Demographic analysis of facial landmarks

1. A method comprising:

identifying a set of training vectors, wherein each training vector is mapped to either a male gender or a female gender, and wherein each training vector represents facial landmarks derived from a respective facial image;

identifying an input vector of facial landmarks, wherein the facial landmarks of the input vector are derived from a particular facial image;

selecting, from the input vector, a feature vector containing a subset of the facial landmarks, wherein selecting the feature vector comprises determining a training matrix representing the training vectors, determining a covariance matrix of the training matrix, and using a random forest technique to (i) build a plurality of trees, wherein each node of each tree in the plurality of trees represents a random selection of the facial landmarks, (ii) calculating the Gini importance of the facial landmarks, and (iii) based on the calculated Gini importance, determining the feature vector;

performing, by a computing device, a weighted comparison between the feature vector and each of the training vectors; and

based on a result of the weighted comparison, classifying the particular facial image as either the male gender or the female gender.

2. The method of claim 1 , wherein the feature vector is less than one-half the size of the input vector.

3. The method of claim 1 , wherein the feature vector is less than one-quarter the size of the input vector.

4. The method of claim 1 , wherein selecting the feature vector comprises using a memetic algorithm to select the feature vector, wherein the memetic algorithm determines the fitness of a candidate feature vector based on a classification accuracy of a facial image associated with the candidate feature vector, and wherein the memetic algorithm uses a recombination process that produces a child feature vector of a size no greater than that of the each parent feature vector of the child feature vector.

5. The method of claim 4 , wherein a non-selected feature vector contains facial landmarks from one of the training vectors that are not in the candidate feature vector, and wherein using the memetic algorithm comprises:

ranking the features in the candidate feature vector and the non-selected feature vector each in order of importance according to a univariate filter; and

modifying the candidate feature vector by adding the m highest-ranked features of the non-selected feature vector into the candidate feature vector, and removing the n lowest-ranked features from the candidate feature vector.

6. The method of claim 5 , wherein modification of the candidate feature vector is performed for all m and n less than a particular value, and wherein a variation of the candidate feature vector for which the selected m and n result in a sufficiently high fitness as determined by the memetic algorithm is selected as the feature vector.

7. The method of claim 1 , wherein selecting the feature vector comprises using a locality preserving projection to select the feature vector, wherein using the locality preserving projection comprises:

constructing a graph representing the training vectors, wherein each vertex in the graph corresponds to one of the training vectors, and wherein each pair of vertices in the graph are connected with a respective edge with a uniform weight if the associated training vectors map to the same gender; and

determining the feature vector based eigenvectors of an equation involving a training matrix representing the training vectors and an adjacency matrix of the graph.

8. The method of claim 1 , wherein selecting the feature vector comprises:

determining a training matrix representing the training vectors;

determining a covariance matrix of the training matrix; and

determining the feature vector based on an eigenvector of the covariance matrix.

9. An article of manufacture including a non-transitory computer-readable medium, having stored thereon program instructions that, upon execution by a computing device, cause the computing device to perform operations comprising:

identifying a set of training vectors, wherein each training vector is mapped to either a male gender or a female gender, and wherein each training vector represents facial landmarks derived from a respective facial image;

identifying an input vector of facial landmarks, wherein the facial landmarks of the input vector are derived from a particular facial image;

selecting, from the input vector, a feature vector containing a subset of the facial landmarks, wherein selecting the feature vector comprises determining a training matrix representing the training vectors, determining a covariance matrix of the training matrix, and using a random forest technique to (i) build a plurality of trees, wherein each node of each tree in the plurality of trees represents a random selection of the facial landmarks, (ii) calculating the Gini importance of the facial landmarks, and (iii) based on the calculated Gini importance, determining the feature vector;

performing, by a computing device, a weighted comparison between the feature vector and each of the training vectors; and

based on a result of the weighted comparison, classifying the particular facial image as either the male gender or the female gender.

