Fractal Perlin Noise

Sum over mutliple instance with increasing frequencies
pictures/perlin.png
pictures/perlin_2d_00.png pictures/perlin_2d_01.png pictures/perlin_2d_02.png pictures/perlin_2d_03.png pictures/perlin_2d_04.png
\(\;\;\;\;\;\;\;f(x)\)
\(0.8\,\,\,f(2\,x)\)
\(0.8^2\,f(4\,x)\)
\(0.8^3\,f(8\,x)\)
\(0.8^4\,f(16\,x)\)