http://cypherpunk-handbook.i2p/contribute.html
For most file types,
including SVG and PDF , mat2 (Metadata Anonymisation Toolkit 2) is the preferred
tool. Video and audio files can be cleaned with ffmpeg . mat2 removes metadata from images, documents, audio,
and video files. By default, it creates a new file with
metadata removed: mat2 filename.pdf
mat2 filename.png
mat2 filename.jpg exiftool can also be used but is not recommended
for PDFs : exiftool -all= filename.jpg ffmpeg...