Canon EOS-1DX Instruction Manual page 265

To rotate an image, set [51: Auto rotate] to [OnzD]. If [51: Auto rotate]
is set to [OnD] or [Off], the [b Rotate image] setting will be recorded to
the image, but the camera will not rotate the image for display.
Press the <Q> button during index display to switch to the single-image
display and the Quick Control screen will appear. Pressing the <Q>
button again will return to the index display.
For images taken with another camera, the functions you can select may
be limited.
Q Quick Control During Playback
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