Make a drawing and take a picture of it, and the free iOS app Tunetrace turns it into music. Well, sort of: Abstract minimalism sounds boring, but selfies (self-portraits taken with a mobile device) are rather melodic. Tunetrace — which Queen Mary University of London company QApp released this spring on iPhone, iPod Touch and iPad — is a novelty hinting at the potent idea of combining machine vision and procedural music. Open Tunetrace and snap a photo, and the app uses machine vision to find the lines in an image, then assign each line a tone. Hit play, and twinkling white lights trace each line playing a note. When lines intersect, the lights reverse course and play an alternate tone — so a drawing of a cross generates a two-tone oscillation, while an Erykah Badu tattoo encodes a little ditty. Designed for ages 4 and up, Tunetrace has online teaching instructions for middle and high schoolers.