Canon PIXMA MG4200 Series On-Screen Manual page 646

Note
To enlarge/reduce the scanned image, enter values into
Output Settings or specify a value (by 1%) for %. Although the maximum value available for
% depends on the Output Resolution, it can be specified for up to 19200 dpi (the maximum
available output resolution).
Paper Size (L, A4, etc.) & Monitor Size (1024 x 768 pixels, etc.)
(Width), (Height) and scale cannot be specified. The preview image will be cropped
according to the selected output size and resolution. The portion within the cropping frame will be
scanned at the size of the selected paper/monitor size. You can drag the cropping frame to enlarge,
reduce, or move it while maintaining the aspect ratio.
Add/Delete...
Opens the Add/Delete the Output Size dialog, in which you can specify custom output sizes.
In the Add/Delete the Output Size dialog, you can specify multiple output sizes and save them at
one time. Saved items will be registered to the Output Size list and can be selected, along with the
predefined items.
Add
To add a size, select Print or Image display for Destination, then enter Output Size Name, Width,
and Height then click Add. For Unit, you can select inches or mm when Destination is Print but
you can only select pixels when Destination is Image display. The name of the added size
appears in Output Size List.
Click Save to save the items listed in Output Size List.
Delete
To delete an item, select it in Output Size List and click Delete. Click Save to save the items listed
in Output Size List.
Important
You cannot delete predefined output sizes such as A4 and 1024 x 768 pixels.
Note
Save up to 10 items for each destination.
An error message appears when you enter a value outside the setting range. Enter a value
within the range displayed in the message.
Note
See "Adjusting Cropping Frames" for details on cropping frames.
For details on whether or how the cropping frame is initially displayed on a preview image, see
Cropping Frame on Previewed Images in
(Switch Aspect Ratio)
(Width) and
"Preview Tab" (Preferences dialog).
(Height) in