PaletteOptimiser

optimiser.py

26:cd815af3effc
2015-10-01 Paul Boddie Reduced the frequency of the second colour in the dithering pattern. Added preview image generation support.
     1 #!/usr/bin/env python     2      3 from random import randint     4 from os.path import extsep, splitext     5 import EXIF     6 import PIL.Image     7 import math     8 import sys     9     10 corners = [    11     (0, 0, 0), (255, 0, 0), (0, 255, 0), (255, 255, 0),    12     (0, 0, 255), (255, 0, 255), (0, 255, 255), (255, 255, 255)    13     ]    14     15 def distance(rgb1, rgb2):    16     r1, g1, b1 = rgb1    17     r2, g2, b2 = rgb2    18     return math.sqrt(pow(r1 - r2, 2) + pow(g1 - g2, 2) + pow(b1 - b2, 2))    19     20 def brightness(rgb):    21     return distance(rgb, (0, 0, 0))    22     23 def factor(start, end, rgb):    24     r1, g1, b1 = start    25     r2, g2, b2 = end    26     gr, gg, gb = r2 - r1, g2 - g1, b2 - b1    27     r, g, b = rgb    28     pr, pg, pb = r - r1, g - g1, b - b1    29     dp = pr * gr + pg * gg + pb * gb    30     return dp / pow(distance(start, end), 2)    31     32 def darklight(rgb1, rgb2):    33     if brightness(rgb1) <= brightness(rgb2):    34         return rgb1, rgb2    35     else:    36         return rgb2, rgb1    37     38 def nearest(rgb, values=None):    39     l = map(lambda c: (distance(rgb, c), c), values or corners)    40     l.sort()    41     return l    42     43 def pattern(rgb, values=None):    44     l = nearest(rgb, values)    45     start, end = l[0][1], l[1][1]    46     f = factor(start, end, rgb)    47     #if f > 0.5:    48     #    start, end = end, start    49     #    f = 1 - f    50     return start, end, f    51     52 def choose(seq, f):    53     last = int(seq * f)    54     current = int((seq + 1) * f)    55     return last != current    56     57 def get_value(xy, rgb, width, height, values=None):    58     x, y = xy    59     rgb1, rgb2, f = pattern(rgb, values)    60     if choose(x + randint(0, width), f) and choose(y + randint(0, height), f):    61         return rgb2    62     else:    63         return rgb1    64     65 def get_best(rgb, values):    66     return nearest(rgb, values)[0][1]    67     68 def sign(x):    69     return x >= 0 and 1 or -1    70     71 def saturate_rgb(rgb, exp):    72     return tuple([saturate_value(x, exp) for x in rgb])    73     74 def saturate_value(x, exp):    75     return int(127.5 + sign(x - 127.5) * 127.5 * pow(abs(x - 127.5) / 127.5, exp))    76     77 def test():    78     size = 512    79     for r in (0, 63, 127, 191, 255):    80         im = PIL.Image.new("RGB", (size, size))    81         for g in range(0, size):    82             for b in range(0, size):    83                 value = get_value((g, b), (r, (g * 256) / size, (b * 256 / size)), size, size)    84                 im.putpixel((g, b), value)    85         im.save("rgb%d.png" % r)    86     87 def test_flat(rgb):    88     size = 64    89     im = PIL.Image.new("RGB", (size, size))    90     for y in range(0, size):    91         for x in range(0, size):    92             im.putpixel((x, y), get_value((x, y), rgb, size, size))    93     im.save("rgb%02d%02d%02d.png" % rgb)    94     95 def rotate_and_scale(im, width, height, rotate):    96     if rotate or x and x["Image Orientation"].values == [6L]:    97         im = im.rotate(270)    98     99     w, h = im.size   100     if w > h:   101         height = (width * h) / w   102     else:   103         width = (height * w) / h   104    105     return im.resize((width, height))   106    107 if __name__ == "__main__":   108     if "--test" in sys.argv:   109         test()   110         sys.exit(0)   111     elif "--test-flat" in sys.argv:   112         test_flat((120, 40, 60))   113         sys.exit(0)   114    115     width = 320   116     height = 256   117    118     input_filename, output_filename = sys.argv[1:3]   119     basename, ext = splitext(output_filename)   120     preview_filename = extsep.join([basename + "_preview", ext])   121    122     preview = "-p" in sys.argv[3:]   123     rotate = "-r" in sys.argv[3:]   124     saturate = sys.argv[3:].count("-s")   125     desaturate = sys.argv[3:].count("-d")   126    127     x = EXIF.process_file(open(input_filename))   128     im = PIL.Image.open(input_filename)   129     im = rotate_and_scale(im, width, height, rotate)   130    131     if preview:   132         im_preview = im.copy()   133    134     width, height = im.size   135    136     colours = []   137    138     for y in range(0, height):   139         c = {}   140         for x in range(0, width):   141             rgb = im.getpixel((x, y))   142    143             # Saturate if requested.   144    145             if saturate or desaturate:   146                 rgb = saturate_rgb(rgb, saturate and math.pow(0.5, saturate) or math.pow(2, desaturate))   147                 im.putpixel((x, y), rgb)   148    149             # Count the number of requested colours.   150    151             value = get_value((x, y), rgb, width, height)   152             if not c.has_key(value):   153                 c[value] = 1   154             else:   155                 c[value] += 1   156    157             if preview:   158                 im_preview.putpixel((x, y), value)   159    160         c = [(n, value) for value, n in c.items()]   161         c.sort(reverse=True)   162         colours.append(c)   163    164     if preview:   165         im_preview.save(preview_filename)   166    167     for y, c in enumerate(colours):   168         most = [value for n, value in c[:4]]   169         least = [value for n, value in c[4:]]   170    171         for x in range(0, width):   172             rgb = im.getpixel((x, y))   173    174             # Get the requested colours and choose the closest alternative for   175             # less common colours.   176    177             value = get_value((x, y), rgb, width, height)   178             if value in least:   179                 value = get_value((x, y), rgb, width, height, most)   180             im.putpixel((x, y), value)   181    182     im.save(output_filename)   183    184 # vim: tabstop=4 expandtab shiftwidth=4