|
 |
 |
|
|
| |
Trade
Tricks: Understanding The Histogram
Use This Simple Tool To
Ensure The Best Exposure
By Ibarionex R. Perello
|
|
| |
The LCD screens of digital cameras
have been a boon to photographers. The immediate display of the image
is instant confirmation that we’ve successfully created the
photograph. Yet, when an accurate exposure is critical, there’s
another tool to ensure the best image possible.
Found in high-end digital compact and SLR cameras, the histogram
is a graphical representation of an image’s tonal range.
Available for display during playback, information on the highlight,
midtone and shadow content of a photograph is displayed as a graph
with a series of peaks and valleys. The mountain-like form
displays a range from the deepest shadow to the brightest white. |
|
| |
|
|
| |
 |
|
| |
|
|
| |
The goal is to have as much detail (data)
as possible for the entire tonal range. As with traditional
photography, you want to avoid over- or underexposure that results
in little to no detail. A highlight may be blown out or a shadow reveal
only a textureless black. Using the histogram is one of the
best ways to determine whether you’re risking a bad exposure.
If the image is overexposed, the histogram will not only be heavily
weighted toward the right of the graph, but data will appear to be
falling beyond the range of the graph. Called “clipping,”
data or detail is lost because it’s beyond the sensor’s
ability to capture that level of “brightness” at that
exposure. There’s no “fixing” the missing detail
in such a digital image because there’s literally no data to
adjust and control.
When the image is underexposed, the shadow area becomes a muddy gray
or a featureless black. There will be little to no detail or texture
revealed. If you attempt to fix this by lightening the image, the
result often is a shadow area filled with signal noise.
So use the histogram to confirm you have a good exposure. The images
on this page are a normal exposure and an under- and overexposed photograph
of the same scene. While the well-exposed image delivers a histogram
that reflects the quality of the exposure, the other images reveal
the loss of data due to the under- and overexposure.
You can adjust the exposure by using the camera’s exposure
compensation control or, if the camera has a manual-exposure mode,
by adjusting the shutter speed or aperture. Even an adjustment
of one ƒ-stop results in a significant change of information
captured by the camera’s CCD.
The best way to understand the histogram is to use it.
Shoot several images of a scene at different exposure levels and compare
the histograms. When displayed on your computer monitor, the photograph
will exhibit a significant difference in highlight and shadow details.
You’ll also see how much more flexibility and control is available
for editing an image when it is rich with good tonal and color information.
And you’ll discover the indispensable tool that is the histogram.
|
|
| |
|
|
|
Home | Articles
& Reviews | Current
Issue | Past Issues
Staff & Contributors | Photo
Books | HelpLine
| Glossary
Advertiser
Info | Links | Shopper
| Subscriptions | eStore
Account Inquiry | Submissions
| Contact Us | About
Us
PCPHOTO Magazine
is a publication of the Werner Publishing Corporation
12121 Wilshire Boulevard, 12th Floor, Los Angeles, CA 90025
Copyright© 2026 Werner Publishing Corp.
|
|
|