1. A method of distinguishing between text strokes and non-text strokes in digital ink, the method comprising: detecting a gap between a first stroke and a second stroke in the digital ink; generating a classification model based on at least one gap feature of the gap, wherein the model defines a posterior probability of the second stroke being a test stroke or a non-text stroke; and labeling the gap as a change gap or a non-change gap based on the posterior probability.