Canon PIXMA MG4200 Series On-Screen Manual page 757

Note
On the Advanced Mode tab, you can specify the cropping frame size by entering the values into
(Width) and (Height) in Input Settings.
Input Settings
You can rotate a cropping frame 90 degrees by clicking
(Switch Aspect Ratio) is not available when Output Size is Flexible.
Creating Multiple Cropping Frames
In thumbnail view
You can only create one cropping frame per image.
In whole image view
Click and drag the mouse in a space outside the existing cropping frame to create a new cropping
frame in the Preview area. The new cropping frame will be the active cropping frame, and the old
cropping frame will be the unselected cropping frame.
You can create multiple cropping frames and apply different scan settings to each cropping frame.
You can also select multiple cropping frames by clicking them while pressing the command key.
If you select multiple cropping frames and change the settings on a tab at the right of ScanGear, the
(Switch Aspect Ratio). However,