This post by Tushar (that is very great) inspired me to share how do I compare PDFs
I do not store old revisions in DFT files but I do in PDF files.
Adobe acrobat have a great tool to compare PDFs but I don't own a license to use it.
The idea is to translate a PDF into an image and then do some image overlay and compare.
While digging the net on how to covert a PDF into an image by API I found on github that someone already done it:
I just wrote a GUI in VB more user friendly than the shell usage.
Due to a bug I do also copy the selected PDFs in a local temp folder prior to use it.
It also work nice with shaded views
Hope it helps guys like me who don't store old revisions in DFTs