“…2 (a). Under this inpainting framework, paired training data can be easily obtained by randomly generating masks as in general image inpainting [15,19,22,24,30,32,35,35,37,39,44,45,48,50,51,53,56,59] and extracting edges/contours in the masked regions as surrogate sketches using edge detection algorithms [1,5,6,13,21,25,26,38,43,47,49]. Then the problem can be solved by training an inpainting model to predict the original image given the masked image, mask, and sketch as input.…”