Alpha Channel Inversion - How?

Software G'MIC
1

Hello
How do I invert the alpha channel in a PNG?
Tnx a lot!

2

I’d say :

$ gmic input.png to_rgba s c,-3 negate. 255 a c output output.png

EDIT: Well, this one is shorter (but probably a bit slower):

$ gmic input.png to_rgba f. "[R,G,B,255-A]" output output.png

This one is even shorter (and faster) :

$ gmic input.png to_rgba sh 3 negate. rm. output output.png

Plenty of possibilities :slight_smile:

3

I would go with this:

$ input.png to_rgba sh 3 negate. 255 rm. output output.png