In images consisting mainly of lines, it is the position and
orientation of the lines and their relationship to one another
that conveys information. Extra pixels are unwanted information that complicate the analysis, and removing them is
desirable [12]. To facilitate the extraction of image features, a thinning algorithm erodes, therefore reducing objects without changing their topology. For example, consider the bear images in Figure 2, both of them have the
shape of the same cute bear, but the image on the right has
the extra pixels removed and can now be further analysed
for shape.