Adding new image to wallpaper folder in BitPim: LG PM-325

As part of my experiment to test uploading new wallpaper to the PM-325 I
had to add an image to the Wallpaper folder in BitPim.  The image I want
to use is already formatted for the PM-325 (128x160 JPEG).  If I open
the Wallpaper folder and activate the Add Wallpaper button then choose
the source .jpeg file,  the Image Preview window opens and makes me crop
the image.  The new cropped image is converted to .bmp.
 
I assume the cropping and image type are force by some setting in BitPim
for native image size and image type which is not set correctly for the
PM-325.  Where is that information stored? I've glanced through the
files com_lgpm325.py and p_lgpm325.p but did not see any code which
obviously controlled the native image settings.
 
-phil