i'm doing some experiments with violajones algorithm for my digital imaging university course. i need to know how the CvHaarDetectObjects() function, that receives in input a color image, transforms it in a grey scale image. i can't find this information in the documentation and it's hard to find it in the code.
thanks in advance
Antonio Castellano
CvHaarDetectObjects does not convert the img to grayscale.
you've got to do that yourself before, using cvtColor().
and damn, use the C++ api, please!
CascadeClassifier cascade("opencv/data/hairycascades/bald.yml");
if ( cascade.empty())
{
// could not find it
}
Mat img = imread("my.png");
Mat gray;
cvtColor(img,gray,CV_BGR2GRAY);
vector<Rect> faces;
cascade.detectMultiScale(gray,faces);
// process face-rects.
Exactly. C++ code uses C code underneath in most cases, so the C++ API is just a wrapper, which costs performance. It's not much, but depending on your application, you might get a slightly better performance using the C API. And you only get into trouble if you don't know how to use it. But some people do know that and some of them produce even better code with it than with C++.
than you all for the answers. i use the c api because i already know it and i can't spend so much time to learn the cpp api now. as i've understood the function uses one channel of the image. what i son't understand is how the iplimage where i load my images (and can load any type of image) became a 1 channel immage when sent to the function for detection.
Asked: 2013-06-12 04:53:17 -0600
Seen: 892 times
Last updated: Jun 12 '13
