Stereo image pairs can be used to improve the performance of super-resolution (SR) since additional information is provided from a second viewpoint. However, it is challenging to incorporate this information for SR since disparities between stereo images vary significantly. In this paper, we propose a parallax-attention stereo superresolution network (PASSRnet) to integrate the information from a stereo image pair for SR. Specifically, we introduce a parallax-attention mechanism with a global receptive field along the epipolar line to handle different stereo images with large disparity variations. We also propose a new and the largest dataset for stereo image SR (namely, Flickr1024). Extensive experiments demonstrate that the parallax-attention mechanism can capture correspondence between stereo images to improve SR performance with a small computational and memory cost. Comparative results show that our PASSRnet achieves the state-of-the-art performance on the Middlebury, KITTI 2012 and KITTI 2015 datasets.
@cite_38: Light-field cameras can capture spatial and angular information of light with a single exposure, but they suffer from low spatial resolution that limits their performance in practical use. Superresolution (SR) methods have been used to improve spatial resolution of light-field images, but most of them do not take full advantages of the particular structure of the light field. In this letter, we present an SR method to obtain light-field images with high quality and geometric consistency via a combined deep convolutional neural networks (CNNs) framework. The spatial resolution of subaperture images is enhanced separately by a single-image superresolution deep CNN. Then, an epipolar plane image enhancement deep CNN is proposed to restore the geometric consistency of these images. Experimental results show that our method achieves the state-of-the-art performance on both quantitative and qualitative evaluations.
@cite_16: The low spatial resolution of light-field image poses significant difficulties in exploiting its advantage. To mitigate the dependency of accurate depth or disparity information as priors for light-field image super-resolution, we propose an implicitly multi-scale fusion scheme to accumulate contextual information from multiple scales for super-resolution reconstruction. The implicitly multi-scale fusion scheme is then incorporated into bidirectional recurrent convolutional neural network, which aims to iteratively model spatial relations between horizontally or vertically adjacent sub-aperture images of light-field data. Within the network, the recurrent convolutions are modified to be more effective and flexible in modeling the spatial correlations between neighboring views. A horizontal sub-network and a vertical sub-network of the same network structure are ensembled for final outputs via stacked generalization. Experimental results on synthetic and real-world data sets demonstrate that the proposed method outperforms other state-of-the-art methods by a large margin in peak signal-to-noise ratio and gray-scale structural similarity indexes, which also achieves superior quality for human visual systems. Furthermore, the proposed method can enhance the performance of light field applications such as depth estimation.
@cite_12: 
Light-filed imaging can capture additional angular information of light at the cost of spatial resolution. To enhance spatial resolution, Yoon @cite_12 introduced black the first light-field convolutional neural network (LFCNN). Yuan @cite_38 proposed a CNN framework with a single image SR module and an epipolar plane image enhancement module. To model the correspondence between images of adjacent sub-apertures, Wang @cite_16 developed a bidirectional recurrent CNN. Their network uses an implicit multi-scale feature fusion scheme to accumulate contextual information for SR. Note that, these methods are specifically proposed for light-field imaging with short baselines. Since stereo imaging usually has a much larger baseline than light-field imaging, these methods are unsuitable for stereo image SR.