Image Processing Reference
In-Depth Information
Using the Exposure Control
The Exposure slider works like the exposure compensation setting on your camera. The
numbers shown are equivalent to f-stops, with higher numbers adding more light to the
scene and negative numbers subtracting light. The slider has a range of four stops in
either direction, which gives you a great deal of control over the image after the capture.
Large changes (over one full stop of additional exposure) are likely to introduce noise
into the image that will need to be dealt with, so don't depend on Camera Raw to rescue
every poorly exposed image you throw at it. If you've used the Levels command in Photo-
shop Elements or Photoshop, the Exposure control is similar in function to the far right,
or white point, slider. The Exposure control in Camera Raw is much more powerful than
a simple white point adjustment in the Levels command though, as you'll see here.
Note: It's very seldom that you will make only a single adjustment in Camera Raw. Adjustments to
exposure typically lead to adjustments in the other controls as well. The following examples are typical of
the steps involved in correcting exposure.
I spend more time explaining exposure than any of the other topics in this chap-
ter because exposure is critical to the quality of your converted image and it is the most
powerful control in Adobe Camera Raw, allowing you to perform miracles or digital
murder on your images.
Correcting Underexposure
In the typical image, you'll be adjusting the exposure to bring the white point of the
image to the far right of the histogram. Underexposed images, such as the one in Fig-
ure 3.5, will need to have exposure added by moving the slider to the right. Although
this particular image is an extreme example of underexposure, it does demonstrate
what can be done by using RAW.
Figure 3.5 The original RAW
image is severely underex-
posed. Had this been a JPEG
file, the amount of detail recov-
erable would have made this
image unusable. (Image cour-
tesy of Art Morris, www )
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