[magick-users] gradient to transparency

[Anthony Thyssen]

Bob Meetin on  wrote...
| I see what you noted with .gif.  However, I was also generating a .png 
| version with the same problem. gradient:anything-none is producing the 
| same output, i.e.  == gradient:anything-anything.   Regardless of the 
| color, it is not recognizing "none".  So curious, I checked on another 
| hosting server with the same result.  Well now, even more curious I 
| tested command-line on my Fedora Linux box and this time it works.  So 
| the version of ImageMagick installed on the server is the culprit I guess.
| 
| What I am showing for version is:  *Version: ImageMagick 6.0.7 04/19/08 
| Q16 http://www.imagemagick.org Copyright: Copyright (C) 1999-2004 
| ImageMagick Studio LLC
| 
In IM examples WARNING note...

=======8<--------
Before IM v6.2.9-8 you would have to resort to using a greyscale gradient as an
alpha channel mask to a solid color image, to produce the same effect. See
'CopyOpacity' composition method, and Using Masks with Images for such
techniques.
=======8<--------

So yes the installed version is to old.  You will have generate a
gradent transparency mask, and merge it into your solid color canvas.

See http://imagemagick.org/Usage/channels/#masks


Also not that in IM 6.3.1  the gradients were changed to produce a perfect
gradient with the same color value across each row.  Before this there was a
slight horizontal gradient over each row before continuing into the next row.


  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
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