Here is the CPU version of a function
void getContourCenters(vector&framesToProcess, vector& contourCenter)
{
size_t j = 0;
for (int i = 1; i < framesToProcess.size(); i++)
{
Mat tempDifferenceImage, tempThresholdImage;
vector< vector> contours;
vector hierarchy;
Rect objectBoundingRectangle = Rect(0, 0, 0, 0);
absdiff(framesToProcess[i - 1], framesToProcess[i], tempDifferenceImage);
threshold(tempDifferenceImage, tempThresholdImage, SENSITIVITY_VALUE, 255, THRESH_BINARY);
blur(tempThresholdImage, tempThresholdImage, Size(BLUR_SIZE, BLUR_SIZE));
findContours(tempThresholdImage, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
cout << "Time to findContours: " << t1.elapsed() << endl;
t1.restart();
for (int k = 0; k < contours.size(); ++k)
{
objectBoundingRectangle = boundingRect(contours[k]);
int xpos = objectBoundingRectangle.x + objectBoundingRectangle.width / 2;
int ypos = objectBoundingRectangle.y + objectBoundingRectangle.height / 2;
contourCenter.push_back(mp(xpos, ypos, j++));
}
}
}
This function takes about 1.5 seconds to execute for 30 grayscale images. Now I optimized this code for GPU
void getContourCenters(vector&framesToProcess, vector& contourCenter)
{
size_t j = 0;
for (int i = 1; i < framesToProcess.size(); i++)
{
gpu::GpuMat tempDifferenceImage, tempThresholdImage, tempBlurredImage;
vector< vector> contours;
vector hierarchy;
Rect objectBoundingRectangle = Rect(0, 0, 0, 0);
gpu::absdiff(framesToProcess[i - 1], framesToProcess[i], tempDifferenceImage);
gpu::threshold(tempDifferenceImage, tempThresholdImage, SENSITIVITY_VALUE, 255, THRESH_BINARY);
//If i comment following line the function works fine and executes in 0.5 second but if I uncomment
// following line it takes more than 30 seconds to execute the function
gpu::blur(tempThresholdImage, tempBlurredImage, Size(BLUR_SIZE, BLUR_SIZE));
Mat contourImage( tempBlurredImage );
findContours(contourImage, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
for (int k = 0; k < contours.size(); ++k)
{
objectBoundingRectangle = boundingRect(contours[k]);
int xpos = objectBoundingRectangle.x + objectBoundingRectangle.width / 2;
int ypos = objectBoundingRectangle.y + objectBoundingRectangle.height / 2;
contourCenter.push_back(mp(xpos, ypos, j++));
}
}
}
The GPU version of code takes about 0.5 second to execute when the function gpu::blur is commented but if this line is uncommented it takes more than 30 seconds or sometimes more ( i don't have that much patience so i kill the process ) . Can anyone point what is the problem with this code? Thank you in advance.
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