Modulate not the same as Photoshop

[Noogle]

Hi,

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

[Noogle]

Anybody?

[anthony]

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.

[Noogle]

Thanks for your reply

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.

Is there a bug tracker anywhere?

[anthony]

Yes it is called IM bug Forum

[Noogle]

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