[magick-users] Mathematical Cloud Composition

[Anthony Thyssen]

"Ashton Peters" on  wrote...
| Interstingly enough, I found the following on my machine (Vista, Core 2 
| Duo):
| 
| (r+g+b)^2/3^2    = 28 seconds
| 
| (r+g+b)*(r+g+b)/9.0    = 40 seconds
| 
| (r+g+b)^2/9.0    = 22 seconds
| 

The image is grey-scale.   so only one channel needs to be worked on!

  convert nzcloudstc9.jpg -channel R -fx 'r^2' -separate \
           squared_clouds.png

But then why are you mucking around with slow FX when you can use the
bulti-in image composition!!!!

  convert nzcloudstc9.jpg \( +clone \) -compose multiply -composite \
          squared_clouds.png

This runs in 2 seconds, most of which is probably disk IO!
and my machine is NOT very fast!

A lot of tasks that -fx can do, can also be done by builtin options
such as    -evaluate   -compose/-composite   -distort
and as these do not interpret a string expresion over and over, they
are a lot faster.

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