› An AI image upscaler enlarges a photo and fills in missing detail, rather than simply stretching its pixels.
› That is a fundamental difference: conventional methods calculate new pixels from their neighbours, which softens the image, while AI models predict what a sharper version might look like.
› They can therefore invent details that were never in the photo.
› Here’s what an upscaler can and can’t do, which free online and desktop tools have limits, what paid options cost, and what tends to go wrong with portraits and documents.My test on 24 October 2026: four upscalers on the same imagesThree images were reduced to 512 px: a portrait, a product photo and a menu.