Single-image super-resolution (SISR), which maps a low-resolution observation to a high-resolution image, has been extensively utilized in various computer vision applications. With the advent of convolutional neural networks (CNNs), numerous algorithms have emerged that achieve state-of-the-art results. However, the main drawback of CNN is the negligence in the interrelationship between the RGB color channel. This negligence further reduces crucial structural information of color and provides a non-optimal representation of color images. Furthermore, most of these CNN-based methods contain millions of parameters and layers, limiting the practical applications. To overcome these drawbacks, an endto- end trainable single image super-resolution method – Quaternion-based Image Super-Resolution network (QSRNet) that takes advantage of the quaternion theory is proposed in this paper. QSRNet aims at maintaining the local and global interrelationship between the channels and produces high-resolution images with approximately 4x fewer parameters when compared to standard CNNs. Extensive computer experimentations were conducted on publicly available benchmarking thermal datasets, including DIV2K, Flickr2K, Set5, Set14, BSD100, Urban100, and UEC100, to demonstrate the effectiveness of the proposed QSRNet compared to traditional CNNs.
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