Color verification of LED's, How to determine the correct standard illuminant

[jack@nz]

Hi guys, this is the scenario:

I need to determine LED colors with ( machine vision + LABVIEW).

LABVIEW allows me to sample the RGB value of a  picture and convert it into a point on the CIE xyY color space.

To get from here to the color of the LED, the method I have in mind is to calculate the gradient between the point obtained and the white point.

The question:

I am not sure which how to select the white point?   The standard white points that I can find on the internet are for objects reflecting the illuminant.

Where as in my case, the object of interest (the LED) emits light itself. I wonder how would this affect the selection of white point.

On the otherhand, I wonder if ambient lighting would affect the hue of the LED color sampled?

It would be greatly appreciated if anyone can help me  

[muks]

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I am not sure which how to select the white point?   The standard white points that I can find on the internet are for objects reflecting the illuminant.

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Can u explain it in a better  way.I am not getting your point

[muks]

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On the otherhand, I wonder if ambient lighting would affect the hue of the LED color sampled?

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Yup it will affect the  not only hue but  luminance as well.Give a description of your setup and  the camera u r using or planning to use.