57 строки
1.4 KiB
Python
57 строки
1.4 KiB
Python
#!/usr/bin/env python
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# $URL: http://pypng.googlecode.com/svn/trunk/code/pipcolours $
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# $Rev: 96 $
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# pipcolours - extract all colours present in source image.
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def colours(out, inp):
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import itertools
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import png
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r = png.Reader(file=inp)
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_,_,pixels,info = r.asDirect()
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planes = info['planes']
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col = set()
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for row in pixels:
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# Ewgh, side effects on col
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map(col.add, png.group(row, planes))
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col,planes = channel_reduce(col, planes)
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col = list(col)
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col.sort()
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col = list(itertools.chain(*col))
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width = len(col)//planes
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greyscale = planes in (1,2)
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alpha = planes in (2,4)
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bitdepth = info['bitdepth']
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w = png.Writer(width, 1,
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bitdepth=bitdepth, greyscale=greyscale, alpha=alpha)
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w.write(out, [col])
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def channel_reduce(col, planes):
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"""Attempt to reduce the number of channels in the set of
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colours."""
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if planes >= 3:
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def isgrey(c):
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return c[0] == c[1] == c[2]
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if min(map(isgrey, col)) == True:
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# Every colour is grey.
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col = set(map(lambda x: x[0::3], col))
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planes -= 2
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return col,planes
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def main(argv=None):
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import sys
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if argv is None:
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argv = sys.argv
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argv = argv[1:]
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if len(argv) > 0:
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f = open(argv[0], 'rb')
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else:
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f = sys.stdin
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return colours(sys.stdout, f)
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if __name__ == '__main__':
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main()
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