1991-12-03 12:51:06 -04:00
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# Conversions between RGB and YIQ color spaces.
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1991-11-22 10:06:10 -04:00
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#
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1991-12-03 12:51:06 -04:00
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# R, G, B are amounts of Red, Green and Blue;
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# Y, I, Q are intensity (Y) and two difference signals (I, Q).
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# Convert a (R, G, B) triple to (Y, I, Q).
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# Scale is arbitrary (output uses the same scale as input).
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def rgb_to_yiq(r, g, b):
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y = 0.30*r + 0.59*g + 0.11*b
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i = 0.60*r - 0.28*g - 0.32*b
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q = 0.21*r - 0.52*g + 0.31*b
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return y, i, q
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# Convert a (Y, I, Q) triple to (R, G, B).
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# Input and output values are in the interval [0.0 ... 1.0].
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1991-11-22 10:06:10 -04:00
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1991-12-03 12:51:06 -04:00
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def yiq_to_rgb(y, i, q):
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r = y + 0.948262*i + 0.624013*q
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g = y - 0.276066*i - 0.639810*q
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b = y - 1.105450*i + 1.729860*q
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if r < 0.0: r = 0.0
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if g < 0.0: g = 0.0
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if b < 0.0: b = 0.0
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if r > 1.0: r = 1.0
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if g > 1.0: g = 1.0
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if b > 1.0: b = 1.0
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return r, g, b
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