Is there a way to extract the alpha channel from a transparent png file?
I would like to use the 8 bit grayscale of that png.
In the picture object the mask is nil. So, it is not stored there… where is it? 
if you load it in xojo, you can check if it has a mask and use the mask.
(or first convert it into a picture with mask)
or if you need bytes use PictureReaderMBS class.