Actually I came upon this through MO a couple of days ago: in here (http://aimath.org/aimnews/lmfdb/) there is a mesmerizing image

The caption reads

A Maass form, one of the 20 different types of objects in the LMFDB.

Image by Fredrik Strömberg

Of course I could just email the person or Alina Bucur whose homepage hosts the image, or ask at LMFDB but I somehow prefer to start from here.

Does anyone know which Maass form is depicted here? What does the color coding mean? How has it been calculated? Where can I read about it?

After accepting an answer I found (in the "Related" column), in an answer to Zeroes of Maass forms a link to a more informative page by Strömberg with lots of different kind of images like

or

Then I also found another even more haunting and mysterious one at still different page, again without any details given. Let me reproduce this one too