CGAN-IRB: A Novel Data Augmentation Method for Apple Leaf Diseases

Abstract

At present, the identification of apple leaf diseases plays an important role in controlling apple leaf diseases and improving apple yield. CNNs(Convolutional Neural Networks) have been widely used in apple leaf diseases identification, but the training of the CNNs requires a large number of images. The lack of images would make the CNNs hard to generalize. Thus the CNNs are unable to recognize new disease images. Focusing on this problem, this paper proposes a new model named CGAN-IRB(Conditional Generative Adversarial Network with the Improved Residual Block) for data augmentation. Firstly, various improvements have been made based on CGAN to generate high-quality, robust, and specific-category images of apple leaf diseases. Among which the embedding of the residual block has been found to significantly improve the model performance. Then the interpolation algorithm is used instead of deconvolution to increase the image size. Finally, the TTUR(Two-Timescale Update Rule) training strategy is employed and all the convolutional layers of the network are spectrally normalized to stabilize the training of the network. The performance of CGAN-IRB was tested both on image generation and classification tasks. Experiment results show that the images generated by the network possess high quality and robust features, pro-viding a novel solution for the data augmentation of apple leaf diseases. The new GAN-based data augmentation method leads to significant improvements in the classification accuracy of CNNs. In the case of all tested CNNs, the classification accuracy improvements are 11.75% and 2.17% on average over non-augmented and traditional-augmented, respectively. Among them, the classification accuracy of GoogLeNet V2 and ShuffleNet V2 is 99.34% and 99.67%, respectively. The data augmentation approach proposed in this paper can be used more widely in the field of disease identification, solving the problem of insufficient data sets, and can be extended to related fields where data sets are difficult to obtain.