A blind identification algorithm for image copy-paste tampering with geometric invariance was proposed in this study.Firstly

gray level and gray structure are defined

the image is divided into blocks according to the gray levels of pixels

and the suspicious blocks in the image is positioned through the gray structure;Secondly

phase correlation is made for each group of suspicious block based on logarithm polar coordinate transformation

and the tampering regions are located preliminarily;Finally

the rotation angle

scale and translation measurements are calculated precisely

and the tampering regions are positioned.The experimental results show that our algorithm performs well against copy-rotate/scale-paste tampering

and its detection efficiency and robustness are better than the existing algorithms.