I've been scanning documents for ages, but more recently than before. Especially in large numbers.
So I use the ADF (Automatic Document Feeder) on my HP-6400 scanner with XSane to direct the images to a Download directory.
But inevitably they are off by a fraction, no more than a fraction, like 0.5°, but my eye still catches it. And deems it unprofessional.
But if you have fifteen pages, opening each one to correct them is a royal PITA. And time consuming to boot.
So I cast about for ways to fix it:
- Looked for GIMP plugins. There was one once upon a time called Deskew but it seems to have evanesced.
- Looked for options under Imagick. Its convert and mogrify scripts are very capable. There is a deskew option, but I did not find any simple description of how to use it.
- Looked for other options...
And it is a positive dream to use. Most of the parameters are precompiled with defaults. I changed the binary RRGGBB background (-b) parameter to white (fffff) from its default black (000000), but frankly haven't had the time to examine whether that was really necessary.
So the command at its simplest for me was
deskew -o output.jpg -b ffffff input.jpg
Yes, you have to know what you're doing: unzip the download, move the entire resulting Deskew directory to somewhere useful, e.g., /data/graphics You also need to
chmod +x deskew
to make it executable and adjust your .bashrc to include that path, or simply prepend it to the deskew command:
So, generally, a breeze.
A very elegant piece of work.