Zoomed in on the bottom right corner to show more detail. Again here is the raw image that the map is upscaled from:
A single pixel in the original map becomes 16*16 pixels in the new map, but it can get arbitrarily zoomed in. I tried two different approaches before settling on this one. This technique converts the pixel map into a curve. I realised that it would be nice to have this information anyway, so I figure I might as well use it.