does having gray screen improve blacks in a light controlled room? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 39 Old 03-18-2017, 07:02 AM - Thread Starter
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does having gray screen improve blacks in a light controlled room?

this is my first time posting but have read a lot of the posts on this site, that said, I still am a little confused with the gray vs. white screen. I understand that gray is better for low light rooms for contrast, but wouldnt it also be better for dark rooms? I guess my question would be why use the white screen in any condition? since gray gives better contrast, better blacks.
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post #2 of 39 Old 03-18-2017, 07:34 AM
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Gray screens do not give better contrast, they lower black levels but also lowers white levels and contrast stays the same. This can be beneficial if your projector has poor black levels with enough brightness that the white won't look dim.

Ambient Light Rejecting screens will give better contrast with ambient light or reflections but add artifacts, so it is a tradeoff.
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post #3 of 39 Old 03-18-2017, 09:06 PM
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Originally Posted by B.D View Post
this is my first time posting but have read a lot of the posts on this site, that said, I still am a little confused with the gray vs. white screen. I understand that gray is better for low light rooms for contrast, but wouldnt it also be better for dark rooms? I guess my question would be why use the white screen in any condition? since gray gives better contrast, better blacks.
If your room is a perfect "bat cave" with no ambient light and 0 reflections from the ceiling and walls, you should use a matte white screen. However, in pracice even dark coloured walls will reflect some light (check the light reflectance value LRV of the paint). In those cases, you will get better intra-scene contrast (e.g., when displaying a checkerboard patern) with a grey screen. Note, however, the inter-scene contrast ("on/off contrast") is determined by the projector and not by the screen.

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post #4 of 39 Old 03-19-2017, 04:59 AM
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Originally Posted by B.D View Post
this is my first time posting but have read a lot of the posts on this site, that said, I still am a little confused with the gray vs. white screen. I understand that gray is better for low light rooms for contrast, but wouldnt it also be better for dark rooms? I guess my question would be why use the white screen in any condition? since gray gives better contrast, better blacks.
Ellebob and Domimic are absolutely correct about projection light striking the screen for the first time. A neutral gray will reduce all light of all colors equally and proportionally in all regards and will maintain the same CR when calibrated to return the exact same image in terms of returning brightness measured in FL (foot Lamberts) or lumens per sq foot.

The simple example I will make is what I use at home in my media room. My screen is 50% gray so in terms of a 1.0 gain white screen (unity gain) my screen is a .5 gain. In my case to get the returning FL I want for my given size screen if it was white I would need 1000 lumens but because I have a .5 gain gray I hit mine with 2000 lumens. In a pitch black room with no light coming in and every item in that room painted flat black or draped in black velvet, the two images would be exactly the same.

Very few rooms are that perfect though. And projected light hits the screen and displays the image to the whole room. You only see the small amount of that light that goes into the opening of your eye and falls on your optic nerve. If you are the only person in the room just what goes in your two eyes is needed it is nice it goes all over in case you move around of have 500 other people watching like in a movie theater. But even then the rest is wasted. What happens to it is the question. If it strikes a piece of black velvet it is 99.9% sucked into the velvet and converted to heat. If it strikes a 50% neutral gray wall 50% is converted to heat and 50% bounces back into the room. If it hits a white wall almost all of it returns to the room. Some of that bouncing around in the room will find its way back to the screen and is now ambient light no different than a window or a light bulb turned on in the room. That light striking the screen goes into direct competition with the projected light and diminishes “waters down” the CR the projector is producing.

Another way to think of it is that projectors do not project black. What they do when a area on the screen calls for black is to try and project no light. A very dark color projects almost nothing with a slight bit of color. If you measure the lumens hitting the screen where it is trying to be black it will measure very little so you can see if another area on the screen is white and lighting up the room the ambient level could be high and it takes very little of it to dilute a black that is no light. The deepest black a screen can produce will be what the screen looks like with whatever ambient is in the room. It is not just black that gets diluted by ambient light adding brightness to all colors changes them from what they should be it is just the dark colors we notice going away the fastest.

That’s the short answer as others have posted and now there is a bit more to the long answer. It is the term you will hear a lot but seldom see explained. It is also harder to grasp maybe, but is very important.

It is called perception of contrast and how our eyes work in seeing and processing contrast. Millions of years of evolution of how humans see gave us the ability to see on the darkest of moonless nights and also out in the brightest summer sun lit days. If you took a light meter out and measured the light levels where our eyes work you would find the level increases something like a million times. The way we can do that without burning out our eyes that our eyes adjust instantly as the iris changes size getting smaller as things get brighter. When we watch a projected image nature takes over and when the screen is very bright like watching a sporting event our iris adjust and get smaller limiting the amount of light coming in. The level gets adjusted on the overall brightness in our field of vision and areas that try to be black are perceived as blacker because the overall light coming back from the black area on the screen is cut back along with the brightness and we see the black as darker than it is if we took a light meter to the screen and measured it. One think to always remember is our eyes are amazing devices, but they are the worlds worst light meters because they are always changing trying to give us the best image possible.

