Fast decomposition of digital curves into polygons using the Haar transform
Timothy J. Davis · IEEE Transactions on Pattern Analysis and Machine Intelligence · 1999
The perimeters of features in digital images are decomposed into sets of straight lines using the Haar transform. The Haar basis functions preserve sharp changes in direction along the perimeter while still allowing smoothing. The coefficients of the Haar transform are simply related to the error between the polygonal decomposition and the true perimeter. The Haar transform can be calculated efficiently with a computational overhead linear in the number of data points.