Measure Light Intensity in Lux or Lumen with IMAQ Light meter

[ericmateovisan]

Hi everyone!
I try to measure light intensity in Lux or Lumen in a machine vision project.
this is what I've done so far:

I grab the video from my webcam, and extract the Luminanc plane from the image and then wire it to IMAQ Light meter , which finally measure pixels Mean Intensity in the specified rectangle...

how can I convert this code to get me the Units Lumen or Lux ?

Thank you

Best Regards

Eric