GMIC package Gimp: effect “pattern lava” in a fire hydrant in Povoa do Varzim

G’MIC is a full-featured open-source framework for image processing for Gimp & Krita: http://gmic.eu/

GIMP is the GNU Image Manipulation Program: http://www.gimp.org/

Krita free software for drawing and painting: https://krita.org/

Póvoa de Varzim on wikipedia: https://en.wikipedia.org/wiki/P%C3%B3voa_de_Varzim