Poster Work

I am hoping to create a concept poster for a film I am working on. I've tried to do it myself, but it's just not working out like I had hoped. I have an actress who has posed in front of a green screen. I readily admit, it wasn't pulled tight like it should have been. I would like her to be edited to appear reptilian. Claws, scales, the works. I can provide a sample poster I have done of a different character for reference of the style and feel of the poster I'm hoping to have created.