diff --git a/src/imageanalyzer.py b/src/imageanalyzer.py
--- a/src/imageanalyzer.py
+++ b/src/imageanalyzer.py
@@ -38,7 +38,7 @@ class ImageAnalyzer:
 
 				I=(red+green+blue)/255/3
 				m=min(red,green,blue)
-				S=1-m/I
+				S=1-m/I if I!=0 else 0
 				if 100*I<self.tresB: b+=1
 				elif 100*I>self.tresW: w+=1
 				else: e+=1