Understanding the Hough transform: Hough cell support and its utilisation

The Standard Hough Transform (SHT) is used to find lines, circles and other image features in edge maps containing edge points. Edge points which potentially can 'vote' for a given line (called its 'line support') are highly dependent of line position and orientation due to the boundedness of images. If accumulator array peaks are used to find lines then peripherally located lines are missed. Uniform feature detection probability in all parts of the image requires normalisation of the accumulator array by the support. The paper describes some further applications of the concept of support when finding lines (e.g. determining dominant directions), and gives some guidelines on the choice of the coordinate system origin.