[mwtidd]

We used a blue light, and an RGB threshold. With the exposure cranked way down on our axis camera, we had no issues detecting hot at week zero.

HSV is great for complex vision processing, but is really unnecessary if you are using the reflective tap and an LED ring light. I would expect that your G and B values would be very low.

For the blue light we had the following rgb values:

int redLow = 0;
int redHigh = 10;
int greenLow = 0;
int greenHigh = 10;
int blueLow = 50;
int blueHigh = 110;

We didn't need to do any calibrations at week zero.

You should be able to load your image into any photo editing tool and measure the rgb values. Gimp provides both RGB and HSV. I just find RGB more intuitive.