====== farbiges PDF in schwarz/weiß wandeln ======

===== nützliches Befehle =====

  * ''pdftoppm -r 600 foo.pdf'' -> ''convert -threshold 75%''
  * ''pdf2djvu''
  * ''pdftocairo'' (nach jpg, png, tif etc.)


===== siehe auch =====

  * [[https://www.bitsgalore.org/2021/09/06/pdf-processing-and-analysis-with-open-source-tools|PDF processing and analysis with open-source tools]]