APPPPPPPPPPLLLLLLLLEEEE CCCCOOOORRRREEEEE Facts & figures
Screen res. Colour depth. Pixel density.
What does it all mean to your eyes?> It’s easy to scoff at the original iPhone’s
320x480-pixel display as lo-res, but it had a
higher pixel density than Macs of the time (164 versus
72ppi). Even the iPod managed 102ppi. There’s good
reason you recall both having chunky pixels, though...1 .07 billion
> Even today’s iMac compromises to make
your eyes think it can show 1.07 billion
hues (10 bits per colour channel), aided
by its 218ppi density. Temporal dithering
cycles a pixel between two hues. Spatial
dithering puts two colours next to each
other. Your eyes see these as a blend.1
JUNE 2019 | MACFORMAT | 11
> The Mac started life with 1-bit colour
depth, so each pixel was simply on or off,
meaning it had a truly monochromatic
display. Later this increased to 2-bit
colour, giving four shades. It wasn’t until
1987’s Macintosh II that colour displays
and graphics cards added the ability
to output 256 colours at once.4
2
> The first Mac’s 9in display packed a 512x342-
pixel resolution and 72 pixels per inch. If you
lowered the 13in MacBook Pro’s from 227 to
72ppi yet kept its 2560x1600 resolution, you
would end up with a 42in ‘notebook’.42in
> Traditional ‘true colour’ displays use an 8-bit representation for each of the
red, green and blue colour channels. That gives 256 levels of each channel,
which in turn works out to over 16.7 million possible hues.Over 2x
3
5
> The meaning of ‘Retina display’ varies based on
a device’s typical viewing distance. Take London’s
Piccadilly Lights, for example: if it were flat, the
installation would measure 1,888in diagonally. The
optimal distance of a 4K display that big would be
30.8m. It’s just 35.1cm for a 21.5in iMac on a desk.4
6