cv.jit.stddev Computes the standard deviation of the incoming matrices. Computes the standard deviation of the incoming matrices. The standard deviation is simply the square root of the variance, so the same result can be obtained with cv.jit.variance and a jit.op object. The standard deviation is a measure of how much sample values vary from the mean, or in other words, how wide the distribution on either side of the mean is. About 65% of sample values fall within one standard deviation of the mean, whereas 95% are within twice that value. This measurement is very useful when it comes to setting bounds or threshold values, for instance in a background subtraction operation. If the mean value of a background pixel is 50, and the standard deviation is 10, then a pixel valued at 80 would be considered foreground. However, if the standard deviation is around 30, there is a good chance that it belongs to the background.

from the library : cv.jit Format : External Environment : jitter / max / msp freeware Max 4.x http://www.iamas.ac.jp/~jovan02/cv/download.html