IMAQ image overlay with alpha blending (partial transparency) ?

[jbeale1]

 I am using Labview 2014 on Win7. I have found examples of color image overlay with binary transparency (A + B = OUTPUT with each output pixel either 100% image A or image B) but have not found any examples of alpha blend (partial transparency). For example, some output pixels are (20% A + 80 % B).   Can I do that in LabView?

IMAQ ArrayToColorImage VI takes U64 image pixels as clusters of 4 unsigned 16 bit values, interpreted as Red, Green, Blue, and Alpha planes.  Is there any VI that makes use of the 4th plane (alpha) to do alpha blending when combining two bitmaps?

IMAQ Overlay Bitmap VI comes with the note "This VI does not support alpha blending." Is there any other VI which does support alpha blending?

[AgentAstronaut · Accepted solution]

Hi jbeale1,

IMAQ does not display transparency. It maintains the alpha channel but does not do anything with it.

If you want to mimic alpha transparency blending manually here is a page about doing just that:

http://www.ni.com/example/26682/en/ 

I hope this clarifies some things.

Michael

[jbeale1]

I was afraid of that, but thanks for confirming it. The example shows a single color value; I wish there was alpha blending channel support for IMAQ images.  Maybe it takes too much CPU power to work with typical video resolution & frame-rate, though.