Firefly

This picture is really nice. Firefly is my favorite pony too. I still have my original toy of her. I wanted to ask, I'm making a shirt with her on it, hand painting, in the new style and the original style. May I use this picture for my shirt? The shirt is for my own personal wear, I'm not selling it or anything, and when it's finished I would like to post a picture of it on deviant and reference you in the credit section of course. A lot of the pictures I find online of her from her movie are too small for a shirt reference, and this drawing just captures her perfectly to me. ^.^