scene strip, no correct alpha in vse

Support Compositing and Post Processing
1

hi. I’m playing around with a green screen and did a simple test footage. Now I’m trying to put one video (scene) over an other one, but no matter what blend type I select, I can’t manage to get a correct transparency. It looks just buggy to me so I don’t know if it’s really my fault or a bug?: The edges around my hand get rendered correctly but everything else with 100% transparency doesn’t, it’s getting rendered as if it was a 50% transparent white area.

the background video is mostly green, so don’t get confused. I read about a bug in 2.76 which had a problem with the ‘add’ blend. Maybe this is related? Because I got the same behavior in 2.76 with the ‘add’ blend but in 2.77a ‘add’ works now however ‘over drop’ or ‘alpha over’ don’t.

Attachments

problem1.jpg1920×1200 313 KB

2

Did you premultiply the compositor output first?

3

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

4

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

5

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

6

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

7

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

8

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

9

No, I didn’t, but that solved the problem. I didn’t know blender uses two different kind of alpha values. Thx.

10

No, I didn’t, but that solved the problem. I didn’t know blender would use two different kind of alpha values. Thx!