Figure 6

Gradient Path Labelling Algorithm. A step-by-step diagram of the gradient path labelling procedure is presented in this figure. The procedure receives the input image and analyses every pixel in a top-left, bottom-right direction. For every pixel it applies a labelling procedure, by propagating labels throughout its gradient direction and by detecting equivalent labels. At the end of the pixel analysis, label equivalences are applied in order to produce an image where each maximum is represented by a unique label. Finally, to reduce the over-segmentation produced by the algorithm, a label merging algorithm is applied. This merging algorithm groups adjacent regions that met the predefined amplitude merging conditions.