Feature space design for image recognition with image screening

This paper describes a two-stage recognition method that reduces the calculation load of correlation and improves recognition accuracy in statistical image recognition. It consists of an image screening and recognition stage. Image screening selects a candidate set of subimages that are similar to the object class using a lower dimensional feature vector. Since recognition is made for the selected subimages set using a higher dimensional feature vector, overall recognition efficiency is improved. The classifier in recognition designed from the selected subimages also improves recognition accuracy because selected subimages are less contaminated than the original ones. A screening criterion for measuring overall efficiency and accuracy of recognition is introduced to be exploited in designing the feature spaces of image screening and recognition. The results of experiments for the eye- and mouth-area detection in face images and text-area detection in document images show that the designed feature spaces improve recognition accuracy and more efficiency than does the conventional one-stage recognition method.