Inkscape

Inkscape is a Free and open source vector graphics editor for GNU/Linux, Windows and MacOS X.

https://inkscape.org/
https://en.wikibooks.org/wiki/Inkscape/Other_Tools
https://en.wikibooks.org/wiki/Inkscape

Generate png from svg

   1 inkscape processing.svg --export-png=processing_xhdpi.png

Resize png image by percentage value

   1 sudo apt install imagemagick
   2 convert processing_xhdpi -resize 75% processing_hdpi.png

Script genimages.py

   1 import os
   2 import sys
   3 
   4 files = os.listdir('.')
   5 
   6 for file in files:
   7     if "_xhdpi" in file:
   8         print("convert %s -resize 75%% %s "%(file, file.replace("_xhdpi","_hdpi")))
   9         print("convert %s -resize 50%% %s "%(file, file.replace("_xhdpi","_mdpi")))
  10         print("convert %s -resize 25%% %s "%(file, file.replace("_xhdpi","_ldpi")))