For the tamper method of the same image copy-paste, a new tampering forensics scheme is proposed with the consistency of illuminant chromaticity in the three color channels, RGB, as the identification indicator of the image. The experimental results show that the detection way, which use the chromaticity consistency of different objects in the image as the features of image tampering forensics, works well, for the modifications of copy-paste and scaling on the pasted region in the same image.