Roy,
There are two concepts of intensity; one is independent of US, independent of our ability to SEE the light with our very own eyes. That is the sense in which intenisity is being used here (we are, after all, talking physics here). You're talking PSYCHOPHYSICS. PSYCHOPHYSICS is different, Roy. This thread is not about General Relativity in Psychophysics. It's about General Relativity.
Light intensity - WikipediaPsychophysics - Wikipedia
With that said, Ned got this wrong:
The intensity of light is a measure of the number of photons arriving in unit time.
The intensity of light is a measure of the the number AND ENERGY of photons arriving in unit time. At least, as far as I can tell.
Anyway, let's drop it. The original question still stands; all these mistakes and corrections simply obscure it. Let's talk some real physics!