Converting older video footage to 4K is increasingly tempting as 4K OLED displays become standard, but the process involves significant technical limitations that anyone attempting it should understand. Upscaling software cannot recover detail that was never captured in the original recording; instead, it uses interpolation to estimate and generate the additional pixels needed, which can leave footage looking softer, smoother or unnaturally processed if sharpening and noise reduction are not carefully balanced.

Moving from 1080p to 4K requires four times as many pixels overall, and the quality of the result depends heavily on the original source material rather than the conversion process itself. The article cites the HD restoration of Star Trek: The Next Generation as an example of doing this well: CBS commissioned the 2011 project using the show's original 35mm film negatives, equivalent to roughly 20 megapixels of detail, across 25,000 reels of film stock. The remaster of all seven seasons took over three years and reportedly cost more than $12 million (USD), but succeeded because the source material contained far more detail than the original broadcasts. By contrast, converting content whose best available source is already low-resolution offers no such advantage, since all the "extra" pixels must be guessed.