How do I substract an image at the time t with an image at t-1 to detect move in a grab acquisition

[faux francis]

After the VI acquire in a grab acquisition, how do I substract an image at the time t with an image at t-1 to detect the movement in the scene?

[Yusuf C]

Hello,

One way of doing that is to do a ring acquisition with two buffers. At anytime one of your buffers will be the most current frame and the other will be one before the most current. Having both buffers available at anytime in your code you can call IMAQ Subtract.
Hope this helps!

Yusuf C.
Applications Engineering
National Instruments