Search

The traditional CBIR (Content based image retrieval) global descriptor can't extract local features effectively, while the SIFT (Scale Invariant Feature Transform) algorithm only focus on local object features matching, and can not satisfy the need of fuzzy CBIR queries based on visual feeling. In view of this contradiction, an approach is proposed based on image salient region, in which the SIFT algorithm and the traditional CBIR color descriptors are combined, the entropy of salient point is used to distinguish the salient and non-salient regions of image. We use centroid weighted histogram and dominant color descriptor of MPEG-7 to describe the salient and non-salient region respectively, which not only effectively extract the local features of image objects, but also overcome the SIFT algorithm for high dimension, and vulnerable to interference with the global features. Experiments show that for general image retrieval application, the proposed method has better retrieval performance, with better robustness for geometric and perspective transform.

Image watermark resistant to geometric attacks is the focus and difficulty point in the current research on watermarking. This paper proposes a Wavelet-domain watermarking algorithm against geometric attacks based on the SUSAN feature points matching. The algorithm embeds watermarks into each sub-band of the wavelet coefficients of the host image with different strength adaptively adjusted in terms of the gray level of them. The choice of the embedding strategy effectively guarantees good transparency and strong robustness of the watermark. Furthermore, the paper improves the SUSAN operator, to extract the feature points robust to geometric distortion from the watermarked image. Before watermark detection, it uses the transformation of the corresponding points to correct geometric distortion, which ensures successful extraction of the watermark. Experiment results show that the proposed algorithm has good transparency, and it is also robust to common image processing and geometric attacks.