As stated above:You are forgetting the light that is absorbed even by a white screen. Efficiency is the ratio of reflected light to incident light. So a 90% efficient reflective surface absorbs the 10% of the incident light.
And this is measured and noted as gain. Light reflected is measured as gain. There's no need to coin a new phrase for something that already exists.
I do not recall any RGB numbers for any of the white surfaces being 256 256 256. As a matter of fact, UPW which is considered to be one of the whiter paints, all be it with a slight blue push, has RGB numbers around 235 to 245 does it not. If we assume it is 240 then it is reflecting 240/256 or 93.75% efficient.
Would it really though? How much of that goes back at the viewer? The High Power does not appear to be anywhere near a 255 white nor near UPW. So if it falls around 220 would we say it is 86% efficient then?
If we are talking about a simple surface like paint then the less efficient it is the darker gray it looks right.
This depends upon your definition of efficient. What's being tossed around here talks about light but nothing with regards to the color of the light. So I wouldn't agree with that at all.
I think the pearl clear coats are introducing something that is not quite so linear. Like car window tinting. This even more evident on a black car with a nice clear coat or metallic gel coat. The car is no doubt black but the sun reflecting off of it sure does not look black. In many cases it is so bright you can't actually look at it. Yet when you hit the same car with a more diffuse or lower intensity light it looks black.
No I don't think it is magic but these sorts of interactions are currently unexplained in any scientific way, by us to us that is. In fact I still don't accept the notion that the simple polyurethane top coat is just adding some surface sheen. I don't deny that it may well be introducing surface sheen but that is not the significant contribution. I say this because the effect seems to be dependent on the underlying surface roughness. The poly works most effectively over a very rough flat finish like UPW #1050. I still believe the significant action is taking place at the poly paint interface. Similar to getting a colored stone wet. The color darkens and the variation in colors become more apparent.
How would you explain Fashion Grey then?
That reminds me, the fellow at the Behr Color Lab also indicated that there is more to it than that. I never did get his take on it. I should try to get him to comment on it.
Anyway while related to all this gain stuff surface wetting is even more of a stretch for people to grasp than increasing reflective efficiency.
It is an interesting discussion and I don't disagree with any of the basic concepts being put forward, I just think there may be more to it than we currently understand. Just like I know a one way mirror looks like a mirror on one side and like tinted glass on the other, but I don't really know why. Yes I know that the mirror side has to be brighter than the see through side and that if you swap which room is dark and which is light the one way direction will change but I don't know why.
Come up with a formula for that and then we can talk efficiency, otherwise you're sugar coating what's already there with a 'buzzword'.To me, three things can be used to describe a screen (of which I think the manufacturers only use two):
- Color Reproduction - see neutrality
- Viewing Angle/Cone
Now if someone were to come up with a wacky formula to add these three things up and spit out a value that can be compared to the user's environment and preference's... then we might be talking!
Maybe as we move along here we can come up with a formula that you can plunk all that data in, add some viewer expectations and get an 'efficiency' score. But in the past this term was tossed around a lot to avoid getting real measurements and because it sounded 'professional' to new folks. Now don't get me wrong, I have no problem with anyone using the word. I just think that it's being used incorrectly.