“…These LR-HR patch pairs are cropped from a database composed of LR-HR image pairs. Many learning algorithms have been proposed to learn the mapping models, including dictionary learning [17, 18, 22, 40, 41, 46, 56, 58-60, 65, 66, 70, 76], regression [11,47,48,58,59,64], decision tree [24,62], random forest [23,25,53] and convolutional neural network (CNN) [13,14,33,34,36,37,52,57]. Linear regression models [31] have higher prediction speed than non-linear regressions models.…”