Face Detector Parameters for OpenCV cv_haar_scale_image

Question

What does cv_haar_scale_image do in opencv's function cvhaardetectobjects?

Answer 1

It enables more optimization.

The face detect implementation is optimized for CV_HAAR_SCALE_IMAGE more than CV_HAAR_DO_CANNY_PRUNING.

Because CV_HAAR_SCALE_IMAGE method is more DMA (direct memory access) friendly. Default method (CV_HAAR_DO_CANNY_PRUNING) implementation needs random access to main memory area widely.