PSNR function
Computes the Peak Signal-to-Noise Ratio (PSNR) image quality metric.
https://docs.opencv.org/4.x/d2/de8/group__core__array.html#ga3119e3ea73010a6f810bb05aa36ac8d6
Implementation
double PSNR(InputArray src1, InputArray src2, {double R = 255.0}) {
final p = calloc<ffi.Double>();
cvRun(() => ccore.cv_PSNR(src1.ref, src2.ref, R, p, ffi.nullptr));
final rval = p.value;
calloc.free(p);
return rval;
}