How can I crop uneven-colored margins on scanned pdf documents?

Question

Hello,

I have a bunch of scanned pdf documents and I would like to crop the margins on each page. I would like to do this in an automated way, as the number of pages to process is in the hundreds.

Unfortunately, the color of the margins is not even, because the scanner was larger than the paper documents and the lid did not cover them evenly. As a result, the color of the margins on a single page can vary across the whole grayscale between full white and full black. So far, I have tried ImageConverter, which picks out page margins by color filtering, but it has been quite ineffective because the color varies so much.

Off the top of my head, the solution for my problem would be a tool that picked out the text areas and cropped the page accordingly, but I couldn't google up anything like that. It would be a big plus if it were free, but I guess I can live with paying up to the 150-200$ price range, provided the software maker looked legit, the software were really worth it, and a demo version were available.

Thank you in advance for your help

Answer 1

There IS a crop tool in Adobe.  I believe even reader has the crop tool.  From your Tools dropdown menu, choose "Advanced Editing", and then the "Crop Tool".  If ALL your pages would be cropped exactly the same you can drag to select how you want it cropped.  When you're sure you've selected exactly how you want it cropped, double click in that area.  You can either click "OK" to crop just that page, or if all will be cropped the exact same way, you can choose all, or you can choose a block of pages at a time.  Once you complete the task, do NOTHING more while you look over your document to make sure you didn't crop anything you didn't want to crop.  If you find there's anything missing because you cropped too much, you can undo.

Answer 2

Well, Photoshop will do exactly that. It can load a PDF page, detect the content area and automatically crop out the margins. It will only process 1 page of a PDF at a time, but you can create an Action and run it as a batch command. The bad thing about this is when you go to save the modified PDF, it saves it in Photoshop's PDF format, which I've found to not fully compatible. Strange, since it's from the same company.

For multi-page PDFs, Acrobat (not the Acrobat Reader) has a crop tool where you have to manually draw the region to crop, but you can do that just once and apply the crop to all the pages. But you would have to be sure that all the pages have the same margin widths.