David Vanderson on wrote...
| Hello,
|
| A few weeks ago we were doing cloud composition, which is close to
| something that I've been doing - setting the alpha channel of each pixel
| to the intensity of each pixel. Anthony asked why we were using -fx,
| which is slow, instead of -evaluate.
|
| I confess that I've tried and failed a few times to figure out how to do
| this with -evaluate. Can anyone enlighten me?
|
| Thanks,
| Dave
Note -channel A -fx intensity
was being used to mapp a greyscale to the alpha channel.
Try this instead.
convert image.png -colorspace gray \
-background white -channel A -combine ouptut.png
This command makes the input image greyscale.
It then makes that greyscale image a 'transpaency' channel setting
all other color channels to pure white. That is it is now a white
image with various shades of transparency.
If this is NOT what you want, then me more specific.
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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Kite(n): An offering to the wind gods proffered on a line that
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Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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