Color conversion between color spaces

I'm creating a library that allows conversion between the following color spaces:

HSV, HLS, RGB, CMYK, HEX

Up until now, I have the following conversions implemented:

HSV -> HLS

HSV -> RGB

HSV -> CMYK (HSV -> RGB -> CMYK :: see NB)

RGB -> HSV

RGB -> HLS

RGB -> CMYK

RGB -> HEX

HLS -> RGB

HLS -> HSV

HLS -> CMYK (HLS -> RGB -> CMYK :: see NB)

CMYK -> RGB

CMYK -> HSV (CMYK -> RGB -> HSV :: see NB)

CMYK -> HLS (CMYK -> RGB -> HLS :: see NB)

NB: HSV and HSL can't be directly converted to CMYK because they're not absolute color spaces. They need elements of the RGB space so that the conversion to CMYK is meaningful. (CMYK color to HSV color directly)

Right now, I have to implement all the HEX conversions:

HEX <-> R开发者_开发技巧GB

HEX <-> HSV

HEX <-> HLS

HEX <-> CMYK

Converting between HEX and RGB is simple and I have it implemented. What bothers me are the HEX <-> HSV and HEX <-> HLS conversions. Is there a direct way to convert HEX to HSV and HSL or do I have to use HEX -> RGB -> HSV/HLS? What about HEX <-> CMYK?

Any help would be greatly appreciated.

Typically the HEX values are just HEX representations of each individual channel's values concatenated together. If all of your colors are represented by 8 bits and you are looking for a HEX representation that can be used in HTML it would be like this:

Color  8 bit            HEX value
---------------------------------
RGB    255,128,0        FF8000
CMYK   255,128,255,128  FF80FF80