Adobe Photoshop CS6 User Manual page 255

High dynamic range images
About high dynamic range images
Take photos for HDR images
Features that support 32-bpc HDR images
Merge images to HDR
Adjust displayed dynamic range for 32-bit HDR images
About the HDR Color Picker
Paint on HDR images
About high dynamic range images
The dynamic range (ratio between dark and bright regions) in the visible world far exceeds the range of human vision and of images that are
displayed on a monitor or printed. But whereas human eyes can adapt to very different brightness levels, most cameras and computer monitors
can reproduce only a fixed dynamic range. Photographers, motion picture artists, and others working with digital images must be selective about
what's important in a scene because they are working with a limited dynamic range.
High dynamic range (HDR) images open up a world of possibilities because they can represent the entire dynamic range of the visible world.
Because all the luminance values in a real-world scene are represented proportionately and stored in an HDR image, adjusting the exposure of an
HDR image is like adjusting the exposure when photographing a scene in the real world.
Merging images of different exposures to create an HDR image
A. Image with shadow detail but highlights clipped B. Image with highlight detail but shadows clipped C. HDR image containing the dynamic
range of the scene
In Photoshop, the luminance values of an HDR image are stored using a floating-point numeric representation that's 32 bits long (32-bits-per-
channel). The luminance values in an HDR image are directly related to the amount of light in a scene. By contrast, non-floating point 16- and
8-bpc image files store luminance values only from black to paper white, reflecting an extremely small segment of dynamic range in the real world.
In Photoshop, the Merge To HDR Pro command lets you create HDR images by combining multiple photographs captured at different exposures.
Because an HDR image contains brightness levels that far exceed the display capabilities of a standard 24-bit monitor, Photoshop lets you adjust
the HDR preview. If you need to print or use tools and filters that don't work with HDR images, you can convert them to 16- or 8-bpc images.
Take photos for HDR images
Keep the following tips in mind when you take photos to be combined with the Merge To HDR Pro command:
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