For the issues that the photographic image (PIM) and computer generated images (PRCG) identification scheme have features of poor generality and high dimension in image forensics, an image forensics scheme base on forecast error variance analysis in color filter array (CFA) interpolation is proposed. First, the Fourier spectrum of prediction error variance of CFA interpolation is analyzed, and the PIM and PRCG are distinguished according to whether there is a distinct periodic peak phenomenon. Then, the periodic peak model is analyzed, and the source of PIM is identified according to the peak value features. Finally, experiments have been done on natural images from Columbia University and computer generated image database ADVENT. Experimental results show that the proposed scheme can accurately distinguish between PIM and PRCG, and the recognition rate of the PIM source devices (Canon, Nikon and SONY) reached 93%.