Optimization?

Let's recall the implementation of RasterUnionFind was based on Quick-Union. However, we did not incorporate any improvements (union-by-size or path compression). That said, it seems our implementation is performing path compression! For example, consider the output of ImageRegions for the color.png file:

Number of regions: 7
Region labels:

  0	  1	  1	  3	  3	

  1	  1	  1	  3	  3	

  1	  1	 12	 13	 13	

 15	 15	 13	 13	 13	

 15	 15	 13	 13	 24	

Notice, for instance, all the pixels in regions labeled with $1$ are directly connected to the root (the parentID for every pixel in that region is $1$). So is the case for other regions. You will find a similar pattern if you run the ImageRegions program for bw.png file. In the README.md file, elaborate if this is a lucky incidence or any aspect of our implementation increases the likelihood of this unplanned path compression. Keep the answer to a paragraph; be brief and to the point.