White-out center margin of a scan (the crease) on successive pages?

Is there a way to White-out center margin of a scan (the crease) on successive pages? A white text box would work. But how can this be applied over several pages? (Ideally, an even-odd range in cases of a crease or line [appears darker] on the side of a document, alternating pages.

I thought of a white blank watermark, but the crease runs vertically and I don't know that this will work.

Any other options? 

Tx