mandelbrot-cosine-numpy.py

#!/usr/bin/env python3
import numpy as np
from PIL import Image # Pillow fork of PIL

w, h = 1200, 960
xc, yc, scale = - 0.35, 0.005, 1.1
imax, zmax = 100, 100

x,y=np.ogrid[xc - scale: xc + scale: 1j * w,
    (yc - scale) * h/w: (yc + scale) * h/w: 1j * h]
c = x + 1j*y
ones = np.ones_like(x*y)
its = np.zeros_like(ones)
z = c * 0
np.warnings.filterwarnings('ignore', '(overflow|invalid)')

for n in range(imax):
    mask = abs(z.real) < zmax
    m = np.where(mask)
    its[m] = n
    z[m] = np.pi * np.cos(z[m])  + c[m]

backgnd = np.log(its - np.log(np.log(abs(z.imag))) / 3) / 3
np.putmask(backgnd, mask, 0*ones)
tones = np.array(3*[backgnd]).T
val = np.maximum(0.0, 1.0 - abs(1.0 - backgnd))
blues = np.array((val**4, val**2.5, val)).T
sepias = np.array((val, val**1.5, val**3)).T
color = np.where(tones<1.0, blues, sepias)
rgb = np.uint8(np.minimum(1.0, color) * 255)
img = Image.fromarray(rgb, mode="RGB")
img.save("mand.png")
img.show()