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MoESR: Blind Super-Resolution Using Kernel-Aware Mixture of Experts
Modern deep learning super-resolution approaches have achieved remarkable performance where the low-resolution (LR) input is a degraded high-resolution (HR) image by a fixed known kernel i.e. kernel-specific super-resolution (SR). However, real images often vary in their degradation kernels, thus a single kernel-specific SR approach does not often produce accurate HR results. Recently, degradation-aware networks are introduced to generate blind SR results for unknown kernel conditions. They can restore images for multiple blur kernels, however they have to compromise in quality compared to their kernel-specific counterparts. To address this issue, we propose a novel blind SR method called Mixture of Experts Super-Resolution (MoESR), which uses different experts for different degradation kernels. A broad space of degradation kernels is covered by kernel-specific SR networks (experts). We present an accurate kernel prediction method (gating mechanism) by evaluating the sharpness of images generated by experts. Based on the predicted kernel our most suited expert network is selected for the input image. Finally, we fine-tune the selected network on the test image itself to leverage the advantage of internal learning. Our experimental results on standard synthetic datasets and real images demonstrate that MoESR outperforms state-of-the-art methods both quantitatively and qualitatively. Especially for the challenging x4 SR task, our PSNR improvement of 0.93 dB on the DIV2KRK dataset is substantial.