Regarding Background this image is just example.
Actual task was to capture the live image from camera and then take background. then do the normalizing image and take intensity profile measurement.
i found the background solution but I don't know how to perform.
this is what i want to do with background
The best way is if you have live control of the light source, either the ability to turn it on/off or block the beam. "You then take a picture (or series of pictures and average them out) of "darkness", i.e. beam off or beam blocked, and then activate the beam, and you subtract the "darkness" image (or averaged images) from each frame with the beam active.
The next-best way is that you subtract a constant value from every pixel. You can either manually pick a value that gives you a nice image, or try to compute it. One way to compute it is to assume certain areas of the screen will always be dark (example: small squares in each of the 4 corners), compute the average light level there (possibly using median intensity instead of mean, so outliers don't shift it too much)."
