Manipulating alpha channel in Photoshop?

[InnocentSausage]

I can't seem to find a way to edit (or at least delete) the alpha channel of an image with transparency in Photoshop.
Ctrl-clicking the thumbnail of the layer and editing it in the channels tab is not what I mean...

Take a gradient, from Red 100% Opacity to Blue 0% Opacity.
After I saved the gradient as a PNG, how can I for example use the levels adjustment on the PNG's alpha channel?

If I open the image in After Effects there is an option to control the alpha channel.
That's quite embarrassing if a video software can edit the alpha channel and an image software can't... :neutral:

I've attached screenshots to demonstrate what I mean.

 

[obliquid]

What exactly are you trying to do? Alpha channels do not contain color. Just black, white and shades of grey...

 

[obliquid]

I just re-read your post. Saving a png does not save alpha channels but it does allow for transparency. Alpha Channels just tell a document where to be transparent and where to be opaque. A png saves the actual transparency (or semi-transparency)

When you open a png in After Effects, it interpolates the alpha channel from the transparency.