Canon EOS REBEL T6i Instruction Manual page 334

p Specifying Images for a Photobook
Specifying All Images in a Folder or on a Card
You can specify all the images in a folder or on a card at once.
RAW images and movies cannot be specified.

Do not specify images already specified for a photobook in another

camera for another photobook with this camera. The photobook settings
may be overwritten.
334
When [x1: Photobook Set-up] is set
to [All images in folder] or [All images
on card], all the images in the folder or
on the card will be specified.
To cancel the image specification, select
[Clear all in folder] or [Clear all on
card].