Question

I’m using opencv2 c++ interface.

I want to understand how convert color from Scalar to float. I have a matrix like this:

d = Mat(src.rows, src.cols, CV_32F);

and I want to fill some part of it with a color represented in a Scalar with RGB 255 value:

for(int i=0; i<src.cols*src.rows; i++)
    if (some_condition)
        // fill it with red
        d.at<float>(i/src.cols, i%src.cols) =? Scalar(255,0,0);

Answer 1

For converting some elements of a float cv::Mat check this method of cv::Mat class

   // sets some of the matrix elements to s, according to the mask
   Mat& setTo(const Scalar& s, const Mat& mask=Mat());

http://opencv.willowgarage.com/documentation/cpp/basic_structures.html

You should define a mask that defines which parts of your matrix satisfy the condition of your if statement.