Is it possible to run the CascadeClassifer without preprocessing?

asked 2016-11-30 05:36:30 -0600

DerrickB
26 ●1 ●5

updated 2016-11-30 05:37:32 -0600

Hello OpenCV Community,

is it possible to run the CascadeClassifier without the Preprocessing (Sliding Window and Image Pyramid). I mean i want to give really small image fragments as input (e.g. 24x24) and the Classifier should just say positive or negative.

If i put the ScaleFactor and minSize of the multidetect method to "1" and minSize to "24x24" the method crashes.

This is for research and performance test.

Thank you very much,

Kind regards,

Derrick

answered 2016-12-05 03:13:34 -0600

pi-null-mezon

536 ●2 ●13

Hello. First, scale factor should be greaer than the 1.0, it is pretty evident because CascadeClassifier::detectMultiScale function uses this value to calculate the ammount of the scale steps (so for 1 it is infinite, so your code crashes because of memory consumption). Second, of cource you can detect without any scale and shift, use CascadeClassifier::setImage and CascadeClassifier::runAt

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i cant find the methods "setImage" or "runAt". I think they are private or something???

DerrickB ( 2016-12-12 04:25:25 -0600 )edit

Sorry, it seems that this docs are outdated. In actual API you should use detectMultiScale with options. For the instance if you have WxH _image with region of interest 24x24 than do:

cv::Mat _roimat(_image, cv::Rect(_targetX,_targetY,24,24)); // manually select the roi region 
std::vector<cv::Rect> _vrects; // this vector will store the detector's output
_cascadeclassifier.detectMultiScale(_roimat, _vrects, 1.1, 3, 0, cv::Size(24,24), cv::Size(24,24));

pi-null-mezon ( 2016-12-12 12:33:14 -0600 )edit

Yes with this solution it works, thanks!

DerrickB ( 2016-12-16 06:28:38 -0600 )edit

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