Comments (2)
Hello, it's inverted all the bands. If you want to just invert RGB and leave alpha alone, you'll need to break off the alpha and reattach it.
#!/usr/bin/python
import sys
import pyvips
x = pyvips.Image.new_from_file(sys.argv[1])
alpha = x[-1]
x = x[0:x.bands - 1]
x = x.invert()
x = x.bandjoin(alpha)
x.write_to_file(sys.argv[2])
Now:
$ ./invert-rgba.py head.png x.png
Makes:
You could also use linear()
to apply a different linear transform to each channel like this:
x = pyvips.Image.new_from_file(sys.argv[1])
x = x * [-1, -1, -1, 1] + [255, 255, 255, 0]
x.write_to_file(sys.argv[2])
This probably seems a bit odd. libvips started as a scientific image processing library, so it really just sees images as huge arrays of numbers. Things like alpha channel support are much later additions and are generally not automatic.
from pyvips.
Thanks, it worked! 😃
from pyvips.
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