1、计算图像中像素非零个数, 函数 int countNonZero( InputArray src )，单通道图像。

1 int val=countNonZero(img)//返回值为图像img所有不为0的像素

2、返回图像src像素的平均值,Scalar mean(InputArray src, InputArray mask = noArray());

Scalar val= mean(src);

3、返回像素不为0的平均值，float ImageNoZeroMean(Mat img)

 1 float ImageNoZeroMean(Mat img)
 2 {
 3     int c = img.cols;
 4     int r = img.rows;
 5     int val = r * c;
 6     int a = countNonZero(img);
 7     Scalar b = mean(img);
 8     double Imgmean = b[0] * val / a;
 9     return Imgmean;
10 
11 }
 1 float ImageNoZeroMean(Mat img)
 2 {
 3     int c = img.cols;
 4     int r = img.rows;
 5     int val = r * c;
 6     Scalar b = sum(img);//所有像素总和
 7     double Imgmean = b[0] /val;
 8     return Imgmean;
 9 
10 }