| Digital noise appears as a spray of colored
pixels in an image. Although several third-party
plugins can be used in conjunction with Photoshop
to eliminate it, I’ve found it’s actually quite
simple to use Photoshop by itself.
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Use Color Mode
When I increased the intensity of a sky image
with a Curves adjustment layer, I also increased
the noise in the image. The Photoshop essentials
I use for eliminating noise are the Gaussian
Blur filter in conjunction with blending modes
by use of layers or the History palette and
brush. Here, I used the Color blending mode.
- Add a layer above your adjustment layer.
Press Option while choosing Merge Visible
from the Layers palette menu to create a
merged composite.
- Set the layer blending mode to Color.
- Choose Filter > Blur > Gaussian Blur. With
the Gaussian Blur dialog box open, zoom
in and out of the image (Command + or -).
This will help you choose an amount that
eliminates noise but not to the point of too
much desaturation and bleed of colors. For
most images, a Radius between 5–7 pixels
works fine (I chose 7 for the sky).
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Use Fade and Unsharp Mask
The egg image had noise due to shooting at
1600 ISO. In addition to a Gaussian Blur, I used
Fade and Unsharp Mask.
- After applying a Gaussian Blur, choose
Edit > Fade Gaussian Blur, and set the
Mode to Color.
- Eliminate haze and put clarity back into
the image by choosing Filter > Sharpen >
Unsharp Mask. I used 15-85-0 to make the
eggs clearer. I also added a Selective Color
adjustment layer.
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Use the History Brush
Sometimes the noise in an image is distracting
in particular areas. I use this method to selectively
paint away the noise.
- After applying a Gaussian Blur, open the
History palette (Window > Show History).
Choose History Options from the palette
menu and check the Allow Non-Linear
History box.
- In the History palette, click the column for
the Gaussian Blur state; the History Brush
icon will appear.
- Highlight the previous state above the
Gaussian Blur (the name, not the column)
to return the image to its noisy state. It
will be named Duplicate or Open.
- Select the history brush from the Toolbox.
Select a Soft Round brush.
- Change the history brush Mode to Color
in the top menu bar. The Opacity and Flow
should be set to 100%.
- Paint over the noisy areas. Since the history
brush is sourcing the Gaussian Blur state,
you are painting with the blur. Using Color
Mode retains detail but hides the blurriness
while desaturating the colored noise pixels,
making them less noticeable.
TIP: Try substituting Filter > Noise > Median
for the Gaussian Blur. Also, Filter > Noise
Despeckle is helpful for minimal specks and
moiré. When all else fails, choose Image > Size
and create a few upsample to downsample
versions. The interpolation of Bicubic tends to
soften images when resampling while helping
to reduce the visible appearance of noise.
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Shan Canfield is an Adobe Certified Expert, instructor,
designer, photographer, digital
artist and retoucher.
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