help with converting pbm to png (Terry Todd)

Discussion:

geo cherchetout

2010-10-27 20:08:38 UTC

I have a .pbm file that was extracted from a .pdf file from a
microfilm reader / scanner. When I run "convert file.pbm file.jpg"
it works fine. I get back a good image that looks just like it
does in the .pdf file. However when I run "convert file.pbm
file.png" it is all grainy and almost impossible to read. I have
tried all kinds of density and other options to no avail. Any
suggestions on how to get a quality png image would be appreciated.

A very good solution I use often : optipng payroll*pbm

Terry Todd

2010-10-28 15:54:27 UTC

Permalink

I tried optipng and got the same results.

Post by geo cherchetout

A very good solution I use often : optipng payroll*pbm
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Wolfgang Hugemann

2010-10-29 05:04:20 UTC

Permalink

Terry,

I regularly use pdfimages to losslessly extract images from PDF files
and and the convert these PBMs to TIFFs or GIFs with ImageMagick.
Although using various versions of IM, I have never encountered any
problems with that. I have just tried to use PNG instead of GIF and have
met no problems with doing so.

Considering your PDF: Extracting the images with pdfimages, I get the
same results as you. But I meet no problems when converting them to
PNGs; they look just the same as the originals.

BTW: PNG does a much better job on compression than TIFF (and even GIF),
so perhaps I should switch to PNG in the future...

At the moment I'm using ImageMagick 6.6.3-0 2010-07-01 Q16 on Windows XP
and Windows 7, 32 bit.

Perhaps this is a problem with the very IM version you use, check with
http://www.imagemagick.org/script/changelog.php.

Greetings from Germany
Wolfgang Hugemann