Paperless office; document/image processing
- How to obtain the density (DPI / PPI) of a PGM file -- anyone know? ImageMagick does not cut it.
Running this gives the geometry but not the density:
$ identify -verbose myfile.pgm | grep -iE 'geometry|pixel|dens|size|dimen|inch|unit'
There is also a “Pixels per second” attribute which means nothing to me. No density and not even a canvas/page dimension (which would make it possible to compute the density). The “Units” attribute on my source images are “undefined”.Suggestions?
- Safe enough for public webserver?
I just discovered this software and like it very much.
Would you consider it safe enough to use it with my personal documents on a public webserver?
- PDF renders radically different between Adobe Acrobat® vs. evince & okular (GhostScript-based)
The linked doc is a PDF which looks very different in Adobe Acrobat than it does in evince and okular, which I believe are both based on the same GhostScript library.
So the question is, is there an alternative free PDF viewer that does not rely on the GhostScript library for rendering?
#AskFedi
- [solved] TIFF → DjVu conversion produces bigger file from bilevel doc than color
I would like to get to the bottom of what I am doing wrong that leads to black and white documents having a bigger filesize than color.
My process for a color TIFF is like this:
①
tiff2pdf
②ocrmypdf
③pdf2djvu
Resulting color DjVu file is ~56k. When
pdfimages -all
runs on the intermediate PDF file, it shows CCITT (fax) is inside.My process for a black and white TIFF is the same:
①
tiff2pdf
②ocrmypdf
③pdf2djvu
Resulting black and white DjVu file is ~145k (almost 3× the color size). When
pdfimages -all
runs on the intermediate PDF file, it shows a PNG file is inside. If I replace step ① with ImageMagick’sconvert
, the first PDF is 10mb, but in the end the resultingdjvu
file is still ~145k. And PNG is still inside the intermediate PDF.I can get the bitonal (bilevel) image smaller by using
cjb2 -clean
, which goes straight from TIFF to DjVu, but then I can’t OCR it due to the lack of PDF intermediate version. And the size is still bigger than the color doc (~68k).update ---
I think I found the problem, which would not be evident from what I posted. I was passing the
--force-ocr
option toocrmypdf
. I did that just to push through errors like “this doc is already OCRd”. But that option does much more than you would expect: it transcodes the doc. Looks like my fix is to pass--redo-ocr
instead. It’s not yet obvious to me why--force-ocr
impacted bilevel images more.#askFedi