Background Medical datasets, especially medical images, are often imbalanced due to the different incidences of various diseases. To address this problem, many methods have been proposed to synthesize medical images using generative adversarial networks (GANs) to enlarge training datasets for facilitating medical image analysis. For instance, conventional methods such as image-to-image translation techniques are used to synthesize fundus images with their respective vessel trees in the field of fundus image. Methods In order to improve the image quality and details of the synthetic images, three key aspects of the pipeline are mainly elaborated: the input mask, architecture of GANs, and the resolution of paired images. We propose a new preprocessing pipeline named multiple-channels-multiple-landmarks (MCML), aiming to synthesize color fundus images from a combination of vessel tree, optic disc, and optic cup images. We compared both single vessel mask input and MCML mask input on two public fundus image datasets (DRIVE and DRISHTI-GS) with different kinds of Pix2pix and Cycle-GAN architectures. A new Pix2pix structure with ResU-net generator is also designed, which has been compared with the other models. Results and conclusion As shown in the results, the proposed MCML method outperforms the single vessel-based methods for each architecture of GANs. Furthermore, we find that our Pix2pix model with ResU-net generator achieves superior PSNR and SSIM performance than the other GANs. High-resolution paired images are also beneficial for improving the performance of each GAN in this work. Finally, a Pix2pix network with ResU-net generator using MCML and high-resolution paired images are able to generate good and realistic fundus images in this work, indicating that our MCML method has great potential in the field of glaucoma computer-aided diagnosis based on fundus image.

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Thangka is an important part of Tibetan culture, and the classification of Thangka image is one of the basic works of Thangka research. DenseNet(Densely connected convolutional networks) has achieved a very good effect in the field of image classification. Considering that the DenseNet adopts ReLU function which loses the negative feature of the image in the feature propagation process, this paper proposed an improved DenseNet, called L-DenseNet that Leaky ReLU replaces ReLU function to increase the negative feature of propagation. In order to solve the problem of insufficient Thangka image sample, we adopted the method of based fine-tuned network. Experimental results show that L-DenseNet obtains an outstanding performance, which improves 1.1% performance compared with DenseNet. Compared with other CNNs, such as VGG16, ResNet50 and InceptionV3, L-DenseNet obtains state-of-the-art performance in the classification of Thangka image.