Yes, I am aware of that. But extracting the alpha channel from the .DDS compressed format isn't something Image Kit is able to do either (it was designed to operate on images, but not to retreive information from them).
In any case, Image Kit can't give you the alpha channel values directly. Maybe it would be possible using a workaround though.
- Make a bitmap that fits the image
- Clear the bitmap with a white color
- Make the image color components black by using a brightness parameter of 0.0 (you only need to do this for one component - R, G or B).
- Paste the image on the bitmap. (Optional explanation: )
By doing this, the resulting color will be:
R = B * (1 - a) + T * a
where B = bottom color, T = top color. The bottom was white because we cleared the bitmap (B = 1), whereas the top was made black using the brightness command (T = 0), so you get
R = 1 - a
Which makes it pretty easy to work out.
The resulting color will give you the alpha value:
a = 1 - C, where C is the R, G or B channel (it doesn't matter which one you choose).
Note: You will probably need to use
a = 255 - C instead since color component values are usually expressed as bytes.
I'm not sure if you can turn that bitmap into a memblock to get the color values. I'm starting to lose my touch with DBP, but if that doesn't work then you can still retrieve the pixels using the point() command (or you can search for faster alternatives).
So to summarize:
Make a bitmap white
Make the image black (and be careful not to touch the alpha channel)
Paste image
Get pixel color
a = 255 - color
Cheers!
Sven B
