Legacy ImageMagick Discussions Archive

Is there any simple method to decrease image contrast? Option that i found for decreasing this value by convert program (+contrast) need to be passed twenty times to decrease twenty levels.Option -level works fine, but only for increasing contrast...Is any manner to decrease contrast insted of using +contrast?

I had the same problems...

-level can use negative and larger than 100% to de-contrast, but it is not very nice, or precise.

Then in IM 6.4.2 I added +level to increase contrast. Where -level maps the given values to zero/max. +level maps zero/max to the given values.

I went further to also add +/-level-colors which is the same as level but with the per-channel values being given as colors rather than numbers.

The +level-colors form thus will map a black and white image to any color gradient you specify (it does not even need to be RGB colorspace!)

All four and other related operators are detailed in IM Examples, Color Modifications, Global Color Adjustments

see my scripts, bcimage or plm, at http://www.fmwconcepts.com/imagemagick/index.html