python-pillow/Pillow — pull request #745 by gcq (2014-06-28 21:38:25+00:00)
Title: Better BMP default DPI

Pixels are squares, and vertical and horizontal DPI should be the same most of the time, but the JPEG plugin uses two values, so i use two too.

The chosen default (96) is the default DPI in WIndows. Let me know if you are ok with it.