Xyz is an additive color space based on how the eye intereprets stimulus from light. Unlike other additive rgb like Rgb, Xyz is a purely mathmatical space and the primary components are "imaginary", meaning you can't create the represented color in the physical by shining any sort of lights representing x, y, and z. It's complicated to explain in a nutshell, so read more about it here:
The Rgb color space consists of all possible colors that can be made by the combination of red, green, and blue light. It's a popular model in photography, television, and computer graphics.
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Color conversions performed using the open source ColorMine library.