Aquatint Image Processor
This web app applies an aquatint texture effect to an uploaded image using a method developed by Prof Yannick Meurice and inspired by the Ising model, a simplified model for ferromagnetism. The method is described in "Making digital aquatint with the Ising model" published in the American Journal of Physics. Additional information can be found in the writings of Alan McKay.
The web app transforms an image of your choice with not too many pixels (less than 3MB). First, the pixels are separated into pure black and white regions at a fractional "greycut" that you can adjust in order to emphasize features you like. The pixels with a grey value above the grey cut become black while the others stay white. This represents an initial localized ferromagnetic field with either up or down spins which can be visualized as small magnets. Physical systems have a Boltzmann probability distribution controlled by temperature, with higher temperature yielding greater disorder. The program picks a typical spin configuration for a chosen temperature with a method called "importance sampling". Temperatures below 2.27 correspond to the ordered "spontaneous magnetization" phase. The final adjustable parameter, "sweeps", controls the number of iterations of importance sampling applied. Enjoy trying different choices!