54 DIGITAL CAMERA^ OCTOBER 2019 http://www.digitalcameraworld.com
CAMERA COLLEGEcreated. Adjustments are made to
the white balance, gamma curve and
sharpness, colour and contrast, before
the image is temporarily stored in the
camera’s buffer memory and, from
there, written to the memory card.
If you shoot a raw file, this digital
information is stored in a file alongside the
image data, allowing you to select different
processing treatments when you open the
file in raw software; if you shoot a JPEG, the
digital processing effects are applied to the
image before it is written to the memory
card – and there’s no going back later.When it comes to the processing side of
things, you can leave the camera to do
everything or you can make adjustments
manually. White balance, noise reduction
and lens corrections each get their own
dedicated section in the camera’s menu
or control screen, but rather than picture
processing options such as sharpening,
saturation and contrast being listed
individually, they are typically bundled
together as one-click picture presets.
Camera manufacturers have adopted
different brand names for these presets.
In the Canon EOS universe, they’reSharpening, saturation
and contrast are usually
bundled together in
one-click picture presets
ȒȸƬȒǼȒɖȸȵȸȒˡǼƺɀThat’s a moiré!
Watch out for distracting artifacts in areas of fine detail
Subjects that have fine,
grid-like details near the
resolution limit of the grid-like
pattern of photosites on the
sensor can create problems
during demosaicing. The most
common artifact is what’s
known as ‘moiré’, which
manifests itself as stripes or
false colours across the area
of fine detail. You can often
see this effect if you magnify
an area of tightly knit fabric,
such as someone’s clothing.
Other fine, repetitive patterns
also show this undesirable
effect – if there’s a TV, phone
or camera screen in your
photo, look out for it there.
To combat this, many
image sensors in cameras are
covered by an ‘anti-aliasing
filter’ or ‘optical low-pass
filter’. This softens fine details
that could prove problematic,
with the softening effect being
counteracted by sharpening
processes in the camera or
later on a computer (although
it doesn’t always eradicate
moiré). Some cameras,
including the Nikon D850
shown on the previous page,
have the anti-aliasing filter
removed in order to produce
slightly better resolution,
but it may be necessary
to remove moiré effects
later using software.AS SHOTMOIRÉ REDUCTIONIf you haven’t noticed moiré
before, try taking a shot of
a camera bag. You’ll need to
magnify the image to be able
to see the striping effect, which
often appears to move as you
zoom in and out of the shot.You can use an Adjustment
Brush loaded with Moiré
Reduction in Lightroom,
Camera Raw or other raw
software to reduce the effect.
A strong reduction setting may
also strip away some of the
underlying image colour too.Oil be back Moiré typically show its ugly face as an oily,
rainbow-like sheen and zebra stripes across fine-textured fabric.Colour-blind You can open a JPEG in raw editing software
in order to reduce moiré, but you may still be left with
the zebra pattern.