The technical term is “inpainting” (https://en.wikipedia.org/wiki/Inpainting https://en.wikipedia.org/wiki/Inpainting), so “inpainting algorithms” will give you

The technical term is “inpainting” (https://en.wikipedia.org/wiki/Inpainting https://en.wikipedia.org/wiki/Inpainting), so “inpainting algorithms” will give you papers on various ways to do it. In general, diffusion isn’t a good way to do it, as diffusion fills in the missing hole with data with fewer small details than the surrounding area. Modern smartphones are fast enough for implementations.