c++ - Why does Cascade return so many faces? -

i'm trying learn opencv examples, i've met big problem objectdetection.cpp. ran on laptop, returns me huge number of faces in first run , not continue run round in while. has encountered before?

before defect:

after defect:

• try this.may you.

  face_cascade.detectmultiscale(frame_gray, faces, rejectlevels, levelweights,         1.1, 3, 0 | cv_haar_scale_image, size(16, 16), size(0, 0), true);