Upscaling maps an image to a greater pixel resolution, often so a lower-resolution programme can fill a higher-resolution screen. The processing estimates or interpolates additional picture information. It can improve presentation, but it cannot recover every detail absent from the original recording, encoding or transmission that supplied the smaller image.
A practical example
A television can enlarge a 1080-line programme to fit its 4K panel. A good result may look tidy at a normal viewing distance, yet it remains different from a source that originally captured and preserved more genuine fine detail.
A common misunderstanding
Do not treat an output setting marked 4K as evidence that all viewed programmes originate in 4K. The device may simply be scaling every source to one chosen output mode.
Related terms
Stable technical definition. Editorial approach