In this section, we are going to discuss some variants of the traditional LBP operator that we have been discussing so far. We are going to look at the variants with respect to:
How the neighboring points are sampled.
How the binary codes (and equivalently, the corresponding decimal numbers) are used to construct the histogram.
Let's look at some variations with respect to criterion 1. The LBP codes that we have described in the previous sections used a 3 x 3 local neighborhood and compared it with eight neighbors. All the neighbors were at a distance of 1 pixel from the central pixel. This situation is described in the leftmost figure in the following diagram. In terms of notation, this is described as . The 8 here stands for the number of neighbors, whereas the 1 refers to the distance of each neighbor from the central pixel.
We can take larger neighborhoods and compare them with more than eight neighbors. Such a situation is shown in the figure in the middle. Note that we...