Some people like me have dark gray screens and dark light absorbing walls and ceilings making our rooms well suited for a white screen but still use gray because no room is perfect first, and second we like to turn some task lights on so when watching sports or regular TV we feel like we are in more of a living room or sports bar lighting than pitch black like a movie theater. We can still kill the task lights for a movie experience if we want and the gray screen hurts nothing and helps with reflected ambient. When I want to have a sports viewing with a bunch of people coming and going and eating and drinking I do two things. I turn up the ambient task lighting so the room isn’t pitch black, and I also select a preset on my projector that makes it brighter. The brighter setting on already bright content forces perception of contrast and the dark screen and walls work to preserve contrast.

The only drawback to such a setup is I need a much brighter projector than I would in a dedicated lights out theater. Brighter projectors we used to call light cannons are sometimes not the cream of the crop in terms of all the advanced features and sometimes are more like business projectors that favor brightness over accuracy. There is a trend though going brighter and there are quality projectors that are very bright also. And of course screen size plays a part.


On edit:

In my above example I neglected to explain that with my .5 gain gray screen that absorbs half the projected light coming to it. It also absorbs half the ambient light coming to it. So in the case of my room with a black ceiling and 50% gray walls rebound ambient light leaves the screen and any that hits my ceiling gets mostly absorbed maybe 90% of it. 10% goes into the room and some part of that back to the screen what does hit the screen half again is absorbed. With my walls it come off the screen and the walls trap half and the other half lights up the room most of that bounces around the room getting halved each time and the little bit that returns to the screen is only half the effect on PQ reduction. The room and the screen is a light trap.


Welcome to the forum and a very good first post. Don’t be a stranger.
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post #5 of 39 Old 03-20-2017, 07:44 AM
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A grey screen improves simultaneous contrast if when watching a movie you can turn you head and see the room rather than pitch blackness. If you can see the room its reflecting light including back onto the screen. Each time that unwanted light hits a low gain grey screen its reduced before reflecting back into the room again, to reflect again off the room on to the screen, and so on. The screen is one of the things that limits in room simultaneous checker board contrast because its part of the rooms surface area.

The problem with grey screens is they are not as forgiving as far as screen imperfections and visibility of surface. They maybe less good at producing bright white and vivid colour or may tint the image. And you need a higher lumen projector to produce the same screen luminance.

Also on some projectors closing down an iris increases the projector's contrast while reducing lumen output. So a grey screen reduces the amount the projector's iris can be used to improve contrast.

Then there is the issue that viewer contrast sensitivity increases with increased image brightness. With two images of the same contrast but different brightness the brighter image looks higher contrast as long as black is not too high. And a similar effects applies to increased image contrast. With two images of the same brightness but different contrast the higher contrast image looks brighter as long as its not too dim. So it is possible a higher contrast but dimmer image might look like it has lower contrast than a brighter but lower contrast image.
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post #6 of 39 Old 03-20-2017, 09:17 AM
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Originally Posted by dovercat View Post
... They maybe less good at producing bright white and vivid colour or may tint the image. ...
By definition a 100% neutral matte screen, whether white or grey, will not "tint the image." The fact is that both white and grey screens can tint the image if they're not neutral. However, isn't it inaccurate to imply that grey screens tint the image more than white screens when independent screen testing has shown that many white as well as grey screens are not 100% color neutral?

Also, can you explain why you believe that a neutral matte grey screen with, for example, 0.5 gain illuminated by 1,000 projector lumens would produce an image with any less bright whites or vivid colors than a neutral matte white screen with 1.0 gain illuminated by 500 projector lumens? This seems to defy the fundamental logic of screen gain.
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post #7 of 39 Old 03-20-2017, 10:07 AM
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Unfortunately there very few true low gain true neutral gray screens outside the DIY realm. A neutral gray screen can also only be neutral around any given color temp illuminate. My DIY screen is closer to neutral at 7500K than it is at 6500k so it could be said my screen has a cooler push at 6500K. some people like that in fact. That is also true of some of the commercial gray screens. But that doesn’t mean it couldn’t be controlled out of the process. With mixing paints and measuring outcomes it has been proven in the past in the DIY forum it is not that hard to tint a paint to reach a pretty exact neutral gray.

Don Stewart has mentioned to me they have a product they make from time to time that is a very close low gain neutral gray that has unity like light dispersing properties. They mainly invented the material for Disney and their 360 degree movies where one projector becomes the other projectors ambient light source.

Dovercat is correct if you are using a projector designed to be the very best in theater settings with dynamic iris and all that. Going with a neutral gray could be counterproductive as the projector design is optimized for a bat cave and cranking the brightness up and not using the iris just so you get lumens to fight ambient that’s not there wouldn’t be logical.

