Canon MARK IV User Manual (en)

Normally, the Self Cleaning Sensor Unit will eliminate most of the dust 
that might be visible on captured images. However, in case visible dust 
still remains, you can append the Dust Delete Data to the image to later 
erase the dust spots. The Dust Delete Data is used by Digital Photo 
Professional (provided software) to erase the dust spots automatically.
Get a solid-white object (paper, etc.).
Set the lens focal length to 50mm or longer.
Set the lens focus mode switch to <g> and set the focus to infinity 
∞). If the lens has no distance scale, look at the front of the lens and 
turn the focusing ring clockwise all the way.
Select [Dust Delete Data].
Under the [2] tab, select [Dust 
Delete Data
], then press <0>.
Select [OK].
Turn the <5> dial to select [OK], 
then press <0>. After the automatic 
sensor cleaning ends, a message will 
appear. Although there will be a 
shutter sound, a picture is not taken.
 Appending Dust Delete Data
Obtain the Dust Delete Data