Short explanation
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Three color values for red, green, and blue are determined from the four CMYK values for cyan, magenta, yellow, and black, and converted to the following notation: rgb (red, green, blue).
When we convert the color red, it consists of 0% cyan, 100% magenta, 100% yellow, and 0% black. The CMYK notation is then as follows: cmyk (0%, 100%, 100%, 0%).
These color values are then converted to an RGB value. This gives the color value in RGB notation as rgb (255, 0, 0). There is always a loss of color accuracy to be expected when converting from CMYK to any other color format.
Calculation example
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We will describe a conversion from cmyk to rgb using the color alice blue as an example.
The starting value is the color in CMYK format:
CMYK = cmyk (6%, 3%, 0%, 0%)
These values are divided among the respective colors cyan, magenta, yellow, and black:
cyan = 6
Magenta = 3
yellow = 0
black = 0
These color values must now be converted from the CMYK color system to the decimal system of RGB. Since the colors do not match directly, the conversion is not so easy. The color values are determined with certain formulas.
Red = 255 * ((1 - Cyan / 100) * (1 - Black / 100))
Green = 255 * ((1 - Magenta / 100) * (1 - Black / 100))
Blue = 255 * ((1 - Yellow / 100) * (1 - Black / 100))
In our example, this means that at the beginning we have to calculate the value for red from cyan and black. Then we calculate the value for green from magenta and black. After that, we calculate the value for blue from yellow and black. This results in the following calculations:
red = 255 * ((1 - 6 / 100) * (1 - 0 / 100))
red = 240
green = 255 * ((1 - 3 / 100) * (1 - 0 / 100))
green = 247
blue = 255 * ((1 - 0 / 100) * (1 - 0 / 100))
blue = 255
To get the result of our calculation, we now need to convert the calculated decimal values to the RGB notation rgb (red, green, blue):
RGB = rgb (240, 247, 255)