src/filters.py

   1 """Image filters module.
   2
   3 All filters return a filtered copy of the image, the original image is
   4 preserved.
   5 """
   6
   7 from PIL import Image, ImageFilter
   8
   9 import pcf
  10
  11 def color_enhance(image):
  12     """Stretch all color channels to their full range."""
  13     image_l = image.load()
  14     min_r, min_g, min_b = 999, 999, 999
  15     max_r, max_g, max_b = -1, -1, -1
  16
  17     for x in xrange(image.size[0]):
  18         for y in xrange(image.size[1]):
  19             min_r = min(min_r, image_l[x, y][0])
  20             max_r = max(max_r, image_l[x, y][0])
  21             min_g = min(min_g, image_l[x, y][1])
  22             max_g = max(max_g, image_l[x, y][1])
  23             min_b = min(min_b, image_l[x, y][2])
  24             max_b = max(max_b, image_l[x, y][2])
  25
  26     new_image = Image.new('RGB', image.size)
  27     new_image_l = new_image.load()
  28     for x in xrange(image.size[0]):
  29         for y in xrange(image.size[1]):
  30             r, g, b = image_l[x, y]
  31             r = (r - min_r) * 255 / (max_r - min_r)
  32             g = (g - min_g) * 255 / (max_g - min_g)
  33             b = (b - min_b) * 255 / (max_b - min_b)
  34             new_image_l[x, y] = (r, g, b)
  35
  36     return new_image
  37
  38 def edge_detection(image):
  39     """Edge detection (on BW images)."""
  40     new_image = image.filter(ImageFilter.GaussianBlur())
  41     # GaussianBlur is undocumented class, it might not work in future versions
  42     # of PIL
  43     new_image = Image.fromstring('L', image.size,
  44                              pcf.edge(image.size, image.tostring()))
  45     return new_image
  46
  47 def peaks(image):
  48     """Peak filter (on BW images)."""
  49     image_l = image.load()
  50     new_image = Image.new('L', image.size)
  51     new_image_l = new_image.load()
  52
  53     for x in range(2, image.size[0] - 2):
  54         for y in range(2, image.size[1] - 2):
  55             pix = (sum([sum([
  56                 - image_l[a, b]
  57                     for b in range(y - 2, y + 3)])
  58                     for a in range(x - 2, x + 3)])
  59                 + (17 * image_l[x, y]))
  60             if pix > 255:
  61                 pix = 255
  62             if pix < 0:
  63                 pix = 0
  64             new_image_l[x, y] = pix
  65     return new_image
  66
  67 def high_pass(image, height):
  68     """High pass filter (on BW images)."""
  69     image_l = image.load()
  70     new_image = Image.new('L', image.size)
  71     new_image_l = new_image.load()
  72
  73     for x in xrange(image.size[0]):
  74         for y in xrange(image.size[1]):
  75             if image_l[x, y] < height:
  76                 new_image_l[x, y] = 0
  77             else:
  78                 new_image_l[x, y] = image_l[x, y]
  79
  80     return new_image
  81
  82 def components(image, diameter):
  83     # TODO comment
  84     # TODO refactor
  85     image_l = image.load()
  86     new_image = Image.new('L', image.size)
  87     new_image_l = new_image.load()
  88
  89     components = [None]
  90     comp_counter = 1
  91
  92     if diameter == 1:
  93         for y in xrange(1, image.size[1] - 1):
  94             for x in xrange(1, image.size[0] - 1):
  95                 if image_l[x, y]:
  96                     s = {0}
  97                     s.add(new_image_l[x - 1, y - 1])
  98                     s.add(new_image_l[x, y - 1])
  99                     s.add(new_image_l[x + 1, y - 1])
 100                     s.add(new_image_l[x - 1, y])
 101                     if len(s) == 1:
 102                         components.append(set())
 103                         new_image_l[x, y] = comp_counter
 104                         components[comp_counter].add((x, y))
 105                         comp_counter += 1
 106                     elif len(s) == 2:
 107                         s.remove(0)
 108                         c = s.pop()
 109                         new_image_l[x, y] = c
 110                         components[c].add((x,y))
 111                     else:
 112                         s.remove(0)
 113                         c1, c2 = s.pop(), s.pop()
 114                         components[c2].add((x, y))
 115                         for (x1, y1) in components[c2]:
 116                             new_image_l[x1, y1] = c1
 117                         components[c1] = components[c1] | components[c2]
 118                         components[c2] = None
 119     elif diameter == 2:
 120         for y in xrange(2, image.size[1] - 2):
 121             for x in xrange(2, image.size[0] - 2):
 122                 if image_l[x, y]:
 123
 124                     s = {0}
 125                     for (a, b) in [(a,b) for a in range(x - 2, x + 3)
 126                               for b in range(y - 2, y + 1)]:
 127                         if not (b == y and a >= x):
 128                             s.add(new_image_l[a, b])
 129
 130                     if len(s) == 1:
 131                         components.append(set())
 132                         new_image_l[x, y] = comp_counter
 133                         components[comp_counter].add((x, y))
 134                         comp_counter += 1
 135                     elif len(s) == 2:
 136                         s.remove(0)
 137                         c = s.pop()
 138                         new_image_l[x, y] = c
 139                         components[c].add((x,y))
 140                     else:
 141                         s.remove(0)
 142                         c1 = s.pop()
 143                         components[c1].add((x, y))
 144                         new_image_l[x, y] = c1
 145                         for c2 in s:
 146                             for (x1, y1) in components[c2]:
 147                                 new_image_l[x1, y1] = c1
 148                             components[c1] = components[c1] | components[c2]
 149                             components[c2] = None
 150     else:
 151         pass #TODO error
 152
 153
 154     new_image = Image.new('L', image.size)
 155     new_image_l = new_image.load()
 156
 157     for component in components:
 158         if component:
 159             x_c = 0
 160             y_c = 0
 161             c = 0
 162             for (x, y) in component:
 163                 x_c += x
 164                 y_c += y
 165                 c += 1
 166             new_image_l[int(round(float(x_c)/c)), int(round(float(y_c)/c))] = 255
 167
 168     return new_image
 169