Converting a PDF to PNG

Question

I m trying to convert a PDF to a PNG image  at least the cover of one   I m successfully extracting the first page of the PDF with pdftk  I m using imagemagick to do the conversion   convert cover pdf cover png   This works  but unfortunately the cover png comes through incorrectly rendered  some of the alpha object in the PDF aren t rendered properly   I know ImageMagick uses GhostScript to do the conversion and if I do it directly with gs I can get the desired results  but I d rather use the convert library as it has other tools I d like to leverage   This command in GhostScript accomplishes the desired image   gs -sDEVICE pngalpha -sOutputFile cover png -r144 cover pdf   I m wondering is there any way to pass arguments through convert to GhostScript or am I stuck with calling GhostScript directly

User · Answer

You can use ImageMagick without separating the first page of the PDF with other tools. Just do

convert -density 288 cover.pdf[0] -resize 25% cover.png

Here I increase the nominal density by 400% (72*4=288) and then resize by 1/4 (25%). This gives a much better quality for the resulting png.

However, if the PDF is CMYK, PNG does not support that. It would need to be converted to sRGB, especially if it has transparency, since Ghostscript cannot handle CMYK with alpha.

convert -density 288 -colorspace sRGB -resize 25% cover.pdf[0] cover.png

User · Answer

As this page also lists alternative tools I ll mention xpdf which has command line tools ready compiled for Linux Windows Mac  Supports transparency  Is free for commercial use - opposed to Ghostscript which has truly outrageous pricing   In a test on a huge PDF file it was 7 5  faster than Ghostscript    It also has PDF to text and HTML converters

User · Answer

Try to extract a single page     page   4  gs -sDEVICE pngalpha -dFirstPage   page  -dLastPage   page  -o thumb png -r144 input pdf

User · Answer

To convert pdf to image files use following commands   For PNG gs -sDEVICE png16m -dTextAlphaBits 4 -r300 -o a png a pdf  For JPG gs -sDEVICE jpeg -dTextAlphaBits 4 -r300 -o a jpg a pdf  If you have multiple pages add to name  03d gs -o a 03d jpg a pdf  What each option means    sDEVICE  jpeg pngalpha png16m     - filetype -o - output file   stdout to stdout  -dTextAlphaBits 4 - font antialiasing  -r300 - 300 dpi

User · Answer

Couldn t get the accepted answer to work  Then found out that actually the solution is much simpler anyway as Ghostscript not just natively supports PNG but even multiple different  encodings     png256 png16 pnggray pngmono       The shell command that works for me is   gs -dNOPAUSE -q -sDEVICE pnggray -r500 -dBATCH -dFirstPage 2 -dLastPage 2 -sOutputFile test png test pdf   It will save page 2 of test pdf to test png using the pnggray encoding and 500 DPI

User · Answer

Out of all the available alternatives I found Inkscape to produce the most accurate results when converting PDFs to PNG  Especially when the source file had transparent layers  Inkscape succeeded where Imagemagick and other tools failed    This is the command I use   inkscape   pdf  -z --export-dpi 600 --export-area-drawing --export-png   pngfile    And here it is implemented in a script      bin bash  while      -gt 0    do  pdf  1 echo  Converting   pdf       pngfile  echo   pdf    sed  s    w    png    inkscape   pdf  -z --export-dpi 600 --export-area-drawing --export-png   pngfile  echo  Converted to   pngfile   shift  done  echo  All jobs done  Exiting

User · Answer

My solution is much simpler and more direct  At least it works that way on my PC  with the following specs     me home  my folder  uname -a Linux home 3 2 0-54-generic-pae  82-Ubuntu SMP Tue Sep 10 20 29 22 UTC 2013 i686 i686 i386 GNU Linux   with  me home  my folder  convert --version Version  ImageMagick 6 6 9-7 2012-08-17 Q16 http   www imagemagick org Copyright  Copyright  C  1999-2011 ImageMagick Studio LLC Features  OpenMP   So  here s what I run on my file pdf   me home  my folder  convert -density 300 -quality 100 file pdf file png

User · Answer

I ll add my solution  even thought his thread is old  Maybe this will help someone anyway   First  I need to generate the PDF  I use XeLaTeX for that   xelatex test tex   Now  ImageMagick and GraphicMagic both parse parameters from left to right  so the leftmost parameter  will be executed first  I ended up using this sequence for optimal processing   gm convert -trim -transparent white -background transparent -density 1200x1200 -resize 25  test pdf test png   It gives nice graphics on transparent background  trimmed to what is actually on the page  The -density and -resize parameters  give a better granularity  and increase overall resolution   I suggest checking if the density can be decreased for you  It ll cut down converting time

User · Answer

You can use one commandline with two commands  gs  convert  connected through a pipe  if the first command can write its output to stdout  and if the second one can read its input from stdin    Luckily  gs can write to stdout      -o  stdout        Luckily  convert can read from stdin  convert -background transparent - output png     Problem solved     GS used for alpha channel handling a special image   convert used for creating transparent background  pipe used to avoid writing out a temp file on disk    Complete solution       gs -sDEVICE pngalpha            -o  stdout                   -r144 cover pdf                                        convert                         -background transparent      -                             cover png     Update  If you want to have a separate PNG per PDF page  you can use the  d syntax   gs -sDEVICE pngalpha -o file- 03d png -r144 cover pdf   This will create PNG files named page-000 png  page-001 png       Note that the  d-counting is zero-based -- file-000 png corresponds to page 1 of the PDF  001 to page 2     Or  if you want to keep your transparent background  for a 100-page PDF  do  for i in  1  100   do                                           gs -sDEVICE pngalpha              -dFirstPage    i               -dLastPage    i                -o  stdout                     -r144 input pdf                                            convert                           -background transparent        -                               page-  i  png                                           done

User · Answer

For a PDF that ImageMagick was giving inaccurate colors I found that GraphicsMagick did a better job     gm convert -quality 100 -thumbnail x300 -flatten journal pdf  0   cover jpg

User · Answer

One can also use the command line utilities included in poppler-utils package   sudo apt-get install poppler-utils pdftoppm --help pdftocairo --help   Example   pdftocairo -png mypage pdf mypage png

[image] Converting a PDF to PNG

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