Linear space and alpha channel output

[Darby Edelen]

I’m sorry, I think you’re missing the forest for the trees.

The only reason to have transparency is to blend the image over another image.

What I’m telling you is that the blending operation itself is color space and gamma independent. Only the colors involved in the blend are dependent on the color space and gamma. Alpha values should never change between color spaces, the alpha is not a color, it is a weighting for the blend operation. Which, as I’ve already said, does not depend on color space or gamma.

I think you need to provide a concrete example of why you want the alpha to change its values when rendering from linear to gamma encoded. Are you trying to preserve the look of a linear blend? If so then modifying the alpha will never get you there*. If not, then there’s no reason to work in linear to begin with.

*Except in the special case of blending pure colors (100% or 0% intensity in all channels) with white or black.

Darby Edelen

[Andrew Somers]

I’ve already provided concrete examples, as I stated: text, fades, and transparent drop shadow. But I don’t seem to be getting the point across to you, as you are bringing up separate (and not directly related) issues.

At some point when I have time I will provide the workflow reasons with examples. Until then I’ll table the discussion as we aren’t getting anywhere.

[Darby Edelen]

This is frustrating as I’m sure we could arrive at a mutually agreed conclusion in a matter of minutes if we were talking face to face in front of AE.

[Andrew Somers] “But I don’t seem to be getting the point across to you, as you are bringing up separate (and not directly related) issues.”

This is an interesting observation. If your perceived issue is transparency then I don’t see how the alpha blending operation could be separate from the discussion. Any transparent image is always being blended. It may be blended with the default checkerboard pattern or another default colored background, but the blend and the transparency are inextricably linked and I would argue that they cannot be considered separately. They’re two sides of the same coin.

Darby Edelen

[Darby Edelen]

Andrew, if you ever found time to collect some workflow examples I’d love to take a look at them.

Darby Edelen

[Darby Edelen]

[Andrew Somers] “At some point when I have time I will provide the workflow reasons with examples. Until then I’ll table the discussion as we aren’t getting anywhere.”

Have you found any time to share some examples?

Darby Edelen

[Darby Edelen]

[Andrew Somers] “At some point when I have time I will provide the workflow reasons with examples. “

I realize it’s been several months, but I’m still very much interested in seeing your examples.

Darby Edelen