Canon Camera, Hackers Manual

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C H A P T E R 4 Teach Your Camera New Tricks
Custom curves are, of course, not restricted to compression of the dy-
namic range. They can also be used for creative purposes. When you assign
different-shaped curves to different color channels, you may get interesting
color shifts. Curves with hills and valleys result in an effect known as the
Sabbatier effect.
When doing such work, you should shoot RAW in any case. The curves are
only applied to the JPEG output
5
. If you are not happy with the outcome,
you still have the original and unmodified image in the RAW file. And by
redeveloping the RAW file (section 4.5.5), you can try out another curve.
As a matter of fact, all of these modifications using curves would also
be possible in a post-processing stage—at least when you opt to shoot
RAW. Image editing programs such as
Photoshop or Paintshop Pro allow for
such modifications of the tonal range. However, using curves in the camera
may help you to realize your visualization of the scene earlier and to redo a
shot when the outcome does not match your expectations.
5 They also affect the preview images embedded into DNG files because the
previews are derived from the JPEG image.
Figure 4-30
Typical curve for achieving a Sabbattier
effect. The different curves for the
single color channels will cause color
shifts in midtones and highlights.