src/gamma.py

   1 #!/usr/bin/python
   2
   3
   4 def gamma_table(table, gamma=0.45):
   5     for point in table:
   6         p1 = float(point) / spread
   7         p1 = p1 ** gamma
   8         out = int(p1 * spread) + start
   9         if out >= stop:
  10             out = stop - 1
  11         lut.append(out)
  12
  13     if start > 0:
  14         lut[0:0] = [lut[0]] * start
  15     if stop < 256:
  16         lut.extend([lut[-1]] * (256 - stop))
  17
  18     return lut
  19
  20
  21
  22 def input_table(start=0, stop=256):
  23     lut = [0] * start
  24     spread = stop - start
  25     lut.extend(range(spread))
  26     lut.extend([spread - 1] * (256 - stop))
  27     return lut
  28
  29 def cformat(table, name="SOME_TABLE", wrap=75):
  30     table = list(table)
  31     outs = ["static guint8 %s [%s] = {" % (name, len(table)),
  32             '    %s' % table[0]]
  33     for v in table[1:]:
  34         if len(outs[-1]) >= wrap:
  35             outs[-1] += ','
  36             outs.append('    %s' % v)
  37         else:
  38             outs[-1] += ', %s' % v
  39     outs.append('};\n')
  40
  41     print '\n'.join(outs)
  42
  43
  44 inputs_full = input_table()
  45 inputs_headroom = input_table(16, 236)
  46
  47 cformat(reversed(gamma_table(inputs_full)), "sparrow_rgb_gamma_full_range_REVERSE")
  48 cformat(reversed(gamma_table(inputs_headroom)), "sparrow_rgb_gamma_headroom_REVERSE")
  49
  50 cformat(reversed(gamma_table(inputs_full)), "sparrow_rgb_gamma_full_range_REVERSE")
  51 cformat(reversed(gamma_table(inputs_headroom)), "sparrow_rgb_gamma_headroom_REVERSE")
  52
  53