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REVIEW | CREATIVITY
PHOTOSHOP CS4 > A GREAT TOOL FOR HIGH DYNAMIC
RANGE IMAGING
Sometimes it takes more than one
photograph to create that perfect image.
High dynamic range imaging (HDR or
HDRI) has increasingly been used to
improve the apparent dynamic range of
digital photographs, or make the photo
look closer to what you see. And
Photoshop CS4 offers detailed tools to
create high dynamic range photos.
What is HDR? HDR is a process for
combining several images taken at
different exposures into a single image
that accurately represent the wide light
intensity range perceived by the human
eye. The intent of HDR is to accurately
represent the wide range of light and
shadows found in real scenes and
captured in digital photos.
For example, if you take a picture of a
scene in bright sunlight (with the
exposure based on bright areas) the
shadows may not have any detail. Take
the same picture exposed to capture
details in the shadows, and the highlights
will be over exposed. Your camera sensor
is capable of only capturing a certain
dynamic range (the difference between
bright and dark areas).
Expensive cameras have a wider dynamic
range than lesser expensive cameras.
Nikon's D3, a professional single lens
reflex (SLR) camera, has a dynamic range
of approximately 12.2, whereas Nikon's
top-of-the-line point and shoot camera,
the Coolpix 6000, has a dynamic range
of 10.2 (based on testing by DxO Labs
. Less expensive digital
SLR cameras will have smaller dynamic
ranges. In comparison to all these
cameras, your eye has a wide dynamic
range of about 24. With current
technology, even the most expensive
camera will not have the visual dynamic
range of the human eye.
How does a photographer overcome their
equipment limitations? One option is to
pick scenes where the dynamic range is
less than the camera's sensors. A second
option is to take several images at
different exposures and apply the high
dynamic range tools provided in Adobe
Photoshop CS4.
Photoshop CS4 includes a "Merge to HDR"
tool [File > Automate > Merge to HDR].
This feature permits the user to select
several photos, which can be combined
into an HDR image. After selecting this
tool, a dialog window opens for the user
to select the source files for the HDR
image. Once the source images are
selected, click "OK". Photoshop CS4 will
automatically align the selected images
and then process these images in to a 32-
bit HDR preview image. The preview
window permits the user to make some
picture adjustments before final
processing. Click "OK" and the HDR
image is displayed in Photoshop CS4.
A second option is using a combination of
two layer tools: Auto-Align Layers and
Auto-Blend Layers. To apply these
features, first create a Photoshop
document where each photo that you
want to combine is a layer in the
document. Unless the photos were taken
on a tripod, you will want to first apply the
Auto-Align Layers [Edit > Auto-Align
Layers]. This tool aligns the layers based
on the content in each layer, and is a
great tool for still images. However, as
expected, don't select slightly moving
objects as your subject, like floating boats
or moving trees in the wind, since the
images won't align perfectly.
Next, select the Auto-Blend Layers [Edit >
Auto-Blend Layers] tool and a dialog
window is displayed. In this window select
the Stack Images Blend Method followed
by clicking on Seamless Tones and Colors.
Click "OK" and Photoshop will blend the
layers based on the image content.
Further image adjustments may be made
using the entire set of tools.
Both options allow greater enhancement
of your photograph, however the second
method offers greater creative control
over individual elements. Photoshop CS4
offers more than just pixel enhancing tools
for great digital photography.
Product Photoshop CS4
Made by Adobe
Price $699, Upgrade $199
Pros Powerful tool to develop high
dynamic imagery
Cons Requires experience in
advanced photography and
Photoshop
Rating
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WORDS BY LISA P. HILL
PHOTO 1 PHOTO 2 FINAL PHOTO
