Split RGB+alpha and compose back
Posted: 2014-04-04T13:14:57-07:00
I'm getting a little crazy here...
I want to do simple thing.
1. split my transparent PNG into 2 images - RGB + grayscale alpha
(do something)
2. compose them back
So, for now I don't do anything between steps 1 and 2, but it doesn't work.
My code is:
This part is ok. I get RGB without transparancy and alpha channel as a grayscale image.
But when I try to combine them back, I loose all my semi-transparent pixels:
I want to do simple thing.
1. split my transparent PNG into 2 images - RGB + grayscale alpha
(do something)
2. compose them back
So, for now I don't do anything between steps 1 and 2, but it doesn't work.
My code is:
Code: Select all
convert in.png -channel Alpha -separate a.png
convert in.png -channel alpha -threshold 100%% +channel rgb.bmpBut when I try to combine them back, I loose all my semi-transparent pixels:
Code: Select all
convert rgb.bmp a.png -alpha off -compose CopyOpacity -composite PNG32:result.png