Canon EOS-1D X Mark III Advanced User's Manual page 612

Transferring Multiple Images at Once
Selecting images to transfer
Selecting multiple images
Transferring RAW+JPEG or RAW+HEIF images
After shooting, you can select multiple images and transfer them all at once, or you can
transfer unsent images or images that could not be sent previously.
You can continue shooting still photos as usual during transfer.
Caution
Image transfer in progress is paused while the Live View shooting/movie shooting
switch is set to <
Selecting images to transfer
1.
Select [
2.
Select [Image sel./transfer].
>. To resume image transfer, set it to <
: Image transfer].
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