Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 405)

Setting MF peaking (outline emphasis)
In Live View shooting, edges of subjects in focus can be displayed in color to make focusing
easier. You can set the outline color and adjust the sensitivity (level) of edge detection.
1.
Select [ : MF peaking settings].
2.
Select [Peaking].
Select [ On ].
3.
Set the level and color.
Set it as necessary.
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