The same image brings different result. Can anybody explain this?

Hi. Thank you for watching.
I’m totally confused dealing with alpha things.

light.blend (1.13 MB)
In the file, there are nodes called A and B. Both of them has the completely same image (color and alpha). You can confirm that by doing ctrl shift left-click them using node wrangler add-on.

However, if you alpha over them with the other image, the result differs completely.
Can anybody explain how this happens?:frowning:




In the Alpha Over node enable the ‘Convert Premul’ option