import numpy as np   # Standard numpy abbreviation : np
import mahotas as mh # Standard mahotas abbreviation : mh

#im = mh.imread('lena.jpg') # loads lena image
im = mh.demos.load('lena')

print im.shape
r,g,b = im.transpose((2,0,1)) # Obtain the red/green/blue/channels with numpy methods

imshow(im) # Display the image

# Let's play around with stretching the images:

print im ** 2.
imshow(im ** 2.)

# Matplotlib does not deal with that image very well
# mahotas.stretch to the rescue: stretches the image to be in 0..255 range:
imshow(mh.stretch(im ** 2.))

# We can manipulate each channel independently and then use mh.as_rgb to put them back together: 

imshow(mh.as_rgb(r**1.9, g, b**2))

imshow(mh.as_rgb(r**1.9, g**1.2, b**2))

im_filtered = mh.as_rgb(r**1.9, g**1.2, b**2)
mh.imsave('lena_filtered.jpg', im_filtered)