Qimage Color Convert to Gray to grayscale

In Qt, we sometimes need to change the color of the Qimage class to grayscale, at first I was thinking of using the Qimage member function Converttoformat(), but tried a lot of parameters, the return to the conversion of the picture is a problem, not what we want gray-scale image, If you have successfully converted a grayscale image using the member function, please write your method in the comment area and let the blogger learn. Then there is a stupid way, is to manually r,g,b the value of the average, and then use the average to update each pixel value, you can also get a grayscale image. See the code below:

// image is the input color image, IMG is output grey image qimage img (image);  for (int0; i < img.width (); + +i)    {for (int0; j < Img.height (); + +J)        {int gray = Qgray (Img.pixel (i, J));        Img.setpixel (i, J, Qcolor (Gray, Gray, gray). RGB ());}    }

Qimage Color Convert to Gray to grayscale