| Hi,
|
| I need to make transparent some zones in an image but not others that have
| the same color. For example if I take logo: image (the ImageMagick wizard),
| I want to turn transparent all white zones but not the white beard.
|
| In other words, I want to make transparent the background of an image but
| not the inner zones that have same color as background is.
|
| I try to use Masking Simple Backgrounds (floodfill) example from Anthony
| Thyssen's example page http://www.imagemagick.org/Usage/channels/
|
| Below the DOS script:
| convert logo: ( +clone -fx "p{0,0}" ) -compose
| ifference -composite -modulate 100,0 +matte difference.png
|
A faster way is to -crop 1x1+0+0 and then use that to tile the original
image!
convert logo: \( +clone -crop 1x1+0+0 -write mpr:bg +delete \) \
\( +clone -tile mpr:bg -draw 'color 0,0 reset' \) \
-compose difference -composite +matte difference.png
| convert difference.png -threshold 0 boolean_mask.png
|
| convert logo: boolean_mask.png +matte -compose CopyOpacity -composite
| logo_boolean.png
|
| but the beard turn transparent...!
|
I suggest you look further down to the method for removing the background
where floodfills are used on the difference image to generate a mask
of what is 'inside' and what is 'outside' an image.
basically you don't -threshold the difference image, but flood fill to
generate the mask.
Anthony Thyssen ( System Programmer ) <[email protected]>
-----------------------------------------------------------------------------
What are the facts? Again and again and again -- what are the _facts_?
Shun wishful thinking, ignore divine revelation, forget what 'the stars
foretell', avoid opinion, care not what the neighbors think, never mind
the unguessable 'verdict of history', -- what are the facts, and to how
many decimal places? You pilot always into an unknown future; facts are
your only clue. Get the facts! -- Lazuras Long, (Aka. Robert Heinlein)
-----------------------------------------------------------------------------
Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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