Fixed incorrect formula

Author: CodeByDrescher

vcell-cli/src/test/java/org/vcell/cli/run/plotting/TestResults2DLinePlot.java

@@ -169,7 +169,7 @@ public void pngRoundTripTest() throws IOException {
         Assertions.assertEquals(originalImage.getWidth(), roundTrippedImage.getWidth());
         Assertions.assertEquals(originalImage.getHeight(), roundTrippedImage.getHeight());
         double accuracy = TestResults2DLinePlot.getAccuracyPercentage(originalImage, roundTrippedImage);
-        Assertions.assertTrue(accuracy > ACCURACY_THRESHOLD, String.format("accuracy: %f !> %f", accuracy, ACCURACY_THRESHOLD));
+        Assertions.assertTrue(accuracy > ACCURACY_THRESHOLD, String.format("accuracy: %f !> %f; file: %s", accuracy, ACCURACY_THRESHOLD, dupe.getCanonicalPath()));
     }
 
     @Test

vcell-cli/src/test/java/org/vcell/cli/testsupport/SSIMComparisonTool.java

@@ -75,10 +75,10 @@ private double luminanceCalculation(double originalPSM, double contenderPSM){
     }
 
     private double contrastCalculation(double originalVariance, double contenderVariance){
-        double ovSquared = originalVariance * originalVariance;
-        double cvSquared = contenderVariance * contenderVariance;
-        double numerator = 2 * originalVariance * contenderVariance + this.CONTRAST_STABILIZER;
-        double denominator = ovSquared + cvSquared + this.CONTRAST_STABILIZER;
+        double originalSD = Math.sqrt(originalVariance);
+        double contenderSD = Math.sqrt(contenderVariance);
+        double numerator = 2 * originalSD * contenderSD + this.CONTRAST_STABILIZER;
+        double denominator = originalVariance + contenderVariance + this.CONTRAST_STABILIZER;
         return numerator / denominator;
     }