[C#]
Canvas canvas = new Canvas(Server.MapPath("rez/transparent.png"));
canvas.TransformColors(XColorMatrix.MakeAlphaToGray());
canvas.SaveAs(Server.MapPath("TransformColors_107.jpg"));
[Visual Basic]
Dim canvas As New Canvas(Server.MapPath("rez/transparent.png"))
canvas.TransformColors(XColorMatrix.MakeAlphaToGray())
canvas.SaveAs(Server.MapPath("TransformColors_107.jpg"))
The above reads a PNG with transparency and extracts the alpha
channel as a gray intensity map. The input and output files are
shown below.

transparent.png

TransformColors_107.jpg
|