A new feature extraction method called as 2DDM is proposed based on discrete cosine transform(DCT) and two-dimensional maximum margin criterion(2DMMC).It is also proven that the 2DMMC can be directly implemented in the DCT domain and the classification results by the measure of Euclidean distance are exactly the same as the one obtained from the spatial domain.For images compressed using the DCT,2DMMC can be directly implemented so that the inverse DCT(IDCT) can be skipped and the computational cost is redu...