From the article - "Since the linear box filter is a deterministic algorithm, pizelizing the same values will always result in the same pixelated block." The a

From the article - "Since the linear box filter is a deterministic algorithm, pizelizing the same values will always result in the same pixelated block." The author used this property to create the de-pixelizing algorithm. A neural network could do it, but it would be overkill.