Thank you quilt4u.
I took a class from Marilyn Belford, online at www.quiltuniversity.com and she showed us how to do it. First you posterize your picture, then you enlarge to a life size, trace onto tracing paper the different shapes where the shadows are, then you find the right colors and shades to fit in that spot. Use steam a seam 2 to bond the fabric to the foundation piece, and then sew it down. Of course there are more steps, but this is the jist of the process. I think the hardest part was to find the right fabrics for the right shadows. It was a fun class.