Convert Mat type to boolean

C++
1

Hi,
how to convert a value Mat (example Mat position = (image,posit)) to bool value?
here is my code lines


vector<Point> posit{Point(row,col)};
if(Mat positition = getPixels(image,posit) ==  image.at<uchar>(row,col))

error → could not convert position to bool?

2

please explain, what you want to achieve here.
what is getPixels() ? and why make such a complicated if clause ?

(already line 1 looks like total bs, as it’s Point(x,y) (wrong order) and even Point(col,row) would probably be out-of-bounds

3

C++ issue. you don’t know the syntax well enough yet.

look up the precedence rules for operators.

also, do not define variables inside of expressions. if that is even possible, it’s a bad idea.

4

The program I’m trying to write aims to replace some pixel’s values according to their coordinates. The error message —> Mat “outp” can not be converted into bool, here is the part of the program

------------------opencv code --------------------

...
Mat image ;
  vector<Point> coor{Point(7,7)}; // --> define a vector with a given coordinates
 Mat outp = getPixels(image, coor);  // --> get the pixel's value 

 for (int row = 0; row < image.rows; row ++) // --> loop through the image
    {
        for (int col = 0; col < image.cols; col ++)
        {                   
             if( outp ==  0 ) // --> if the pixel for the given coordinates equals 0 (black pixel )
             {
               image.at<uchar>(row,col) = 255; // --> replace the pixel with 255 instead of 0
               int pixelValue = image.at<uchar>(row,col);
               outputFile << pixelValue << '\t';

             }
                else {

              int pixelValue = image.at<uchar>(row,col);
              outputFile << pixelValue << '\t';
            }
         outputFile << endl;
5

in OpenCV, single pixels aren’t represented by Mats, but by Vec3b (for uint8 values).

your getPixels function is mysterious.

perhaps you’d have less headache if you just used python. it doesn’t get in your way like C++ does.