2
$\begingroup$

In Blender Compositor: how can I convert the black in an image to transparency?

Ultimate goal is to add one image A over image B without image A darkening image B.

Improve this question
$\endgroup$
4
  • $\begingroup$ If you really want to add, the you don't need to worry about darkening.. Adding two positive values will always result in a larger value. $\endgroup$
    – gandalf3
    Commented Sep 3, 2014 at 7:16
  • $\begingroup$ I just noticed - inspecting in the image editor - that my images have pixels with color values below 0.0 and above 1.0, this is very strange. Is there no way to clamp the output of Brightness/Constrast node? $\endgroup$
    – VoidStar
    Commented Sep 3, 2014 at 7:26
  • $\begingroup$ What I really want is to replace rather than add $\endgroup$
    – VoidStar
    Commented Sep 3, 2014 at 7:31
  • $\begingroup$ Then the lighten blend mode sounds like what you want. Regarding your first comment, that is part of the fun of working with floating point images :) if you want to clamp it, a quick way to do that is with a multiply mix node. Just make sure the other slot is set to white. $\endgroup$
    – gandalf3
    Commented Sep 3, 2014 at 7:31

1 Answer 1

Reset to default
1
$\begingroup$

What about using a mix node with the lighten blend mode?

enter image description here

If you want more control, then you can generate a grayscale map and use that to set the alpha with a set alpha node:

enter image description here

Improve this answer
$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .