Yeah, they could be running a sharpening algorithm. Normally you have something between nearest-neighbor resampling and a smooth gradient. But you can plug any

Yeah, they could be running a sharpening algorithm. Normally you have something between nearest-neighbor resampling and a smooth gradient. But you can plug any function in there if you think it looks good. Bicubic makes nicer smooth areas, sinc can preserve sharp edges. But you can't add information to an image. It's all basically guessing which transitions between pixel values should be smooth and which should be sharp. It's possible to oversharpen an image and generate extra lines out of thin air. (I don't think pinch-to-zoom adds sharpening, but it's something that could use an expert to double check.)