Why You Should Calibrate Your Screens (And How This
Little Chart Helps)
Ever wondered why a photo looks perfect on your phone but
flat and washed out on your TV or a print? It is not you. It is your screens.
Even the best cameras, monitors and printers cannot capture or display the full
range of light and colour that your eyes can see. That is where a simple
calibration card comes in, and once you understand how to keep your equipment
acceptably accurate.
Photographers talk about dynamic range, the span of light a
device can capture, measured in stops. Each stop doubles the amount of
light involved. Your eyes can handle around 15 stops. A good modern camera
manages 9 to 11. Most TVs and monitors only reach 7 to 9, and even quality
printers top out around 6.5.
That gap matters. When a device cannot handle the full
range, it clips the extremes. Dark tones near black collapse into pure black.
Bright highlights blow out into pure white. Detail and colour simply disappear
at both ends.
Colour is its own puzzle, it doesn’t really exist as
something physical, and there are two divergent interpretations of what creates
it. How a device captures and reproduces colour is pure physics and maths of
energy and light. How your brain perceives colour is much more personal, shaped
by cognitive psychology and the lighting around you. Neither view is more
"correct" than the other. The calibration chart will not give you
laboratory precision, but it will nudge your average colour rendering and tonal
contrast in the right direction.
Step One: Calibrate the Input (Your Camera or Phone)
Tonal calibration, getting the brightness and darkness
levels right, is the single most useful adjustment you can make for realistic
photos.
Look at the calibration chart and you will see a grey scale
gradient running from black to white, with small grey rectangles down each
side. On the right, the rectangles start light grey and get progressively
lighter toward an almost white target. On the left, they start darker and step
down toward a very dark target. Each little step represents a 2 percent shift
in light intensity.
Here is the trick: point your camera or phone at the chart
and check how many of those rectangles you can actually distinguish. You will
probably lose a few, especially near the very dark or very light end. That is
completely normal. Digital sensors simply cannot match your eyes' range, and
cameras are designed to expose for an average middle grey tone anyway, so they will
usually “clip” the extreme tones.
Start with your camera on an automatic exposure mode (A, P,
or the green auto setting on a DSLR or mirrorless camera, or the default mode
on your phone). Manual exposure is not necessary here.
Check the result somewhere you can actually see the screen
properly. Camera and phone screens are notoriously hard to read in bright
daylight, so review indoors or in shade.
If you can only spot a few rectangles on the dark side, the
chart probably needs more light. If you cannot add light, try adjusting the
exposure value (EV) on your camera or phone instead.
Advanced camera calibration (colour accuracy, white balance,
lens distortion, sharpness) varies wildly between brands and models, so this
card will not replace a proper colour profiling system. What it can do is flag
obvious problems, like a consistent colour cast, or tonal issues worth
investigating further.
Step Two: Calibrate the Output (Your Screens)
Now views a photo of the ca on your monitor, TV, phone or
projector. This is where brightness and contrast come in, usually tucked inside
a picture or display settings menu, accessed through a settings button or
remote.
Start with brightness. Push it up and the screen gets
lighter, revealing more rectangles on the dark side. Pull it down and you will
see more detail in the light rectangles instead. The goal is a balance where
you can see a good number of steps on both sides.
Next comes contrast. This stretches or compresses the range
of visible tones. Getting it right is a bit of a balancing act between contrast
and brightness. If you can see plenty of rectangles on one side but hardly any
on the other, nudge the contrast up slightly, then pull brightness back to
rebalance.
A quiet warning here: if you regularly use your screen in a
bright room with strong light behind you, chances are your contrast is already
cranked to maximum, which clips both ends of the tonal range. If that sounds
like you, reset contrast to the middle, adjust brightness first, then slowly
bring contrast back up while rebalancing.
Screen technology has changed a lot over the decades, from
old cathode ray tubes to today's LED and LCD panels, and every manufacturer
implements these settings a little differently. Materials also degrade over
time, which is worth remembering if your screen seems duller than it used to
be. When in doubt, the factory reset option is usually a safe, well calibrated
starting point.
Step Three: Get Your Colours Right
Once tone is sorted, it is time for colour. Look for
settings labelled colour, tint, colour temperature, hue, saturation or
intensity, though the exact wording and
what bit changes depends on your device.
Saturation is often cranked up by default to compensate for
ambient light, so check the row of coloured dots on the card. They should look
natural sitting against the mid grey background, not artificially intense.
Many screens also offer picture modes such as vivid,
natural, cinema, standard or eco. These bundle together saturation, brightness
and contrast settings, so cycling through them is often the fastest way to find
something that suits your eyes, though be aware they can override the careful
brightness and contrast work you just did.
The chart itself has a colour temperature section running
from warm reds, oranges and yellows through to cool blues and violets, sitting
on a clean white background. If that background does not look properly white,
you likely have a colour cast issue.
Small reference squares next to this section are arranged in
5 percent increments of colour strength. The top row handles colour
temperature, from yellow through to blue purple. The bottom row handles “tint”,
from magenta through to green. The middle row, goes from a red to a cyan .
To use them, simply check which square looks whitest against
the background. If the background leans slightly green, for instance, a square
on the magenta side will probably look closer to true white. That tells you
which direction to nudge your tint control.
One last thing worth remembering: your room's ambient
lighting will influence how you judge all of this. Do not calibrate for magenta
while sitting in a room bathed in green light. Match your adjustments to the
conditions you will normally be viewing in, and you will end up with a screen
that shows your photos the way they are meant to be seen.
You should now have better screens to judge your images, that may be photographing your art, a portrait or to judge your results as you edit or
modify your photographs with filters and app.
