A compressed domain scheme for classifying block edge patterns

Detecting and classifying edge components in images find a wide range of applications from perceptually improved coding schemes to content-based searches. A fast and systematic scheme is proposed to classify the edge orientation of each block in discrete cosine transform (DCT)-compressed images. Derived from a simple, but acceptable, pixel-domain algorithm, the proposed scheme performs directly on DCT coefficient domain and, thus, saves the arithmetic operations by a considerable amount. The performance of the proposed method is validated by the experiments against various natural images.