Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
I've been trying to use Imagemagick's modulate to replicate Photoshop's Hue/Saturation layer. While just changing the hue seems to match almost perfectly (using e.g. +90 Hue in Photoshop as 100,100,150 for modulate), changing e.g the saturation on modulate to 100,150,150 does not produce the same result as +90 Hue, +50 Saturation in Photoshop. And Lightness doesn't seem to correspond either...
How would I go about finding the correct values that correspond to Photoshop's? I've been up all night trying to figure this one out, so many thanks to anyone who can shed any light
More than likely the -modulate is broken. I have not in the course of creating IM examples handled modulate formally, so have not bug fixed. However informally I agree with you in that modulate does not do what it should.
I do agree with you that something is wrong. If you do -modulate 100,0,100, which should desaturate the image, it seems to take the lightest point and make that white. I've been testing on a simple gradient, and both Photoshop and GIMP agree that it should create a gray gradient, not a white to gray one. I also set -colorspace HSL to make sure.
Oh, hehe, I was looking for a dedicated bug tracker
Anyway, I posted a report: viewtopic.php?f=3&t=8854 It should also help you see what I mean, as I added sample images
