Understanding Figure 3

[Davidyao99]

I am having a bit of difficulty understanding this figure and it will be helpful if someone could provide some insights. From my understanding, the third and fourth figure is the zoomed in version of the first and second figure for when the x-axis goes from 1-64 to 1-8. However, why do the values of the figure appear to be flipped? Shouldnt it remain as a lower left triangle?

Thanks for any help and great work!