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When I take photos of birds and wildlife, I
often use sensitivities between 400 and
3200. Even though the recent cameras are
pretty good at high ISO, there is always
some noise, in particular in the out of
focus areas. It is not a problem: with
Photoshop, it is quite easy to reduce the
noise, and I've made excellent print even
from photos taken at very high
sensitivities. Remember that while it is
possible to reduce the noise, it is not
possible to correct the blur created by an
excessively slow shutter speed: thus, don't
hesitate to use high ISO when it is
necessary.
Noise reduction
with Photoshop
Photoshop has a powerful noise reduction
function that reduces effectively the
"grain", keeping as much detail as possible.
To open the NR window, click on the menu
Filter > Noise > Reduce Noise. You can
choose between a "Basic" and an "Advanced"
interface; I always use the Basic option,
since it is easier to use and faster, and it
has all the controls that I need. On the
left side of the window there is a large
preview; in the right side there are four
sliders.
Strength and Preserve Detail work
together to determine the intensity of
luminance noise reduction. I recommend to
set both of them on a high value (I often
use Strength 10 and Preserve Detail 90%).
Remember that reducing noise also reduces
detail: don't use an excessive reduction!
Reduce Color Noise determine the
intensity of color noise reduction. The
color noise is the most annoying type of
noise, but it can be reduced very
effectively without loss of detail; the only
downside is a diminution of color accuracy
(the colors become less vivid and
saturated). Depending by the image, I
suggest to use a value between 15 and 60.
Sharpen Details allows to apply some
sharpening to the image; I suggest to avoid
it (set the slider on 0%); it is better to
use the much more advanced Smart Sharpen.
The checkbox Reduce JPEG Artifacts is useful
only with images that had been saved with an
excessive JPEG compression; since I always
use RAW, I leave this checkbox deselected.
The Reduce Noise window is an useful
tool, but you should learn to use it
properly. A common error is to apply an
excessive noise reduction; the resulting
image is noise free but it has lost a lot of
detail and it has a "plastic", artificial
look. I am quite "conservative" with noise
reduction; it is better to leave a little of
noise that to get an over processed image.
Noise reduction
workflow
Even though it is possible to apply to noise
reduction on the entire photo, I often
prefer to use a more advanced technique to
preserve the detail of the subject and to
get a cleaner image. With the Layer Mask, it
is possible to apply the noise reduction
only on the background, or to apply
different levels of noise reduction on the
subject and on the background.
The image 2 is a crop from the photo 1,
without any adjustment other than the basic
enhancements of brightness and contrast. The
photo has been taken at ISO 1600 so there is
some noise, in particular in the out of
focus background.
In crop 3, I
applied a slight noise reduction on the
entire image (Strength 10, Preserve Detail
95%, Reduce Color Noise 25%). With these
settings, the photo looks relatively good
- the color noise has disappeared, but there
is still some luminance noise. The colors
looks slightly less saturate than in
previous crop, due to the color noise
reduction, but the difference is very slight
and the detail is still excellent. It would
be possible to print this photo with
excellent results, the noise would be barely
visible even in large prints. That said, if
you want a 100% noise-free file, it is
possible to enhance even more the photo,
with a selective noise reduction on
background.
The first step is to
duplicate the background layer
(Layer>Duplicate Layer), to create a copy of
the image. Now, you have the original image,
in the first layer (Layer 1), that remains
untouched, while you can apply a strong
noise reduction on the copy (Layer 1 Copy).
To remove completely the noise, apply the
Reduce Noise filter with very aggressive
settings (Strength 10, Preserve Detail 0%,
Reduce Color Noise 20%) to the Layer 1 Copy;
you can apply NR even two or three times,
until the photo is completely noise free.
The photo becomes very clean, noise-free,
but of course the detail is completely
smudged: to get a good result, you have to
apply such strong noise reduction only on
the out of focus areas, as the background.
Apply the Layer Mask (Layer>Layer Mask>Hide
All) to Layer 1 Copy, and click on the Brush
Tool. The Layer Mask is one of the most
powerful and versatile tools of Photoshop -
if you don't know well what it is and how it
works, I recommend to read the article
"Layers and Layer Mask".
Now, you
have to "paint" on the areas where you want
to apply the strong noise reduction.
Usually, I select a relatively small brush
(Master Diameter 50 or 60px, Hardness 70%)
and I magnify the photo to 100% to follow
precisely the borders of the subject.
Remember than you don't have to touch the
borders with the brush - otherwise they
becomes a bit fuzzy. It is always better to
leave few pixels between the border of the
subject the the brush. In some images, you
can do it quicker by using the Magic Wand to
do an approximate selection of the
background.
When I have finished the
fine adjustments, I select a larger brush to
apply the noise reduction on the rest of the
background, and finally I flatten the layers
with Layer>Flatten image. The crop 5 is
taken from the final image: the subject has
kept its detail, while the background is
nicely smooth and noise-free. This workflow
takes a bit of time, so I recommend to use
it only on your best images; if you have to
edit a large number of photos you can get
quite good results even with a moderate
noise reduction applied on the entire image.
Do you have
comments or questions?
If you have comments or questions about
this article, feel free to ask in the
Juza
Nature Photography Discussion Forum!
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