How to change or discard alpha channel

yar · October 26, 2021, 6:32pm

How to change or discard alpha channel without a premultiplication? From png file for example

It doesnt work because of multiplication at some point

joreg · October 29, 2021, 11:42am

please share a patch and a .png with alpha channel to show this.
also please show us what you’re expecting to achieve.

yar · November 1, 2021, 4:35pm

@joreg I wouldn’t say it’s very relevant, but it’s an interesting question. Here is the file, it has RGB, but the alpha is zero. How do I get RGB in opencv or skia? I feel like it’s already more relevant to do it through fuse, but still.

And this is png
A 2 (0-00-00-00).zip (5.5 KB)

joreg · November 10, 2021, 4:36pm

the opencv ImageReader has options to read the file. if i choose the AnyColor flag, i get an RGB-only image:

indeed, in skia i don’t seem to find such an option.