Comparing Evolutionary Operators, Search Spaces, and Evolutionary Algorithms in the Construction of Facial Composites

Facial composite construction is one of the most successful applications of interactive evolutionary computation. In spite of this, previous work in the area of composite construction has not investigated the algorithm design options in detail. We address this issue with four experiments. In the first experiment a sorting task is used to identify the 12 most salient dimensions of a 30-dimensional search space. In the second experiment the performances of two mutation and two recombination operators for interactive genetic algorithms are compared. In the third experiment three search spaces are compared: a 30-dimensional search space, a mathematically reduced 12-dimensional search space, and a 12-dimensional search space formed from the 12 most salient dimensions. Finally, we compare the performances of an interactive genetic algorithm to interactive differential evolution. Our results show that the facial composite construction process is remarkably robust to the choice of evolutionary operator(s), the dimensionality of the search space, and the choice of interactive evolutionary algorithm. We attribute this to the imprecise nature of human face perception and differences between the participants in how they interact with the algorithms. Povzetek: Kompozitna gradnja obrazov je ena izmed najbolj uspešnih aplikacij interaktivnega evolucijskega ra?cunanja. Kljub temu pa do zdaj na podro?cju kompozitne gradnje niso bile podrobno raziskane možnosti snovanja algoritma. To vprašanje smo obravnavali s štirimi poskusi. V prvem je uporabljeno sortiranje za identifikacijo 12 najbolj izstopajo?cih dimenzij 30-dimenzionalnega preiskovalnega prostora. V drugem primerjamo u?cinkovitost dveh mutacij in dveh rekombinacijskih operaterjev za interaktivni genetski algoritem. V tretjem primerjamo tri preiskovalne prostore: 30-dimenzionalni, matemati?cno reducirani 12-dimenzionalni in 12-dimenzionalni prostor sestavljen iz 12 najpomembnejših dimenzij. Na koncu smo primerjali uspešnost interaktivnega genetskega algoritma z interaktivno diferencialno evolucijo. Rezultati kažejo, da je proces kompozitne gradnje obrazov izredno robusten glede na izbiro evolucijskega operatorja(-ev), dimenzionalnost preiskovalnega prostora in izbiro interaktivnega evolucijskega algoritma. To pripisujemo nenatan?cni naravi percepcije in razlikam med interakcijami uporabnikov z algoritmom

Interactive evolutionary generation of facial composites for locating suspects in criminal investigations

Statistical appearance models have previously been used for computer face recognition applications in which an image patch is synthesized and morphed to match a target face image using an automated iterative fitting algorithm. Here we describe an alternative use for appearance models, namely for producing facial composite images (sometimes referred to as E-FIT or PhotoFIT images). This application poses an interesting real- world optimization problem because the target face exists in the mind of the witness and not in a tangible form such as a digital image. To solve this problem we employ an interactive evolutionary algorithm that allows the witness to evolve a likeness to the target face. A system based on our approach, called EFIT-V, is used frequently by three quarters of UK police constabularies

A comparison of search spaces and evolutionary operators in facial composite construction

In this paper a series of experiments concerning the use of IEAs in the creation of facial composites are reported. A human evaluation based search space, which is itself a subspace of a larger search space, is created. The human reduced search space is used to compare two mutation operators and two recombination operators in an IEA. A mathematically reduced search space is constructed from the larger search space. The facial composite process is performed in the three search spaces. No statistically significant differences are found between the performances of the operators or the search spaces