Canon EOS 100D Instruction Manual page 251

Q Quick Control for Playback
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.
For images taken with another camera, the options you can select may be
limited.
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