The demonstration application is a contour-based image retrieval prototype system for the large scale database. By simulating hierarchical image processing of human visual system, it is able to retrieve relative images from large scale database according to the contour of the object in an image. In most of situation, users usually want to find images with certain contours without caring its size or location in the image. But most existing algorithms are not able to deal with such invariance problems. The existing retrieval systems usually require that the objects in the query image and in the retrieved image should have the same position and almost the same size. Different from existing algorithms, the system is developed to address these invariance issues, such as the shift-invariance and scale-invariance problem. Furthermore, the system allows two kinds of query image: a hand-drawn sketch or a natural image, which brings the better interactive user experiment and the convenience for those who don't well in drawing. The system could perform an image search from 4 million images quickly, and the response time for each query is about 3~5 seconds.