Biblio

A machine translation system that can convert South African Sign Language video to English audio or text and vice versa in real-time would be immensely beneficial to the Deaf and hard of hearing. Sign language gestures are characterised and expressed by five distinct parameters: hand location; hand orientation; hand shape; hand movement and facial expressions. The aim of this research is to recognise facial expressions and to compare the following feature descriptors: local binary patterns; compound local binary patterns and histogram of oriented gradients in two testing environments, a subset of the BU3D-FE dataset and the CK+ dataset. The overall accuracy, accuracy across facial expression classes, robustness to test subjects, and the ability to generalise of each feature descriptor within the context of automatic facial expression recognition are analysed as part of the comparison procedure. Overall, HOG proved to be a more robust feature descriptor to the LBP and CLBP. Furthermore, the CLBP can generally be considered to be superior to the LBP, but the LBP has greater potential in terms of its ability to generalise.

Descriptors such as local binary patterns perform well for face recognition. Searching large databases using such descriptors has been problematic due to the cost of the linear search, and the inadequate performance of existing indexing methods. We present Discrete Cosine Transform (DCT) hashing for creating index structures for face descriptors. Hashes play the role of keywords: an index is created, and queried to find the images most similar to the query image. Common hash suppression is used to improve retrieval efficiency and accuracy. Results are shown on a combination of six publicly available face databases (LFW, FERET, FEI, BioID, Multi-PIE, and RaFD). It is shown that DCT hashing has significantly better retrieval accuracy and it is more efficient compared to other popular state-of-the-art hash algorithms.