Human and Computer Evaluations of Face Sketches with Implications for Forensic Investigations

Because sketches represent the original faces in a much concise yet recognizable form, they play an important role in criminal investigations, human perceptions and biometrics. In this work, we compared the performances of humans and a PCA-based algorithm in recognizing face sketches. A total of 250 sketches of 50 subjects were involved. All sketches were drawn manually by five artists (each artist drew 50 sketches, one for each subject). Experiments were carried out by matching sketches in a probe set to photos in a gallery set. This study resulted in the following findings: (i) A large inter-artist variation in sketch recognition rate was observed; (ii) Fusing sketches from different artists significantly improved the performance; (iii) Human performance seems correlated with that of the algorithm; (iv) The algorithm was superior with sketches of less distinctive features, while humans used tonality (or pigmentation) cues more efficiently.