This is going to be long, just a warning.
There always seems to be an ongoing debate about gray. Either about its ambient properties, or that it takes more than gray to make an ambient light screen, or it kills whites and makes images look muddy to it is the best type of screen a person could have. So who's right and who's wrong? Everybody and nobody.
A lot depends on a person's personal tastes and what they like. Gray undeniably helps with black levels and contrast for projectors with less than stellar contrast ratios. It is also better with lighting in a room and can deal with ambient light better than a white screen can. I still do not feel this makes it a true ambient light screen, but as stated by others I agree it is better than a white screen and more appropriately should be called ambient light friendly.
The debate about grays is still roaring on. I find it interesting that for the most part everyone is saying the same thing but arguing different points. To me the debate breaks down to not whether gray is good or bad, but what gray should be used. Some have even said that grays are a passing thing and back in 2003 it was said by one person that
Grey screens as you may recall were introduced at least in a large part, to enhance the sorry CR most digital projectors suffer from. That's changing. The low CR high lumen projectors of yesterday are giving way to designs much more suited for home theater.
I feel a member of your talents is spending a great deal of time and effort on something that will be behind us in a year or two. Let's face it, no one would had ever given grey so much a thought if the blacks looked right on white screens. Ever been to a film cinema where they project on a grey screen?
What I'm saying in a nutshell: grey is a dying horse. I would enjoy seeing your talents focus elsewhere. Even I, one time defender of the grey, ME in particular, see the handwriting on the wall. Thanks for listening.
(This was not a quote towards me since my talents are limited)
Hence the saying Never say never', and dealing with absolutes is always a touchy area as well. It is now the end of 2006; three years after that statement and grays are still very much in demand. Commercial screen companies have not dropped them; in fact they have increased the number of gray screens as well as enhanced their performance. The big question though is WHICH gray?
I find it interesting that neutral gray is viewed by some as the Holy Grail of gray screens. This has been debated for a long time now. Some have gone back and forth in this debate, stating neutral is the way to go and then later questioning why the importance of a neutral. I have questioned this myself since manufactured screens are not completely neutral. If you look at the color curve once the spectrophotometer values are converted to RGB, most have a distinctive V' curve. So the question is why would they do this? Here are some explanations I got: (And thank you Prof for providing this explanation)
1. They did it on purpose- so the screen will look good even if the projector is off a little. A red or blue push doesn't look too bad, but a green push kills skin tone- and this is how many people judge image quality.
2. They did it accidentally- when gray came into popularity, they just used the most common standard, which is illuminant C (6774K). Many commercial grays are almost exactly on for illuminant C, but there are some that are not
3. They did it cause their cheap- Variation is much less important this way and pigments aren't as critical.
So I asked the question if commercial screen companies aren't concerned about their gray's being neutral, should we? That's like the opening statement about who's right and who's wrong yes we should be concerned, yet no we shouldn't but both of those answers have a reason in my opinion.
If we look at what I call the V' curve for most commercial screens, we see they are green deficient, but usually the red and blue components are relatively balanced. There are instances where there is a slight blue push, or a slight red one, (or a slight deficiency). A slight' push in either of these colors can actually be beneficial in some instances. A slight red deficiency could help some with incandescent lighting since it leans in that direction, while a slight blue push can make whites appear whiter' (another color conditioning we all have had since we were born). The trick and key is knowing when the push is too much.
A few years ago DIY was dealing with these questions and ideas, but for the most part there was no data. The spectrophotometer tests that have been done recently, as well as the converting of that data to RGB values has done a lot in the way of understanding commercial screens as well as now knowing the color composition of DIY methods. RGB is widely debated by some as being useless when discussing screens. I disagree. It's hard for the average person to understand CIE data and looking at those numbers isn't easy for someone not used to what they mean to determine if a color is pushing to hard one way or another. RGB makes it easy to quickly see the color curve. If the V' is in line with typical commercial screens, then yes that color would most likely make a nice screen- as long as the color itself isn't some wild off the wall color. If it is a white or gray then I would have no problem using it as a screen.
So I just completely contradicted myself when it comes to neutral grays? Not really. Even though it was just stated and shown that commercial screens tend to have a slight green deficiency, that doesn't mean a neutral color is bad just that the commercial companies strive for the best image across the widest range of projectors AND consumers tastes. As stated earlier, green can push hard even with the slightest increase in RGB value. Most people only do basic calibrations. This way the commercial screen looks good out of the box to most users and projectors.
Seeing color is a sensation, like hearing, taste, or smell. Sensations are not felt the same way by every person. Food tastes differently to each person. In the same way, there is no absolute color that is inherently seen the same way by every person. Nor is every person's vision the same. This is where neutrals come into play.
Neutral gray will eliminate/reduce color contamination from reflected light. Even though slight variances in screen composition and colors will work fine, a neutral palate is the best at reflecting the colors back the most accurately.
Also different light sources affect the colors that you see. For instance, a color viewed under fluorescent light will look radically different when viewed under incandescent light. Fluorescent light adds green to colors while incandescent light adds red. (This is why a slight red deficiency in screen color can be helpful with incandescent lighting)
A front projection Home Theater system consists of several devices that all deal with color at some level, and in different ways. Projectors deal with colors being created by light, and the screen deals with colors being reflected by pigments. Because all of these components in the system handle color in different ways, color reproduction between them is not so obvious. They use different color models, have different color gamuts and different Gammas. Moreover their colors are influenced by calibration settings and environment. Again neutral colored screens reflect the light from the projector with the least amount of color skewing.
What really sold me was when I went from a bright white screen like Designer White to the SW 7071 Gray Screen. I haven't done a full blown calibration yet, but in the quick setup I did I found that the more neutral the gray, the less color adjustment is needed. In my case and with my quick setup I did not touch the color settings at all between the two screen colors, only the brightness and contrast levels. I do feel the picture will be even better after a full calibration, but my point is with other grays I DID have to make some drastic adjustments to the color.
I am not abandoning any previous research and testing I have done. I think both can coexist as long as the V' curve isn't radically pushed by the red or blue components it will work just fine. Neutral grays however will allow us to go darker with fewer color problems than if the gray is not neutral and meant to be an aesthetically pleasing color as a wall paint.
Many people have been searching for neutral grays for a long time now. It's not that they didn't know what they were looking for; it has more to do with technology and more readily available data. Now we can actually see spectro data and the RGB breakdown of colors where a couple of years ago that type of data didn't exist in here, at least not from what I have seen. Now that we found neutral grays, it's kind of ironic that the discussion is pulling away from them and suggesting non-neutrals. Both will definitely work, and like I said earlier, everyone's tastes are different. I think one benefit of a neutral gray besides allowing us to explore darker shades, is that since the color skew is at its minimum; once the screen is calibrated it stands a better chance of being pleasing to a wider group of people. I know when I finally found a compromise' with one gray paint I used, it still wasn't optimal. Even though I probably could have gotten used to the color shift, anyone else walking in for the first time would most likely see it was off since they were not adjusted' to the screen themselves. To me that is a bad screen. People should not be told Well you'll get used to it' there should be no reason to.
I'd like to think what I just wrote will not be taken as anything personal by anyone since it was not meant that way. I have done a lot of research recently into colors and specifically grays. These are my findings and how I feel about gray for projector screens I am by no means saying this thread is the definitive thread about neutral grays, or that everyone should drop what they have now in favor of them. I do however feel that neutrals have been found. My efforts now will be in the area of texture and top coatings, I have no desire to create a new mix or mix a new gray that area is already covered by some very talented people.
(I will add some graphs and charts later on after work to hopefully make this a more enjoyable read...)