A Rotation-Invariant Convolutional Neural Network for Image Enhancement Forensics

Many proposed complex convolutional neural network (CNN) models in image forensics are with a large number of parameters, requiring a huge number of training data and having the risk of being overfitting. Considering the desired rotation invariance in the detection of some specific image manipulations, i.e., image enhancement, we propose employing convolutional filters with an isotropic architecture in the CNN model which can significantly reduce the required number of CNN parameters. With the same weights in symmetric positions, the proposed filter can extract rotation-invariant features for image enhancement forensics. Experimental results show that the proposed rotation-invariant CNN models with much less parameters can achieve much better performance, e.g., yielding more than 13% improvement in terms of detection accuracy in Gamma correction forensics. It also achieves significantly better generalization performances on different databases and better robustness against JPEG compression when compared with the popular BayarNet in [16].