32 MACWORLD MARCH 2020
MACUSER REVIEW: SAMSUNG CJ791 ULTRA WIDE QLED DISPLAYabout ten years ago. When vendors
switched from CFL to LED backlighting, the
color spectrum produced by most displays
(OLED excepted) skewed heavily to blue—
the color temperature got very cold and
colors commensurately inaccurate.
LED backlit LCD displays have fought
this phenomenon through various means,
but by far the most effective has been the
quantum dots
like those used
by the CJ791.
Quantum dots
re-emit any light
that shines on
them (lower than
their resonant
frequency) in a
very narrow
range in strict
accordance with
their size (20nm
to 100nm). That means that sized
properly, nearly pure blue, green, and red
are produced, which can then be
combined to produce other pure colors.
Quantum dots are the Q in QLED, and
they make a big difference.PERFORMANCE
With the CJ791, light bleed is a bit of an
issue with dark
backgrounds,
and the contrast
isn’t particularly
good. With a
full-screen black
image, you will
see more of a
dark gray.
Thankfully,
there’s never
really a reason toNote how much more bleed from other colors is present in this typical
LED backlit display.
These are the readings when the CJ791 displays pure blue, green,
and red images. Note that there’s not a lot of any other color present.
Compare with the non-quantum dot readings below.