Legacy ImageMagick Discussions Archive

The "Levels" command is well known to Photoshop or GIMP users, and quite useful.
ImageMagick supports the same function using the -level command line option (not discussing APIs) . This is documented here

According to the docs, one can specify -level black_point,white_point (not interested in ...

convert -version
Version: ImageMagick 6.8.6-10 2016-05-30 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2013 ImageMagick Studio LLC
Features: DPC
Delegates: bzlib cairo djvu fftw fontconfig freetype jng jp2 jpeg lcms lzma openexr pango pangocairo png png rsvg tiff x xml zlib ...

Using version 7.0.3:
magicj img_0369.jpg img_0369.bmp results in a 5625k file (I'll use this as a reference)

magick img_0369.jpg -format jp2 -define jp2:rate=16 img_0369_16.jp2 results in a 351k file which is exactly 16:1 compression rate.

magick img_0369.jpg -format jp2 -quality 75 img_0369 ...

I've been using ImageMagick version 6.8.6-10 (linux) for a while, converting images for a project from JPEG to JP2
convert INPUT -format jp2 -quality 50 OUTPUT
Experimentation showed that this quality level yielded a good visual quality (very little distortion visible to the eye) while also ...