since UHD formats cram 4X the number of pixels onto a screen as HD, for screens of the same
size, UHD pixels are ¼ the size of HD pixels; conversely, for pixels of the same size, UHD
screens have 4X the viewing area of HD screens.
The Difference Between HD and UHD for a Viewer
In simplest terms, then, the whole viewing difference between an HD display and a UHD
display comes down to just one point: bigger screens with no loss of visual quality—where
“visual quality” is measured by the single metric of apparent pixel size. It makes no difference
whether you replace your old display with a new UHD display of the same size and move
closer to it; or keep the same viewing distance, but replace your old display with a bigger UHD
display. In both cases, the effect is exactly the same: the screen looms larger in your visual
UHD Provides a More Immersive Viewing Experience
The ability to increase apparent screen size with no loss of visual quality is not everything, but
it is not nothing, either. The apparent size of a screen in our viewing area is a key factor in
what is generally called viewing immersion; indeed, the illusions of virtual reality are created
largely by covering our entire viewing space with a screen.
By this analysis, then, the advantage of UHD over HD is primarily its ability to create a more
immersive viewing experience, by allowing us to get closer to screens of the same size, and
view larger screens at the same distances, with no loss in visual quality. This is presumably a
good thing, at least when we want to be more immersed in what we are viewing. But, like
many good things, UHD has its own trade-offs.
The Cost of the UHD Experience
The most obvious trade-off for UHD is simply the cost quadrupling the number of pixels per
video frame, from about 2 million to about 8 million. As a viewer, you might think that doesn’t
matter, as long as advancing display technology makes new 8-million pixel UHD screens
available in the same price range formerly paid for comparable 2-million pixel HD screens.
Like an iceberg, however, the implications of multiplying pixelsrun far deeper than the visible
surface of a UHD screen. We will turn to that topic in the next part of this series.
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