ThickLine Creation in Matlab

I was attempting to create a thick line from paper-based sketches by using Matlab. I want to get an idea, what operation can be used in Matlab to achieve this. I have some resources but still confuse. This is a solution I found from journal article:

Starting from the top-left corner of the overtraced sketch image, a square window with its size about the largest pixel gap between the overtraced lines in the sketch is slid 1 pixel at a time along the image from left to right and from top to bottom. At each position, the number of data points inside the window (nw) is determined and compared with an assigned threshold value (T) which is the window width. Unless the number of the data points is less than the threshold value, the center point of the window is recorded as their representative on a new image. By allowing overlapping between the windows, these center points will form the thick-line sketch.

Based on the given sentences, what type operation can be applied in Matlab?Im desperately need help on this. If anyone can assist me on algorithm is highly appreciated.

Tq in advance