Faster Mandelbrot image generation using numpy in Python

#
# fractal.py - Mandelbrot image generation using numpy
# Written by Ted Burke - last updated 2-11-2014
#

import numpy

# Define image size and region of the complex plane
w,h = 1280,1280
remin,remax = -2.0, 2.0
immin,immax = -2.0, 2.0

# Create numpy arrays for pixels and complex values
p = numpy.zeros((h, w), dtype=numpy.uint8)
z = numpy.zeros((h, w), dtype=complex)
c = numpy.linspace(remin,remax,w) * numpy.ones((h,w)) + \
    1j * numpy.linspace(immax,immin,h).reshape(h,1) * numpy.ones((h,w))

# Iterative pixel calculation
for n in range(255):
    z = z*z + c
    p = p + (abs(z) < 2.0)

# Output image to binary PGM file
f = open('fractal.pgm', 'wb')
f.write('P5\n{0} {1}\n255\n'.format(w, h))
f.write(p)
f.close()

I ran the program and converted the image to PNG format using ImageMagick as follows:

python fractal.py
convert fractal.pgm fractal.png

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