diff --git a/app/src/main/java/xdsopl/robot36/Decoder.java b/app/src/main/java/xdsopl/robot36/Decoder.java
index 88547ca..0143656 100644
--- a/app/src/main/java/xdsopl/robot36/Decoder.java
+++ b/app/src/main/java/xdsopl/robot36/Decoder.java
@@ -331,6 +331,8 @@ public class Decoder {
 		boolean pictureChanged = lastMode != mode
 			|| Math.abs(lastScanLineSamples - scanLineSamples) > scanLineToleranceSamples
 			|| Math.abs(lastSyncPulseIndex + scanLineSamples - pulses[pulses.length - 1]) > syncPulseToleranceSamples;
+		if (pictureChanged)
+			drawLines(0xff0000ff, 8);
 		if (pulses[0] >= scanLineSamples && pictureChanged) {
 			int endPulse = pulses[0];
 			int extrapolate = endPulse / scanLineSamples;