Grouping lines in freeform handwritten text

Abstract

Techniques for efficiently and accurately organizing freeform handwriting into lines. A global cost function is employed to find the simplest partitioning of electronic ink strokes into line groups that also maximize the 'goodness' of the resulting lines and the consistency of their configuration. The 'goodness' of a line may be based upon its linear regression error and the horizontal and vertical compactness of the strokes making up the line. The line consistency configuration for a grouping of strokes is measured by the angle difference between neighboring groups. The global cost function also takes into account the complexity of the stroke partitioning, measured by the number of lines into which the strokes are grouped. An initial grouping of strokes is made, and the cost for this initial grouping is determined. Alternate groupings of the initial stroke grouping are then generated. The global cost of each of these alternate stroke groupings is then calculated, and the stroke grouping that produces the largest global cost decrease from the global cost of the original grouping is selected. The alternate grouping creation, cost determination and evaluation, and grouping selection process then is repeated until the global cost for new grouping alternates no longer decreases.