So what is the truth about PNG alpha channels?
google yields many photoshop forum posts declaring that “PNGs have no alpha channel, they only have transparency”
But I take this mean only that photoshop and most display programs only ever treat PNG alpha as transparency.
Pngs (at least png 24+transperency) must be RGBA images by my understanding.
Is there a way to manipultate the alpha in a png in more general ways
-like baking a greyscale texture map into it , etc?
or is there truly something unusual about png alpha that makes it impossible to treat them as flexibly as you might a 32 bit TIF or BMP?