How to fix my PDFs ?

August 8, 2009 7:01 PM

How to adjust brightness/contrast in PDF files?

I have several PDF files which were created by scanning some material containing text, but some of them came up with unnecessarily dark backgrounds, that is, with borked contrast. If I print them, they will waste too much ink, and the printouts will be harder to read. I know that there's a program that allows the brightness/contrast to be adjusted, but I have forgotten its name, though I spent 3 hours downloading various programs with no luck. :(
So what I want to do ideally is to simply select the page numbers (that are over 100 pages, by the way) and do a batch adjustment of whatever is needed.

Do you know a program that could help?

posted by GrooveStix to computers & internet (6 comments total)

Previously.
posted by scalefree at 7:49 PM on August 8

Yes, except that I am using Windows XP. :(
posted by GrooveStix at 7:56 PM on August 8

Have you tried to the demo of Acrobat (not reader?) They have a 30 day trial.
posted by bigmusic at 5:09 AM on August 9

Yes I have, and unfortunately there's nothing that allows me to change the brightness/contrast. I just realized that I have Macs at work, so if anyone knows a solution that involves Macs go ahead and say it. I'll try the one that scalefree suggested, even though it is very vague.
posted by GrooveStix at 10:07 AM on August 9

If you're running OSX, you can probably get ImageMagick, which is one of the canonical ways to manipulate images on *nix. Together with Ghostscript, you can manipulate PDFs with the command line convert tool.

Finally, I found this which tells you (in theory) how to manipulate brightness and contrast (using convert). Just substitute the .png used in the instructions with your .pdf.
posted by stufflebean at 10:40 AM on August 9

Sorry, I missed that your native platform is Windows XP. That being said, I know you can get distributions of ImageMagick and Ghostscript for Windows, so perhaps the same approach is valid.
posted by stufflebean at 10:42 AM on August 9