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6971af2416
* feat: code functional, commented, tested * fix: compering types, exception msg, line length * fix: type hints
72 lines
2.0 KiB
Python
72 lines
2.0 KiB
Python
def rgb_to_cmyk(r_input: int, g_input: int, b_input: int) -> tuple[int, int, int, int]:
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"""
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Simple RGB to CMYK conversion. Returns percentages of CMYK paint.
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https://www.programmingalgorithms.com/algorithm/rgb-to-cmyk/
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Note: this is a very popular algorithm that converts colors linearly and gives
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only approximate results. Actual preparation for printing requires advanced color
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conversion considering the color profiles and parameters of the target device.
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>>> rgb_to_cmyk(255, 200, "a")
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Traceback (most recent call last):
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...
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ValueError: Expected int, found (<class 'int'>, <class 'int'>, <class 'str'>)
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>>> rgb_to_cmyk(255, 255, 999)
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Traceback (most recent call last):
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...
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ValueError: Expected int of the range 0..255
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>>> rgb_to_cmyk(255, 255, 255) # white
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(0, 0, 0, 0)
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>>> rgb_to_cmyk(128, 128, 128) # gray
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(0, 0, 0, 50)
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>>> rgb_to_cmyk(0, 0, 0) # black
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(0, 0, 0, 100)
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>>> rgb_to_cmyk(255, 0, 0) # red
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(0, 100, 100, 0)
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>>> rgb_to_cmyk(0, 255, 0) # green
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(100, 0, 100, 0)
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>>> rgb_to_cmyk(0, 0, 255) # blue
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(100, 100, 0, 0)
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"""
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if (
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not isinstance(r_input, int)
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or not isinstance(g_input, int)
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or not isinstance(b_input, int)
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):
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msg = f"Expected int, found {type(r_input), type(g_input), type(b_input)}"
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raise ValueError(msg)
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if not 0 <= r_input < 256 or not 0 <= g_input < 256 or not 0 <= b_input < 256:
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raise ValueError("Expected int of the range 0..255")
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# changing range from 0..255 to 0..1
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r = r_input / 255
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g = g_input / 255
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b = b_input / 255
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k = 1 - max(r, g, b)
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if k == 1: # pure black
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return 0, 0, 0, 100
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c = round(100 * (1 - r - k) / (1 - k))
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m = round(100 * (1 - g - k) / (1 - k))
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y = round(100 * (1 - b - k) / (1 - k))
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k = round(100 * k)
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return c, m, y, k
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if __name__ == "__main__":
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from doctest import testmod
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testmod()
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