Depth-Controllable Very Deep Super-Resolution Network

Deep learning techniques not only have surpassed humans in several computer vision tasks, but also have achieved state-of-the-art performance on the super-resolution (SR) task, which enhances the resolution of reconstructed images from the observed low-resolution (LR) images. Very Deep Super-Resolution (VDSR) is a popular architecture with decent performance on the SR task. In general, the deeper the VDSR network, the better the performance. Say, on a computing device with limited computational resources, the SR task must support multiple resolutions or multiple output rates. For this multi-rate SR task, the state-of-the-art architectures require multiple networks with varying depths. However as the number of supported rates increases, so does the number of networks imposing incremental computational burden on the computing device. We propose a depth-controllable network and training principles for the multi-rate SR task. The proposed network is configured as a single network regardless of the number of supported rates. The inverse auxiliary loss and contiguous/progressive skip connections are presented to train the network end-to-end throughout the varying number of layers without biasing the performances of specific depths. With three data sets and three scaling factors, the proposed network is compared to the baseline network VDSR, along with the Super-Resolution Convolutional Neural Network (SRCNN). Our network not only requires a single network at varying rates, but also performs as well as the baseline networks in terms of Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity (SSIM). Our model outperforms the baseline networks when the depth of layers is more than eleven.