Blind identification algorithm for retouched images based on Bi-Laplacian

Image retouching is a technique widespreadly used in image tampering.To implement image retouching blind detection,a blind identification algorithm for image was proposed.The algorithm firstly searched for each block in image,and inserted each block into the KD tree,thus obtaining the same value or the nearest match block.Then it used the hierarchical clustering of the position vector to eliminate the scattered matching.Finally,it applied the 7-tap Laplacian filter to count weight of zero connectivity of suspicious blocks to eliminate false positives,thereby located accurately the tampered area.The experimental results show that this method can efficiently and accurately identify the use of a class of image manipulation techniques for uncompressed images and high quality compressed images.When it is applied to the images of higher compression levels,accurate results are also obtained if the region that has been retouched is sufficiently large.