On-line detection of foreign substances in glass bottles filled with transfusion solution through computer vision

In this paper, a real time computer vision system was developed to detect a glass bottle filled with transfusion solution on a packing line. The theory, the mechanical structure, and the detection algorithm are described. Foreign substances mixed in transfusion solution are distinguished from bottle side wall defects by a relative movement between a resting bottle and the inside moving solution. Foreign objects moving down in the bottle are first detected with background subtracting, where a normalized cross correlation is employed to identify two frames between which no moving objects overlap and the static back-ground is obtained through an inter-frame difference. In the second stage, falling objects are recognized through an adapted mean-shift tracker, in which an adaptive searching window is used to only find falling objects. The system was tested on 250-ml transfusion bottles. The result shows that it can effectively detect the small visible foreign substances fulfilling the requirements of the application..