rgb_cmyk_conversion.py

defrgb_to_cmyk(r_input: int, g_input: int, b_input: int) ->tuple[int, int, int, int]:
"""
 Simple RGB to CMYK conversion. Returns percentages of CMYK paint.
 https://www.programmingalgorithms.com/algorithm/rgb-to-cmyk/

 Note: this is a very popular algorithm that converts colors linearly and gives
 only approximate results. Actual preparation for printing requires advanced color
 conversion considering the color profiles and parameters of the target device.

 >>> rgb_to_cmyk(255, 200, "a")
 Traceback (most recent call last):
 ...
 ValueError: Expected int, found (<class 'int'>, <class 'int'>, <class 'str'>)

 >>> rgb_to_cmyk(255, 255, 999)
 Traceback (most recent call last):
 ...
 ValueError: Expected int of the range 0..255

 >>> rgb_to_cmyk(255, 255, 255) # white
 (0, 0, 0, 0)

 >>> rgb_to_cmyk(128, 128, 128) # gray
 (0, 0, 0, 50)

 >>> rgb_to_cmyk(0, 0, 0) # black
 (0, 0, 0, 100)

 >>> rgb_to_cmyk(255, 0, 0) # red
 (0, 100, 100, 0)

 >>> rgb_to_cmyk(0, 255, 0) # green
 (100, 0, 100, 0)

 >>> rgb_to_cmyk(0, 0, 255) # blue
 (100, 100, 0, 0)
 """

if (
notisinstance(r_input, int)
ornotisinstance(g_input, int)
ornotisinstance(b_input, int)
 ):
msg=f"Expected int, found {type(r_input), type(g_input), type(b_input)}"
raiseValueError(msg)

ifnot0<=r_input<256ornot0<=g_input<256ornot0<=b_input<256:
raiseValueError("Expected int of the range 0..255")

# changing range from 0..255 to 0..1
r=r_input/255
g=g_input/255
b=b_input/255

k=1-max(r, g, b)

ifk==1: # pure black
return0, 0, 0, 100

c=round(100* (1-r-k) / (1-k))
m=round(100* (1-g-k) / (1-k))
y=round(100* (1-b-k) / (1-k))
k=round(100*k)

returnc, m, y, k


if__name__=="__main__":
fromdoctestimporttestmod

testmod()