wasn't a waste of my time cuz i learnt sth.

Whether this is PA or not, you forgot to link your reference - giving the impression to everyone that you didn't use one at all. And if there was anyone who didn't know who Darth Vader was, they'd be lead into thinking you created the character.

I'm going to assume you saved some of the work in progress frames with such a large piece. It would be very convenient if you happened to have not.

well great job then...huge waste of 5 whole days, though...since all you did was blatantly trace an existing picture, which requires no creativity at all and is frowned upon here...personally I like the preview better than the actual piece itself...

btw I really applaud your ability to manually replicate Floyd and Steinberg's dithering algorithm. To me this shows great skills in understanding the aforementioned algorithm and applying the principles behind it to emulate your reference image with only 4 colours. Shame, though, I woulda just used photoshop. Much quicker and it means you don't have to waste all that time learning how a ditehering algorithm works, and then trying to replicate it manually.

jus' sayin'

weird...it took me less than 120 seconds to achieve similar results by just colour reducing one of darth vader's pictures in photoshop