Background subtraction

is there a pixel shader background subtraction that is extremely sensitive. I am working with blob detection and i am looking to use the device in the light, where there is a noticable difference between the blobs, but it is extremely fine. Please let me know the best way to remove the background. I have already tried background subtraction.fx and the pixel shader difference between 2 textures, and them in conjunction with one another. Thanks

any ideas?

how fast are your objects changing? is your background changing? is your camera moving? what kind of camera (composite, fw, usb, bw, ir) are you using? how are light conditions? is there any way to improve the camera optics, light conditions, scene geometry?

software-wise you can try using more than one background images, and average them before subtracting them. in vvvv you could setup a patch, which feeds the (e.g.) last 4 frames in the shader (create four texture input pins in the shader) and average the oldest three and subtract the newest. but i am not an image processing expert - there might be more clever ways (splines, polynoms, convolutions whatever) to get the most of history.

they are moving pretty slow, its for a multi-touch input. the background is constant, and the camera is fixed. its a usb camera, with an ir bandpass filter. i can’t really change the ir level of the room.

ah. sory i only read now…you already use IR-lighting (wasn’t sure in the other posting).

so then there are cameras that are more sensitive to IR than others. i was told that the point grey cameras are pretty strong in IR.