Using Gimp filters on a smoke pattern

The following Gimp features and filters were used to alter the smoke pattern:
Gaussian blur, dodge duplicate layer, invert, desaturate, despeckle, treshold, merge layer down. Various Gimp tutorials entitled this affect "perfect masking using a highpass."
See, for example, http://www.tutorialized.com/view/tutorial/Perfect-masking-using-a-highpass/28768 and http://www.gimp.org/tutorials/Sketch_Effect/