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CHAPTER 2: PHOTO EDITING 91
High Dynamic Range
Dynamic range is the range of light that can be captured in a photo, from the
darkest shadows to the brightest highlight. Digital camera sensors (or film in
traditional cameras), unlike the human eye, can only capture a limited dynamic
range when photographing in extreme light conditions or dark environments. For
instance, a landscape will have a vast dynamic range of light that cameras are not
able to completely capture, and photos either have enough exposure of shaded
areas (like the mountain) but with blown highlights in the sky, or have clear blue
sky but with dark shades. A bright outdoor or dark indoor scene most often also
have exposure problems, resulting in darkly lit subjects or washed out highlights.
PhotoImpact's High Dynamic Range (HDR) compensates for a digital camera's
limitations, and tries to resolve exposure problems that photographers frequently
encounter when shooting photos that contain dramatic differences between light
and shades. It produces an optimized image by combining different copies of the
same scene and uses different exposure levels to extend its perceivable tonal
range. To produce such an image, multiple shots with different exposures are first
combined into a High Dynamic Range (HDR) image which will record the complete
tonal information combined from all the shots. This information is then used to
produce a final optimized image.
High Dynamic Range also has tools that let you fix areas in your photos that are
different or retain areas that you don't want to be adjusted before you combine
them to produce the HDR image. This eliminates the blurred areas in the HDR
image due to the differences between photos.
The three photos on the left were taken with different exposure levels then combined into a
single image to create the properly exposed image.
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