Adding a png to brushes does not create an alpha

[BradG]

When I import a black and white png image that I want to use to sculpt with, it creates the following maps: all, color, alpha, depth, specl, erase. But I've noticed that only all and color have the actual stamp in it, the others, including alpha are just blank boxes, so when I try to use them with the airbrush, it doesn't do anything. How do I get the program to automatically create an alpha channel as well? I've watched a lot of tutorials that talk about dragging a jpg into the brush panel so I assume it can be done.  

[digman]

You have to make sure that the PNG file has an alpha channel with no information in it.

In my painting software the bottom layer was the alpha channel, Top layer was for the actual painting. I used white. 

Saved the PNG which kept the alpha channel.  Some software asks if you want to include the alpha channel when exporting.

Picture shows the results.  I used it for sculpting in the sculpt room. 

Alpha created not for quality but for workflow informtion. 

Hopefully the above helps.

Side Note: I generally slightly blur my alphas in some cases to remove jaggy edges. I did not blur this one as I was just giving out information.

It is per alpha, some need a slight blur, some don't.