Image forgery detection using characteristics of background noise

There is a part of background noise in digital image which comes from imaging process or digital compression. The noise characteristics between image forgery area and the other area would be different if images with different noise levels are spliced together. Base on a method of channel SNR estimation which uses high order statistic characteristics, a new algorithm is proposed in this paper for blind estimation of image background noise. We can detect the forgery parts by dividing image into some sub-blocks and computing the noise variance of each ones. The problem of unknown original signal in the method of high order statistic characteristics has been solved by adding noise again and the blind estimation of detected image background noise has realized. Experiment results show the algorithm is effective in estimating noise variance and detecting forgery parts. In addition, there is little influence on the experiment results after image scaling and compression. So the algorithm has good robustness.