Learning OpenCV, 2nd Edition

shadow). The default value for this parameter is 0.50. Finally, the setShadowValue() function is used

if you want to change the numerical value assigned to shadow pixels in the foreground mask. By default,

background will be assigned the value of 0, foreground the value of 255, and shadow pixels the value of

127. You can change the value assigned to shadow pixels using setShadowValue() to any value

(except 0 or 255).

8BSummary

In this chapter, we looked at the specific problem of background subtraction. This problem plays a major

role in a vast array of practical computer vision applications, ranging from industrial automation, to

security, to robotics. Starting with the basic theory of background subtraction, we developed two basic

models of how such subtraction could be accomplished based on simple statistical methods. From there we

showed how connected component analysis could be used to increase the utility of background subtraction

results and compared the two basic methods we had developed.

We concluded the chapter by looking at the more advanced background subtraction methods supplied by

the OpenCV library as complete implementations. These methods are similar in spirit to the simpler

methods we developed in detail at the beginning of the chapter, but contain improvements which make

them suitable for more challenging real-world applications.

9BExercises

1. Using cv::accumulateWeighted(), re-implement the averaging method of background

subtraction. In order to do so, ...