CODEWITHSUNDEEP
imagemagickimagemagick-convert
user2183336
user2183336

Reputation: 655

ImageMagick kmeans with alpha transparency

I want to apply kmeans to an image with an alpha mask. It should only work on the colors that are visible. I'm hoping to one-line it. Starting image:

SpaceshipTransparency.png

Naively apply kmeans (whoops, all one color):

convert SpaceshipTransparency.png -kmeans 12x20 KmeansOnly.png

KmeansOnly.png

Experiment. Run through all alpha choices. -alpha remove seems to work somehow but it has a white background? Need to remove this and I found a three step process on ImageMagick docs by outputting a mask as a middle step:

convert SpaceshipTransparency.png -alpha Remove -kmeans 12x20 AlphaRemove.png
convert SpaceshipTransparency.png -alpha extract mask.png
convert AlphaRemove.png mask.png -alpha Off -compose CopyOpacity -composite ThreeStepProcess.png

ThreeStepProcess.png

Upvotes: 0

Views: 114

Answers (1)

fmw42
fmw42

Reputation: 53174

You can combine commands by chaining using parenthesis processing and in-memory (MPR:) images in Imagemagick.

Try:

convert SpaceshipTransparency.png -write mpr:img +delete \
\( mpr:img -alpha Remove -kmeans 12x20 \) \
\( mpr:img -alpha extract \) \
-alpha Off -compose CopyOpacity -composite OneStepProcess.png

Note: -kmeans is only available on Imagemagick 7. So I recommend using magick rather than convert.

Upvotes: 1

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