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I made a PDF diff tool for myself for one of my internships >10 years ago. One of my responsibilities was to get sign-off on any changes engineers made to sche
by rcfox 4y ago
I made a PDF diff tool for myself for one of my internships >10 years ago.
One of my responsibilities was to get sign-off on any changes engineers made to schematics. (It was a really bad internship! I ended up automating a bunch of stuff for them because my actual job was mind-numbingly boring.)
After the first few times comparing PDFs of schematics by eye, I said screw it and wrote a tool to export to PNGs and then compare them pixel-by-pixel. It saved me a ton of time and my sanity.
- crecker 4y ago> After the first few times comparing PDFs of schematics by eye, I said screw it and wrote a tool to export to PNGs and then compare them pixel-by-pixel. It saved me a ton of time and my sanity. It saved mine! I usually work with books and sometimes it's really difficult to tell 10 people to check every single page if something has been different to a previous pdf I sent. They will never be able to find all the differences because we're humans, not bot. We make mistakes.
- bob1029 4y agoRasterization prior to comparison is a really clever idea. Doing this with PDF spec code would be an absolute nightmare. Checking 2 bitmaps for equality is just a few lines of code. Many times, you aren't really concerned with the specific differences being described natively. You just want to know if a human would perceive differences between 2 copies of the "same" form.
- markrages 4y agoI wrote a tool to do this for circuit board artwork changes. It used gerbv to rasterize the vector (gerber) files, then used XOR on the pixels to make unchanged areas disappear. For such a simple tool it is quite useful.