How to deal with premultiplied alpha?

Support Compositing and Post Processing
1

Hi, I recently downloaded some free pack stock footage and when I took a look at it I realised they were .tiff sequences. Now I really don’t know much of premultiplied alpha but I’m sure that’s my problem here: you see whenever I try to open the .tiff’s in any sort of application they show a black and white frame that looks like an alpha matte for the supposed picture.

The pic: https://drive.google.com/file/d/0B8I7vdW7EC1iamxfZjF4WUJRQlk/view?usp=sharing

As I said I don’t know how to deal with premultiplied alpha, is it something I can handle in blenders VSE, compositor or something?

And if it isn’t premultiplication that’s the problem, then what is it? :confused:

Thanks

2

try opening it in a different program, like gimp, then if the alpha channel is active, save as .png

3

Tried it with no luck :frowning:

4

Oh, never mind. I got it work :stuck_out_tongue:

5

Convert alpha node, switch to premult. VSE doesn’t handle it so elegantly.

6

You can “reverse” premultiplication in Blender. It’s an algebraic operation that is standard and can be “un-done.”

7

Tricky to set up separate alpha strip in the vse though.