Remove white border (batch) OS X

[etherspin]

Hi ! I have a bundle of files I have been able to convert into directories of images , some of them graphic novels, old manga etc and I've found that they do become feasible on the cybook when i take the folder of images and use calibre to convert to .mobi ...
ALMOST feasible, its just the centimeter and a half of white space around most images, the margin of the original book/manga .
some of the pages in the directory are landscape (usually like 10 pages out of about 400 ) so i cant simply apply a straight, indiscriminate crop on all images, Im looking for something in OS X that will do a white space crop for the directory, Calibre has the option but it doesnt seem brutal enough, either that or the fact that it outputs mobi pocket, not pdf means the images no longer fill the page..
I'm so close guys.. i just read my copy of tezukas "Buddha, volume 1" it was superb but that border going away would make it easy on the eye!