The ability to quickly make adjustments for any type image is great! If you are looking at something that needs more than one adjustment it can be difficult but not impossible if there's enough knowledge about how imagemagick works behind-the scenes (which I do have). For example - my client was trying out different colors when we noticed some areas were too dark or light so she asked me what settings would help her achieve this look/looks better without knowing anything specific like "I want these two pixels here changed from red->blue" etc.. It took us quite awhile before figuring things out together because sometimes just changing an option will change everything else around which makes finding exactly where your issue lies very hard unless its already known by someone who knows their stuff inside & outside :).