104 Macworld • March 2021FEATURE
This image from Vizio illustrates the concept of local dimming LED arrays.That’s what we have in all our iPads,
MacBooks and iMacs today.
It can get complicated, but in
short, there’s a backlight (usually
white), with an LCD layer on top of it.
The purpose of the LCDs is to block
a controlled amount of light from
the backlight. On top of the LCDs
are colour filters that turn the light
red, green, or blue. That’s the basic
structure, but modern LCDs have
other layers like polarizers, anti-glare
coatings, and so on. A big white light,
covered by a bunch of tiny LCDs
(three for each pixel) to block or let
through various amounts of light, and
a colour filter to turn the light red,
green or blue.
What Mini LED technology does is
replace that big backlight with a grid
of lots of tiny little backlights.
I’m glossing over the finer points.
There are lots of exceptions. In TVs,for example, larger LED backlight
arrays with what is called ‘local
dimming’ are common, and even Mini
LED TVs are already on the market
from brands like TCL. Apple’s Pro
Display XDR is very nearly a Mini LED
display, with 576 backlight LEDs that
are individually controlled (a typical
Mini LED display of that size would
have perhaps a few thousand).
So that’s Mini LED in a nutshell:
kind of like the Pro Display XDR,
but with many more, smaller, LED
backlights.PRECISE LOCAL
DIMMING AND HDR
What does a backlight array of
thousands of tiny LEDs do for you,
exactly? Well, in a traditional LCD
you may have one backlight lighting
up the entire display in a uniform
fashion. It has to be as bright as the104 Macworld • March 2021FEATURE
This image from Vizio illustrates the concept of local dimming LED arrays.That’s what we have in all our iPads,
MacBooks and iMacs today.
It can get complicated, but in
short, there’s a backlight (usually
white), with an LCD layer on top of it.
The purpose of the LCDs is to block
a controlled amount of light from
the backlight. On top of the LCDs
are colour filters that turn the light
red, green, or blue. That’s the basic
structure, but modern LCDs have
other layers like polarizers, anti-glare
coatings, and so on. A big white light,
covered by a bunch of tiny LCDs
(three for each pixel) to block or let
through various amounts of light, and
a colour filter to turn the light red,
green or blue.
What Mini LED technology does is
replace that big backlight with a grid
of lots of tiny little backlights.
I’m glossing over the finer points.
There are lots of exceptions. In TVs,for example, larger LED backlight
arrays with what is called ‘local
dimming’ are common, and even Mini
LED TVs are already on the market
from brands like TCL. Apple’s Pro
Display XDR is very nearly a Mini LED
display, with 576 backlight LEDs that
are individually controlled (a typical
Mini LED display of that size would
have perhaps a few thousand).
So that’s Mini LED in a nutshell:
kind of like the Pro Display XDR,
but with many more, smaller, LED
backlights.PRECISE LOCAL
DIMMING AND HDR
What does a backlight array of
thousands of tiny LEDs do for you,
exactly? Well, in a traditional LCD
you may have one backlight lighting
up the entire display in a uniform
fashion. It has to be as bright as the