I took a portrait class by Marilyn Belford thru Quilt University (now Academy of Quilting) and it was amazing!!
http://academyofquilting.com/faculty/marilyn-belford/ This link lists her classes and bio.
She was available for help every step of the way, and it was one of the best classes I've ever taken. I made this quilt during my class:
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She also has an art quilt class, where you can create art pictures. I've not taken it, but if it's anything like the portrait class, I highly recommend it. She also has a book on how to create the portrait pics that's very informative.