We propose two novel local transform features: local gradient patterns (LGP) and binary histograms of oriented gradients (BHOG). LGP assigns one if the neighboring gradient of a given pixel is greater than its average of eight neighboring gradients and zero otherwise, which makes the local intensity variations along the edge components robust. BHOG assigns one if the histogram bin has a higher value than the average value of the total histogram bins, and zero otherwise, which makes the computation time fast due to no further postprocessing and SVM classification. We also propose a hybrid feature that combines several local transform features by means of the AdaBoost method, where the best feature having the lowest classification error is sequentially selected until we obtain the required classification performance. This hybridization makes face and human detection robust to global illumination changes by LBP, local intensity changes by LGP, and local pose changes by BHOG, which considerably improves detection performance. We apply the proposed features to face detection using the MIT+CMU and FDDB databases and human detection using the INRIA and Caltech databases. Our experimental results indicate that the proposed LGP and BHOG feature attain accurate detection performance and fast computation time, respectively, and the hybrid feature improves face and human detection performance considerably.

This study presents a new method to track driver's facial states, such as head pose and eye-blinking in the real-time basis. Since a driver in the natural driving condition moves his head in diverse ways and his face is often occluded by his hand or the wheel, it should be a great challenge for the standard face models. Among many, Active Appearance Model (AAM), and Active Shape Model (ASM) are two favored face models. We have extended Discriminative Bayesian ASM by incorporating the extreme pose cases, called it Pose Extended-Active Shape model (PE-ASM). Two face databases (DB) are used for the comparison purpose: one is the Boston University face DB and the other is our custom-made driving DB. Our evaluation indicates that PE-ASM outperforms ASM and AAM in terms of the face fitting against extreme poses. Using this model, we can estimate the driver's head pose, as well as eye-blinking, by adding respective processes. Two HMMs are trained to model temporal behaviors of these two facial features, and consequently the system can make inference by enumerating these HMM states whether the driver is drowsy or not. Result suggests that it can be used as a driver drowsiness detector in the commercial car where the visual conditions are very diverse and often tough to deal with.

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