ImageMagick memo

density return is different from version

■version 6.9.1-0
$ identify -version
Version: ImageMagick 6.9.1-0 Q16 x86_64 2015-04-14 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: DPC Modules
Delegates (built-in): bzlib fontconfig freetype jng jpeg ltdl lzma png x zlib

$ identify -format "%x" 1.jpg
72    ←density

$ identify -format "%[resolution.x]" 1.jpg
72    ←density

■version 6.5.4-7
# identify -version
Version: ImageMagick 6.5.4-7 2014-02-10 Q16 OpenMP http://www.imagemagick.org
Copyright: Copyright (C) 1999-2009 ImageMagick Studio LLC

# identify -format "%x" 1.jpg
72 PixelsPerInch        ←added unit

# identify -format "%[resolution.x]" 1.jpg
    ←nothing return