[magick-users] Need help with -modulate

[Fred Weinhaus]

I believe that -modulate was changed to use BSH rather than LSH color 
model. See the discussion at
http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=12640&hilit=modulate. 
I don't know if there is an option to get backward compatibility (or 
if this change really took place).

See also Anthony's notes about the problems with HSL vs HSB (HSV) 
color models at http://www.imagemagick.org/Usage/color/#modulate

You can do a Google search to learn more about these two color 
models. The first is a double hexcone model and the second is a 
single hexcone model. see also 
http://en.wikipedia.org/wiki/HSL_and_HSV

Using your second image and playing around, seems like you need to 
control the saturation and not the brightness (or both). So the best 
I got was about

-modulate 95,220

Try that and  play around. The second number is the saturation which 
needed to be drastically increased to get close to what you had from 
before. It also needed a bit decrease in brightness.


>Hi.  I need some help using the -modulate option.  I use modulate to
>"clean up" some dirty looking scans that my old scanner produces.
>After I upgraded to Ubuntu Jaunty (imagemagick version 6.4.5)  I
>noticed that the behavior of -modulate changed.  The command I'm using
>is basically this:
>
>convert original.tiff -flatten -depth 8 -modulate 140 new.jpg
>
>Imagemagick version 6.3.7 in Ubuntu Intrepid produced the following:
>
>http://home.hiwaay.net/~gentlec/20090613-160502.jpg
>
>After upgrading to 6.4.5 in Jaunty I now get this:
>
>http://home.hiwaay.net/~gentlec/20090613-160105.jpg
>
>I'm definitely not an imagemagick expert.  If the -modulate command
>has changed, is there any way for me to reproduce what it was doing in
>earlier versions?
>
>Thanks!