Parallel implementation of per pixel calculations
Hi,
I am using OpenCV 3.0 .
In my serial implementation I use the Mat_::iterator quite often to access and edit each pixel of an image (As in the example below).
What is the best practice to accelerate these calculations ?
Unfortunately I cannot find ways to access particular pixels in a UMat matrix.
Mat createFGMask(Mat &depthMap){
Mat fgMask = depthMap.clone();
// obtain iterator at initial position
Mat_<uchar>::iterator it= fgMask.begin<uchar>();
// obtain end position
Mat_<uchar>::iterator itend= fgMask.end<uchar>();
// loop over all pixels
for ( ; it!= itend; ++it) {
//IF VALUE GREATER THEN 120, SET TO FOREGROUND ( ie. 1):
if( (*it)> 120 ) (*it)=255;
else (*it)= 0;
}
return fgMask;
}
A more complex scenario where values of each pixel is required:
Mat pixelShifting(Mat &refImage, Mat &depthValue, ){
Mat warpedImage = Mat::zeros( 768, 1024, CV_8UC3 );
int height = refImage.rows;
int width = refImage.cols;
double newX, newY;
Mat newCoord;
for( int col = 0; col < refImage.cols; ++col ){
for( int row = 0; row < refImage.rows; ++row ){
//FIRST SHIFT BACKGROUND PIXELS:
if( depthValue.at<uchar>(row,col) <= 120 ){
newCoord = calcNewCoord(col, row, depthValues.at<double>(row,col)); // ALGORITHM THAT COMPUTES
// NEW PIXEL COORDINATES
COORDINATES.
newCoord = calcNewCoord(col, row, depthValues.at<double>(row,col));
newX = roundCoord(newX);
newCoord.at<double>(0, 0);
newY = roundCoord(newY);
newCoord.at<double>(1, 0);
if( 0<= newY < height && 0<= newX < width ) {
warpedImage.at<Vec3b>(newY, newX) = refImage.at<Vec3b>(row, col);
}
}
}
}
return warpedImage;
}
This code basically takes 2 images, and populates a 3rd image with pixels of image1 by calculating new coordinates using values from image 2.
