white balance - How to estimate colour temperature of the illuminant from a photograph of a standard colour chart?

I am working on a digital still camera. I need to compute the colour temperature of the illuminant programmatically using some algorithm (not using a third party tool from Adobe or etc.).

In my case images are captured using my experimental/under development camera, and the illuminant is not a standard illuminant with a known colour temperature. I need this for colour correction/white balancing. I am looking to estimate Colour Temperature (degree Kelvin) of a light-source illuminant based on some statistics of the RGB data or the Raw Bayer data of the captured image of say a standard colour chart (24 colour patches) under this illuminant.

How can I estimate the colour temperature from this colour chart data?

Any pointers or reading material or algorithm which talks about it would help.