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OpenCV face detection in iPhone

asked 2012-09-24 21:02:44 -0500

Thomas_N gravatar image

updated 2012-09-25 06:01:01 -0500

Kirill Kornyakov gravatar image

Dear All,

I implement OpenCV face detection in iPhone 4. When I look at the time taken for the implementation of the function

face_cascade->detectMultiScale(*grayMat, faces, haar_scale,
                                   haar_minNeighbors, haar_flags, haar_minSize );

It takes nearly 120msec. I can't tolerate that amount of time for my application. How can I improve the performance to reduce the processing time? My configurations are:

float haar_scale = 1.15;  
int haar_minNeighbors = 3;  
int haar_flags = 0 | CV_HAAR_SCALE_IMAGE | CV_HAAR_DO_CANNY_PRUNING;  
cv::Size haar_minSize = cvSize(60, 60);

Thanks.
Thomas

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answered 2012-09-25 06:37:06 -0500

Kirill Kornyakov gravatar image
  1. Try to use LBP features instead of Haar. It may give you ~3x speedup. Cascade file for the LBP face detector is available in the OpenCV repository.
  2. Try to increase haar_minSize parameter, because it greatly affects the speed.
  3. Right now you can try CV_HAAR_FIND_BIGGEST_OBJECT, on mobiles it is sometimes true that you need only the largest face.
  4. You can also try to use DetectionBasedTracker class which does tracking. It greatly reduces apparent processing time, because slow detection is performed in a background thread.
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Asked: 2012-09-24 21:02:44 -0500

Seen: 1,227 times

Last updated: Sep 25 '12