Set min value of frame rate reduction to 1

src/main/java/org/mastodon/mamut/segment/ui/SegmentUsingEllipsoidsView.java

@@ -32,7 +32,7 @@ public class SegmentUsingEllipsoidsView implements Command
 	private String option;
 
 	@SuppressWarnings("unused")
-	@Parameter(label = "Frame rate reduction", description = "Only use every n-th frame for segmentation. 1 means no reduction.")
+	@Parameter(label = "Frame rate reduction", description = "Only use every n-th frame for segmentation. 1 means no reduction. Value must be >= 1.", min = "1")
 	private int frameRateReduction;
 
 	@SuppressWarnings("unused")