Tracking objects using histogram data in OpenCV - c

Question

I am trying to track objects inside an image using histogram data from the object. I pass in a reference image to get the histogram data and store it in a Mat. From there I load in an image and try and use the histogram data to detect the object. The problem I am coming with is not only is it not tracking the object, but it's not updating the detection. If I load image "1.jpg" the detection will claim that the object is in the top right corner when it's in the bottom left. When I pass in the second image the detection field does not move at all. This continues for the next batch of images as well. Below is a code snippet of my application.
This is being done in a Windows 7 32-bit environment using OpenCV2.3 in VS2010. Thanks in advance for any help
int main( int argc, char** argv )
{
vector<string> szFileNames;
IplImage* Image;
Mat img, hist, backproj;
Rect trackWindow;
// Load histogram data
hist = ImageHistogram("C:/Users/seb/Documents/redbox1.jpg", backproj);
Image = cvLoadImage("C:/Users/seb/Documents/1.jpg");
img = Mat(Image);
trackWindow = Rect(0, 0, Image->width, Image->height);
imshow("Histogram", hist);
while(true)
{
Detection(img, backproj, trackWindow);
imshow("Image", img);
char c = cvWaitKey(1);
switch(c)
{
case 32:
{
cvReleaseImage(&Image);
Image = cvLoadImage("C:/Users/seb/Documents/redbox2.jpg");
img = Mat(Image);
break;
}
}
}
cvReleaseImage(&Image);
// Destroy all windows
cvDestroyWindow("Histogram");
cvDestroyWindow("Image");
return 0;
}
Mat ImageHistogram(string szFilename, Mat& backproj)
{
// Create histogram values
int vmin = 10;
int vmax = 256;
int smin = 30;
int hsize = 16;
float hranges[] = {0,180};
const float* phranges = hranges;
// Load the image
IplImage* Image = cvLoadImage(szFilename.c_str());
Rect rect = Rect(0, 0, Image->width, Image->height);
// Convert Image to a matrix
Mat ImageMat = Mat(Image);
// Create and initialize the Histogram
Mat hsv, mask, hue, hist, histimg = Mat::zeros(200, 320, CV_8UC3);
cvtColor(ImageMat, hsv, CV_BGR2HSV);
// Create and adjust the histogram values
inRange(hsv, Scalar(0, smin, vmin), Scalar(180, 256, vmax), mask);
int ch[] = {0, 0};
hue.create(hsv.size(), hsv.depth());
mixChannels(&hsv, 1, &hue, 1, ch, 1);
Mat roi(hue, rect), maskroi(mask, rect);
calcHist(&roi, 1, 0, maskroi, hist, 1, &hsize, &phranges);
normalize(hist, hist, 0, 255, CV_MINMAX);
histimg = Scalar::all(0);
int binW = histimg.cols / hsize;
Mat buf(1, hsize, CV_8UC3);
for( int i = 0; i < hsize; i++ )
buf.at<Vec3b>(i) = Vec3b(saturate_cast<uchar>(i*180./hsize), 255, 255);
cvtColor(buf, buf, CV_HSV2BGR);
for( int i = 0; i < hsize; i++ )
{
int val = saturate_cast<int>(hist.at<float>(i)*histimg.rows/255);
rectangle( histimg, Point(i*binW,histimg.rows),
Point((i+1)*binW,histimg.rows - val),
Scalar(buf.at<Vec3b>(i)), -1, 8 );
}
calcBackProject(&hue, 1, 0, hist, backproj, &phranges);
backproj &= mask;
cvReleaseImage(&Image);
return histimg;
}
void Detection(Mat& image, Mat& backproj, Rect& trackWindow)
{
RotatedRect trackBox = CamShift(backproj, trackWindow, TermCriteria( CV_TERMCRIT_EPS | CV_TERMCRIT_ITER, 10, 1 ));
int test2 = trackWindow.area();
if(trackBox.size.height > 0 && trackBox.size.width > 0)
{
if( trackWindow.area() <= 1 )
{
int cols = backproj.cols, rows = backproj.rows, r = (MIN(cols, rows) + 5)/6;
trackWindow = Rect(trackWindow.x - r, trackWindow.y - r,
trackWindow.x + r, trackWindow.y + r) &
Rect(0, 0, cols, rows);
}
int test = trackBox.size.area();
if(test >= 1)
{
rectangle(image, trackBox.boundingRect(), Scalar(255,0,0), 3, CV_AA);
ellipse( image, trackBox, Scalar(0,0,255), 3, CV_AA );
}
}
}

Answer 1

I've figured out the issue. It had to deal with me not converting the image that I'm checking upon. I had to get histogram data from my colored box and then I had to get the histogram from the image I was using to search.