measure the illumination

is there a way to measure the illumination of pixels seeing the pixel information?

http://i53.tinypic.com/9r698o.png this image information is from a gray scale picture

units as LUMEN or LUX?

Thanks in advance

Answer 1

[David Young]

No, the camera would need to be calibrated if you want absolute values of the illumination. Even relative values depend on the camera's response curve.