# Load neccessary python modules
from skimage import io, color, filter,transform # skimage is an image processing library
import matplotlib.pyplot as plt # matplotlib provides plot functions similar to MATLAB
import numpy as np # numpy provides efficient matrix implementation in python
from scipy import signal # scipy provides scientific computing functions
from IPython.html.widgets.interaction import interact 
# interact function can create an interactive interface to allow user to manipulate parameters and see the result, 
# similar to "Manipulate" in Mathematica

%matplotlib inline 
# configuration of matplotlib


# Load a natural image
im = io.imread('pic/Zebra_running_Ngorongoro.jpg');
zebraIm = color.rgb2grey(im)
# Show image
plt.figure(); io.imshow(zebraIm)

def SquareKernel(r):
    w = 2*r + 1
    return np.ones((w,w)) / (w**2)

im = zebraIm
def AdjustKernelRadius(r):
    fim = signal.convolve2d(im, SquareKernel(r))
    io.imshow(fim)
interact(AdjustKernelRadius, r=(1,10))


filter1 = np.array([[1,1,1], [1,-8,1], [1,1,1]])
plt.figure(); io.imshow(signal.convolve2d(zebraIm, filter1))

fVertical = np.array([[-1,-1,-1], [2,2,2], [-1,-1,-1]])
fHorizontal = np.array([[-1,2,-1], [-1,2,-1], [-1,2,-1]])
plt.figure(); io.imshow(signal.convolve2d(zebraIm, fVertical))
plt.figure(); io.imshow(signal.convolve2d(zebraIm, fHorizontal))

type(zebraIm)