My implementation

.gitignore

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 *.i*86
 *.x86_64
 *.hex
+
+__targets

LICENSE

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 The MIT License (MIT)
 
+Copyright (c) 2017 Torbjörn Rathsman
 Copyright (c) 2015 Jon Ross
 
 Permission is hereby granted, free of charge, to any person obtaining a copy

README.md

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 # libcolor
-C color library
+
+This is a header-only C++ library for between different colorspaces. The type of a color value defines which colorspace the value lives in.
+
+## Implemented colorspaces
+
+The following colorspace conversions are implemented. In all cases the alpha value is untouched. Any hue component is returned in radians from 0 to 2π. Other values goes from zero to one.
+
+
+| From\To 	| HCYA 	| HCIA 	| HSLA 	| HSVA 	| RGBA 	| sRGBA 	| XYZA 	
+|---------	|------	|------	|------	|------	|------	|-------	|------	
+| HCYA   	|      	| No   	| No   	| No   	| Yes  	| No    	| No   	
+| HCIA    	| No   	|      	| No   	| No   	| Yes  	| No    	| No   	
+| HSLA    	| No   	| No   	|      	| No   	| No   	| Yes   	| No   	
+| HSVA    	| No   	| No   	| No   	|      	| No   	| Yes   	| No   	
+| RGBA    	| Yes  	| Yes  	| No   	| No   	|      	| Yes   	| Yes  	
+| sRGBA   	| No  	| No   	| Yes  	| Yes  	| Yes  	|       	| No   	
+| XYZA    	| No   	| No   	| No   	| No   	| Yes  	| No    	|      	
+
+To convert from XYZA to HSVA you would do the following:
+
+    using namespace Color;
+    auto hsva=static_cast<HSVA>( static_cast<SRGBA>( static_cast<RGBA>(color_in)));
+
+The reason for this three-step conversion is to avoid possible ambiguities and errors.
+
+### HCY'A (Hue Chroma Luma Alpha)
+This is a perceptual colorspace. The hue is defined identically to HSL and HSV, but the lightness uses the ITU-709 luma weights
+
+### HCIA (Hue Chroma Intensity Alpha)
+This colorspace uses the same formulae for hue and chroma as HCY'A, but uses linear input instead of sRGB values. The intensity is the average of all color channels.
+
+### HSLA (Hue Saturation Lightness Alpha)
+This is the colorspace used in Windows color picker dialog.
+
+### HSVA (Hue Saturation Value Alpha)
+This is the colorspace used in the GTK+ color picker dialog. 
+
+### RGBA (Red Green Blue Alpha)
+This is the linear RGB space.
+
+### sRGBA (standard Red Green Blue Alpha)
+This is the RGB space used for most images on the Internet.
+
+### XYZA (CIE)
+This colorspace is sometimes used as an intermediate step between reallity and RGB
+
+### Y'CbCr (Luma Chroma_b Chroma_r)
+This colorspace is used with photographic compression and video. This implementation uses the ITU-709 weights.