I am sure I am the only one in the world who uses Imagemagick's convert command, and if not, I am sure I am the only one with this problem.
But maybe there is ONE single individual who ran into the same problem and can help me.
I use convert to enhance the levels on an image. Generally to increase contrast so the picture becomes more black&white instead of gray.
When I use
convert -level 12%,78%,0.7 in.pnm out.pnm
it works fine and as expected.
However, when I do:
convert -level 30,200,0.7 in.pnm out.pnm
it yields a blank (white) image.
There should be no difference between the two parameter sets. When no percent sign is added, it uses absolute values for black_point and white_point. When a percent sign is added, it means convert uses a percentage of the full scale value.
Does anyone see what I do wrong?
Version: ImageMagick 6.0.6 11/29/04 Q16 http://www.imagemagick.org