PDFs Are Weird

[drcpunk]

Tonight, I was going through the files from last month that need filing and came on two pdfs of a larp that a bunch of folks wrote a few years ago.

One of the authors sent out the first file. Another asked for a correction.

The first author made the correction and sent the second file. The whole thing, from sending out file #1 to sending out file #2 took maybe 2 minutes. It's not like the first author did anything fancy -- one word was changed.

I opened both files briefly to make sure I was deleting the correct one, and saw that one file was 157 kb and one was 281 kb.

One single word was changed. I do not understand how pdfs decide how big they are going to be.

Comments

[madfilkentist]

Was the correction made to the PDF directly, rather than by re-generating it from a source file? PDFs aren't designed to be changed easily, and a change often consists of appending a new piece to the file.

[drcpunk]

An excellent question. I'd have done it in the non-PDF source document, but I don't actually know how the author did it.

[gorgeousgary]

Well, you learn something new every day...

I've had similar experiences with certain PDF's I create for work meetings. Sometimes, I take a bunch of files, make PDF's, then add a big bold number in the upper right corner keyed to the meeting agenda. This often causes 80 or 90 kb files to become 200 or 300 kb files. I save them again as Reduced Size PDF's and they're back down close to their original size.

[avram]

It's possible they used different settings when saving the new file.

Just checking the PDFs we have on file for NYRSF #340, I see the file we generate for Lulu is 4.9 MB, while the one for Weightless is 7.8 MB. Same issue. The Lulu version is black and white, while the Weightless version has color images, and includes a working table of contents and hyperlinks.