10. The article of manufacture of claim 9 , wherein selecting the feature vector comprises using a memetic algorithm to select the feature vector, wherein the memetic algorithm determines the fitness of a candidate feature vector based on a classification accuracy of a facial image associated with the candidate feature vector, and wherein the memetic algorithm uses a recombination process that produces a child feature vector of a size no greater than that of the each parent feature vector of the child feature vector.

11. The article of manufacture of claim 10 , wherein a non-selected feature vector contains facial landmarks from one of the training vectors that are not in the candidate feature vector, and wherein using the memetic algorithm comprises:

ranking the features in the candidate feature vector and the non-selected feature vector each in order of importance according to a univariate filter; and

modifying the candidate feature vector by adding the m highest-ranked features of the non-selected feature vector into the candidate feature vector, and removing the n lowest-ranked features from the candidate feature vector.

12. The article of manufacture of claim 11 , wherein modification of the candidate feature vector is performed for all m and n less than a particular value, and wherein a variation of the candidate feature vector for which the selected m and n result in a sufficiently high fitness as determined by the memetic algorithm is selected as the feature vector.

13. The article of manufacture of claim 9 , wherein selecting the feature vector comprises using a locality preserving projection to select the feature vector, wherein using the locality preserving projection comprises:

constructing a graph representing the training vectors, wherein each vertex in the graph corresponds to one of the training vectors, and wherein each pair of vertices in the graph are connected with a respective edge with a uniform weight if the associated training vectors map to the same gender; and

determining the feature vector based eigenvectors of an equation involving a training matrix representing the training vectors and an adjacency matrix of the graph.

14. The article of manufacture of claim 9 , wherein selecting the feature vector comprises:

determining a training matrix representing the training vectors;

determining a covariance matrix of the training matrix; and

determining the feature vector based on an eigenvector of the covariance matrix.

15. The article of manufacture of claim 9 , wherein the feature vector is less than one-half the size of the input vector.

16. A computing system comprising:

at least one processor;

data storage; and

program instructions, stored in the data storage, that upon execution by the processor cause the computing system to perform operations including:

identifying a set of training vectors, wherein each training vector is mapped to either a male gender or a female gender, and wherein each training vector represents facial landmarks derived from a respective facial image;

identifying an input vector of facial landmarks, wherein the facial landmarks of the input vector are derived from a particular facial image;

selecting, from the input vector, a feature vector containing a subset of the facial landmarks, wherein selecting the feature vector comprises determining a training matrix representing the training vectors, determining a covariance matrix of the training matrix, and using a random forest technique to (i) build a plurality of trees, wherein each node of each tree in the plurality of trees represents a random selection of the facial landmarks, (ii) calculating the Gini importance of the facial landmarks, and (iii) based on the calculated Gini importance, determining the feature vector;

performing, by a computing device, a weighted comparison between the feature vector and each of the training vectors; and

based on a result of the weighted comparison, classifying the particular facial image as either the male gender or the female gender.

17. The computing system of claim 16 , wherein selecting the feature vector comprises using a memetic algorithm to select the feature vector, wherein the memetic algorithm determines the fitness of a candidate feature vector based on a classification accuracy of a facial image associated with the candidate feature vector, and wherein the memetic algorithm uses a recombination process that produces a child feature vector of a size no greater than that of the each parent feature vector of the child feature vector.

18. The computing system of claim 16 , wherein selecting the feature vector comprises using a locality preserving projection to select the feature vector, wherein using the locality preserving projection comprises:

constructing a graph representing the training vectors, wherein each vertex in the graph corresponds to one of the training vectors, and wherein each pair of vertices in the graph are connected with a respective edge with a uniform weight if the associated training vectors map to the same gender; and

determining the feature vector based eigenvectors of an equation involving a training matrix representing the training vectors and an adjacency matrix of the graph.

19. The computing system of claim 16 , wherein selecting the feature vector comprises:

determining a training matrix representing the training vectors;

determining a covariance matrix of the training matrix; and

determining the feature vector based on an eigenvector of the covariance matrix.

20. The computing device of claim 16 , wherein the feature vector is less than one-half the size of the input vector.