Generate tile-able (in 1 direction) mountains. Useful for game backgrounds.

fractal_mountains.py

import random
import Image

def fractal_mountain(pixels, damping, seed=0.0):
    px = [seed, seed]
    factor = 1.0;
    while(len(px) < pixels):
        # loop through and generate
        new_p = []
        for i in range(1, len(px)):
            r = 2*random.random() - 1;
            new_p = new_p + [min(abs((px[i] + px[i-1])/2.0 + r*factor),1.0)]

        factor = factor * damping
        px_new = []
        for i in range(len(px)-1):
            px_new = px_new + [px[i]] + [new_p[i]]
        px_new = px_new + [px[-1]]
        px = px_new
    return px


def generate_mountain(sz, damping, seed):
    im = Image.new("RGBA", sz, (0, 0, 0, 0))
    px = im.load()

    d = fractal_mountain(sz[0], damping, seed)
    d = d[:sz[0]]

    for i in range(sz[0]):
        r = d[i]*sz[1]
        for j in range(int(r)):
            px[i,(sz[1] - 1) - j] = (0,0,0,255)

    return im


if __name__ == "__main__":
    random.seed()
    
    for i in range(3):
        for j in range(2):
            im = generate_mountain((512,256), 0.5 - 0.05*i, 0.4)
            im.save("./output_" + str(i) + "_" + str(j) + ".png")