Commercial Integrator June 2022 - 8

Brought to you with the support of
AV BRAINS & BRAWN
A New Look at Pixels and LED
When we define our terms and understand what, exactly, our eyes are processing, we can
make better technology decisions and deliver enhanced client outcomes.
By Alan C. Brawn and Jonathan Brawn
AS OUR READERS KNOW, we tend to write
about things that need further explanation
than what appears on the surface. In this
instance, the " surface " to which we're
referring is the surface of a flatpanel display.
The good news is that you don't have to
understand the nature of the liquid crystal
material or the active layers of OLED or LED
(although some of us AV geeks do). So, rest
easy! But there is something that must be
deeply understood. Drum roll please....
We're talking about pixels and how they
relate to the human eye and visual acuity.
Our perception of pixels - both individually
and collectively - forms our impression of
an image. Please permit us to explain the
relevance of visual acuity, while also tying in
the unique nature of direct-view LED (dvLED).
I like how Technopedia defines a pixel, so
that is where we'll start. Its definition is this:
" A pixel is also known as a picture element
(pix = picture, el = element). A pixel is the
smallest unit of a digital image or graphic that
can be displayed and represented on a digital
display device. A pixel is the basic logical
unit in digital graphics. Pixels are combined
to form a complete image, video, text or any
visible thing on a computer display. "
Images Built from Pixels
We all know that in the world of displays,
images are made up of a matrix of discrete
pixels; they combine collectively to create
what we see onscreen. In projection, the
LCD, DLP or LCoS imagers (or chips, as we
commonly call them) are each made up of
pixels. The imager receives a video signal
and transfers it through a series of optics,
and, when combined with a light source,
it goes through an exit lens that magnifies
the image onto a screen. In this case,
you then see the pixels on the projection
screen or surface.
In projection, there are imagers with varying
resolutions. This refers to the number
of pixels both horizontal and vertical. The
8
Commercial Integrator JUNE 2022
be viewing the display far enough away
from the screen not to see pixels? If you're
too close to the screen or if the screen is
simply too large for its resolution, you may
see individual pixels. This is the root of the
full-HD versus 4K versus 8K conversation.
In the world of displays, images are
made up of a matrix of discrete pixels.
They combine collectively to create
what we see onscreen.
resolution typically ranges from a low of
1024x768 (XGA), to 1920x1080 (full HD),
to 3840x2160 (4K or ultra-HD) or the DCI
spec for digital cinema at 4096x2160 pixels.
(Yes, we know 8K is out there, but not
in quantity for commercial applications.) In
simple terms, the larger the image will be,
the greater the need will be for the display
to have more pixels. This is to avoid the
human eye being distracted by them. For
example, an 80-inch diagonal screen at
1920x1080 might look great; however, if
you double that size to 160 inches diagonal,
you might see individual pixels at the
same viewing distance.
In direct-view displays, the images are
created by the viewer looking directly
at the display device, rather than using
optics to project and a surface to reflect
light. Quite literally, what you see is what
you get. You buy a fixed-size screen with a
fixed number of pixels. The most common
commercial AV flatpanel resolutions today
are 1920x1080 (full HD) and 3840x2160
(4K or ultra-HD). (Again, yes, we know
there is 8K, but it's even less commonplace
in commercial applications than 8K
projection is.) Our considerations here
boil down to image size, viewing distance
and pixel density. How many pixels are
packed into each inch of screen? Will you
Pixel Density
So, we understand resolution. But, with
dvLED, we also must deal with pixel pitch.
What is the difference between the two,
and why do we hear so much about pixel
pitch? Let's begin the conversation by
discussing pixel density.
Resolution is inherently tied to a display's
pixel density. It's measured by counting all
the pixels that run horizontally and vertically
across a screen. For example, if a screen
has a 2560x1440 resolution, that means it
has 2560 pixels in every row running horizontally
across the screen and 1440 pixels
in each vertical row. From there, we can
calculate the pixel density, based on the
physical size of the screen. A large screen
with a specific resolution has a lower pixel
density than a physically smaller screen
with the same resolution. That is because
the large screen has the same number
of pixels spread out over a larger surface
area. Thus, they are simply bigger. The
pixels per inch (PPI) will indicate how close
you can get to a given display before you
can discern the individual pixels.
With dvLED displays coming to the fore
in many applications, the idea of pixel density
becomes even more important. This
brings a new set of parameters and considerations
to the table. In dvLED, the size and
aspect ratios of the displays are (almost)
unlimited, and a variety of pixel pitches can
be applied based on cost and use case.
Let's explore how this concept applies to
dvLED in the following simple, real-world
application: We need a dvLED display to
replace a projector, where the project calls
for a 16:9 aspect ratio and 1920x1080 (full
commercialintegrator.com
GORODENKOFF/STOCK.ADOBE.COM
http://www.commercialintegrator.com
Commercial Integrator June 2022

Table of Contents for the Digital Edition of Commercial Integrator June 2022
