Canon EOS Rebel T5i 18-55mm IS STM Lens Kit - Manual (Page 299)

299
3 Custom Function SettingsN
C.Fn II: Image
C.Fn-3 Highlight tone priority
0: Disable
1: Enable
Improves the highlight detail. The dynamic range is expanded from the
standard 18% gray to bright highlights. The gradation between the grays
and highlights becomes smoother.
With setting 1, the Auto Lighting Optimizer (p.125) is automatically set to
[Disable] and the setting cannot be changed.
With setting 1, noise (grainy image, banding, etc.) may become slightly
more pronounced than with setting 0.
With setting 1, the settable range will be ISO 200 - ISO 12800 (up to ISO
6400 for movies).
Also, the icon will be displayed on the LCD monitor and in the
viewfinder when highlight tone priority is enabled.
COP
Y