mean method
Implementation
Scalar mean({Mat? mask}) {
final s = calloc<cvg.Scalar>();
mask == null
? cvRun(() => ccore.cv_Mat_mean(ref, s, ffi.nullptr))
: cvRun(() => ccore.cv_Mat_mean_1(ref, mask.ref, s, ffi.nullptr));
return Scalar.fromPointer(s);
}