This is a 5 shot bracketed exposure fused together with Enfuse. A Free Open Source software package for creating natural looking HDR (High Dynamic Range) images. Besides exposure blending Enfuse can do Focus stacks and more, but that’s for another day.
Available for Linux, Mac and Windows as a command line program, vary capable but not much fun to work with. Search Google for EnfuseGUI, an Open Source graphical user interface for Mac & Windows written by Ingemar Bergmark.