More results ...

This technique works regardless of the color of the line ... as long as the line can be well differentiated from the background we can detect it!

It even works if we reverse the original black line on white tile assumption.

In fact, we don't really even need a connected line!

Here is a case where the end of the line is reached. Notice that the COG has fallen below the center of the screen. Perhaps we can use this condition to stop the robot!

Opps, a mistake! The robot will start following the wrong line ... but there again no technique is perfect.