Canon EOS-1D Mark II Instruction Manual page 50

Specifying the Preferences
Allows you to specify the grid spacing in a range of 8 to 256 pixels used when the grid is displayed
on the edit window or the edit image window.
Removing the check mark hides the [Click] button and the [Brightness adjust] button from
the main window.
If you select this checkbox, the image that has been displayed on the edit window is selected
on the main window when you close the edit window.
Select the display mode for displaying the edited and original images for comparison on the edit
or edit image window (3-6).
[Show same position in each window]
2-36
[Split single image and show]