mirror of https://github.com/mamedev/mame.git
34 lines
704 B
Python
34 lines
704 B
Python
"""
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Assumes the input RGB image subpixels are all either 0 or 255.
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Counts the bright subpixels in the whole image. This should be divisible by 3.
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Creates a uniform alpha channel containing 255 minus 1/3 of
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the number of bright subpixels.
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Writes the RGBA image to the output file.
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"""
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import sys
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import numpy
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import PIL
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import PIL.Image
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if len(sys.argv) != 3:
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print("usage: add_alpha.py in.png out.png")
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sys.exit(1)
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img = PIL.Image.open(sys.argv[1])
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arr = numpy.asarray(img)
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count = (arr==255).sum()
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assert count%3 == 0
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count //= 3
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alpha = arr[:,:,0,None]*0 + (255-count)
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arr = numpy.concatenate((arr,alpha),axis=2)
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# DEBUG
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#print(arr)
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out = PIL.Image.fromarray(arr)
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out.save(sys.argv[2])
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