If you don't want to do any programming, your best bet might be the versatile wand:
http://imagejdocu.tudor.lu/doku.php?id=plugin:segmentation:versatile_wand:startHere is a list of imageJ plugins:
http://rsbweb.nih.gov/ij/plugins/index.htmlHere is a list of Fiji plugins:
http://pacific.mpi-cbg.de/wiki/index.php/Category:PluginsIf you can't find anything in either of those 2 lists, the plugin you are looking for probably doesn't exist.
Kurt_P wrote
Is there some plugin that allows for a two band or band-stop threshold adjustment? I black and white pictures and I want to have two ends of the spectrum (let's say 0 to 36 and 220 to 255 just as an example) instead of just one.
Thanks ahead of time