Op maandag 25 augustus 2008, schreef Gilles Sadowski:
> $ convert test.png -transparent white test_tr.png
This will convert 'white' to '100% transparent', but not the shades of grey
created by the anti-aliasing algorithms in ghostscript.
After long fiddling I found a way to convert every shade of grey to black with
a corresponding percentage of transparency:
convert input.png \
-trim -bordercolor white -border 3 \
\( +clone -threshold 100% \) \
\( -clone 0 -negate \) \
-delete 0 -compose CopyOpacity -composite +repage output.png
- the first line crops the image and adds a border of 3 pixels
- the second and third line create to new images, one just black, the other
with the colors negated.
- the last line deletes the first (original) image and copy the negated image
to the alpha channel of a fully black image.
I use this to create LilyPond symbols for the menu actions in LilyKDE :-)
best regards,
Wilbert Berendsen
--
LilyKDE, LilyPond for KDE: http://lilykde.googlecode.com/
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