stationary particles romoval

[Sergey(PSU)]

Lets imagine we are measuring the size of the moving stream of particles. Some of them or just a dirt particle that sticks to the window surface and is counted almost every time(image).

Is there VI or what would be the suggestion how to exclude static particles from statisctics(analysis).

[BruceAmmons · Accepted solution]

Are you using grayscale or binary images?

For binary images, you could keep several old images and use AND to combine them into a mask.  The mask could be inverted and then AND it with the current image.  Only stationary particles would be in the same place in all of the images.  I would probably store a circular buffer of ten images.  I would replace the oldest image about once per second, then regenerate the mask from the ten images.  This would only keep stationary particles that have not moved in the last ten seconds.

If you are post processing, you could get a little fancier.  You could create the mask by combining some images before and after the current image.  This could be a tighter window, maybe one second before and after, to identify stationary particles.  The ideal spacing between reference images will depend on particle size, particle speed, and possibly other factors.

For grayscale images, you could use MIN to combine images instead of AND, assuming white particles on a black background, then subtract the mask image from the current image to remove the stationary particles.

Bruce