...

diff --git a/MagickCore/compare.c b/MagickCore/compare.c
index 345e7c699a2e2a2e6c53b12e0227839e8e2ddedc..ccc45ecb234e4e0304872d221685f845974c82e5 100644 (file)
--- a/MagickCore/compare.c
+++ b/MagickCore/compare.c
@@ -1239,7 +1239,7 @@ static MagickBooleanType GetPeakSignalToNoiseRatio(const Image *image,
     if (fabs(distortion[i]) < MagickEpsilon)
       distortion[i]=INFINITY;
     else
-      distortion[i]=20.0*MagickLog10(1.0/sqrt(distortion[i]));
+      distortion[i]=10.0*MagickLog10(1.0)-10.0*MagickLog10(distortion[i]);
   return(status);
 }