Apple Shake 4 - Manual (Page 446)

446 Chapter 15 Image Processing Basics
If you look back at the original log-to-lin conversion graph, the curve suggests that it
should continue past 1, but so far, the curve has been clipped at 1. In the following
illustration, the red line represents the potential information derived from the color
conversion. The curve is clipped at 1 because values can only be stored from 0 to 1 in 8
or 16 bits.
As the illustration suggests, if data could be preserved above 1, you could always
access the data, and life would be happy. Fortunately (by design), you can convert your
images to a higher bit depth called “float.” Whereas 8 and 16 bits are always in a 0 to 1
range, float can describe any number and is ideal for working with logarithmic images
when converting to linear representation and back to log representation. If you keep
your images in linear color because you are reading out to a linear format, float is not
necessary.