GNU nano 2.0.9                 File: edgefinder.py
import Image
import ImageFilter

def edgemap(path):
  thresh=60
  im = Image.open(path).convert("L")
  width=im.size[0]
  length=im.size[1]
  #im.show()
  im=im.filter(ImageFilter.BLUR)
  #im.show()
  im=im.filter(ImageFilter.SHARPEN)
  #im.show()
  raw_data=list(im.getdata())
  hist_16bin=[0]*16
  for i in range(len(raw_data)):
      hist_16bin[raw_data[i]/16]=hist_16bin[raw_data[i]/16]+1
  #print raw_data
  print hist_16bin
  x_mask=[[-1, 0, 1], [-2, 0, 2], [-1, 0, 1]]
  y_mask=[[1, 2, 1], [0, 0, 0], [-1, -2, -1]]
  edge_data=[0]*len(raw_data)

  for i in range(len(raw_data)):
    if (not(i<width or i>(width*length)-width or i%width==0 or (i+1)%width==0)):
      kernel=[[raw_data[i-(width+1)], raw_data[i-width], raw_data[i-(width+1)]],
              [raw_data[i-1], raw_data[i], raw_data[i+1]],
              [raw_data[i+(width-1)], raw_data[i+width], raw_data[i+(width+1)]]]
      grad_x=gradient(kernel, x_mask)
      grad_y=gradient(kernel, y_mask)
      grad=abs(grad_x)+abs(grad_y)
      if (grad>thresh):
        edge_data[i]=255
  edge_str="".join(chr(x) for x in edge_data)
  edge_img=Image.frombuffer("L", im.size, edge_str, "raw", "L", 0, 1)
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