Exporting to PNG with alpha

[BONES]

PNG is my "go-to" bitmap format and I am not aware of any application that supports greyscale + alpha. I just checked 3DS MAX, Combustion and Toxik and they only support alpha with RGB. I'm at work so I can't check Corel but it's not an option I've ever noticed if it is there.

[steve.ledger]

In the absence of an answer to my previous question.
What's wrong with simply turning your image into greyscale, then using Xtremes transparency tool and exporting as true color+alpha?
You are not adding any color, but you are acheiving your goal of a photo/image made up of varying tones of black and white with an alpha transparency.
As for bytes, well this depends. My example below show some increase in kb, but hardly worth worrying over.

8bit greyscale : 54.6 KB


32bit with alpha : 59.2 KB