How to calculate detection_score for OpenCV's face detector?

Question

I want to use FDDB to evaluate some face detectors including OpenCV. But FDDB's detection output file requires:

<left_x top_y width height detection_score>

It include a detection_score part. But the opencv's detector have no output like this. How to output this?

Answer 1

From their FAQ (http://vis-www.cs.umass.edu/fddb/faq.html)

They define the detection score for a candidate window as:

K*stage_when_rejected + stage_sum_for_stage_when_rejected. (Choosing K as a large value e.g., 1000)

to ensure that windows rejected at stage i have higher score than those rejected at stage i-1