[Gimp-user] -crop formula

[Bob Meetin]

I have a batch of images all the same size, 1488x2240 pixels.  I could 
use a pointer for a formula that would crop each image to a specific 
size and keep the same proportion, roughly 2:3, or perhaps crop to a 3:4 
proportion.  For instance crop the center 744x1120 pixels (50% of height 
or width). 

I would like to be able to plug in a specific size either in % (50%, 
33%, etc) or dimensions. 

Thx, Bob