Prior and Prediction Inverse Kernel Transformer for Single Image Defocus Deblurring

Defocus blur, due to spatially-varying sizes and shapes, is hard to remove. Existing methods either are unable to effectively handle irregular defocus blur or fail to generalize well on other datasets. In this work, we propose a divide-andconquer approach to tackling this issue, which gives rise to a novel end-to-end deep learning method, called prior-andprediction inverse kernel transformer (P 2 IKT), for single image defocus deblurring. Since most defocus blur can be approximated as Gaussian blur or its variants, we construct an inverse Gaussian kernel module in our method to enhance its generalization ability. At the same time, an inverse kernel prediction module is introduced in order to flexibly address the irregular blur that cannot be approximated by Gaussian blur. We further design a scale recurrent transformer, which estimates mixing coefficients for adaptively combining the results from the two modules and runs the scale recurrent "coarse-to-fine" procedure for progressive defocus deblurring. Extensive experimental results demonstrate that our P 2 IKT outperforms previous methods in terms of PSNR on multiple defocus deblurring datasets.