Most of the home theaters I see are built not so perfect and are many compromises. More living room than home theater. I’m a bit of a rare case and have been all along I have a room that would be perfect for a white screen and an expensive projector with all the bells and whistles. And without a doubt I would have a better image doing it that way, except for the fact I sometimes want to add task lighting back in for sports and TV so I don’t trip over the dog when going for another drink or pizza. Gray done that way is the best of both worlds as I can get.

The trend is brighter projectors with better True CR year to year. The combination of those type of projectors coming along is IMO letting projectors hold their own against monster flat panels, for a lot less cost.

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post #8 of 39 Old 03-20-2017, 12:56 PM
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Hi guys,
Don't want to derail the thread here but this discussion pertains to me. I impulse bought a Da Lite HD Progressive grey 0.6 screen at 110" My projector is Epson 2040 in Eco Cinema mode, which I think gives off just under 1100-1200 lumens. Projector will be 13 feet from screen. Place is somewhat light controlled, with ambient light for sports. I bought it because I thought it would help with the black levels of my projector.


What's your thought? Should I have gotten a higher gain screen or am I fine? I haven't put it together yet.

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post #9 of 39 Old 03-20-2017, 01:20 PM
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Originally Posted by eightninesuited View Post
Hi guys,
Don't want to derail the thread here but this discussion pertains to me. I impulse bought a Da Lite HD Progressive grey 0.6 screen at 110" My projector is Epson 2040 in Eco Cinema mode, which I think gives off just under 1100-1200 lumens. Projector will be 13 feet from screen. Place is somewhat light controlled, with ambient light for sports. I bought it because I thought it would help with the black levels of my projector.
As has been discussed in the previous posts, a grey screen will help with the black levels, assuming the limiting factor is the room light (either existing or reflected). If the limiting factor is the projector itself, the contrast ratio will remain the same with a grey screen; everything will just be proportionately dimmer.

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post #10 of 39 Old 03-20-2017, 01:41 PM
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So given what you know about my situation above, is my projector bright enough in eco cinema mode?
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post #11 of 39 Old 03-20-2017, 02:03 PM
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Hi guys,
Don't want to derail the thread here but this discussion pertains to me. I impulse bought a Da Lite HD Progressive grey 0.6 screen at 110" My projector is Epson 2040 in Eco Cinema mode, which I think gives off just under 1100-1200 lumens. Projector will be 13 feet from screen. Place is somewhat light controlled, with ambient light for sports. I bought it because I thought it would help with the black levels of my projector.


What's your thought? Should I have gotten a higher gain screen or am I fine? I haven't put it together yet.
A 110” 16:9 screen is 36 sq ft. lumens/sq ft = Foot Lamberts. 1200/36=33.33 FL striking the screen. Your gray screen is .6 gain so 40% of the projector light will be attenuated by the screen 33.33x.6=20 FL returning to your eyes. Movie theaters shoot for 12-15 FL so you should have a nice bright image and get a hint of improvement with perceived contrast as well.

If you want the room to have more task lighting you can switch your projector off eco mode. Task lighting should be controlled and directed to the tasks and away from the screen as much as possible.

I think you should be ok. Tell us how it works.

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post #12 of 39 Old 03-20-2017, 02:32 PM
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By definition a 100% neutral matte screen, whether white or grey, will not "tint the image." The fact is that both white and grey screens can tint the image if they're not neutral. However, isn't it inaccurate to imply that grey screens tint the image more than white screens when independent screen testing has shown that many white as well as grey screens are not 100% color neutral?
I used the word "may" not does or always.

I do not know what modern screens are like but years ago...
I think it was common for white screens to have a slight push to red, with blue a tiny bit lower than red, and green a bit lower still. While grey screens like the early versions of grey hawk and fire hawk I think were blue highest, followed by red, followed by green.

A slight red push is attractive to the eye and can look natural. It is also the reverse to lamp based projectors which typically are red limited and as the lamp ages and red dims faster than green become green excessive.

While a blue push tends to look brighter but less natural and desaturates the image. Maybe because blue is a brighter colour than red and there is more blue in the mix that makes white than red. Maybe because the video standards use a greyscale already pushed to blue as a means of increasing the brightness of early cathode ray tube TVs.

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Also, can you explain why you believe that a neutral matte grey screen with, for example, 0.5 gain illuminated by 1,000 projector lumens would produce an image with any less bright whites or vivid colors than a neutral matte white screen with 1.0 gain illuminated by 500 projector lumens? This seems to defy the fundamental logic of screen gain.
Don't know. Maybe its because the white screen is part of the room surface area so increases room reflectance. So a white screen will be brighter due to more light bouncing around the room hitting the screen. Maybe because of the surround effect on perceived image contrast. A lower gain grey screen produces less light bouncing around the room which produces a darker surround, and a darker surround reduces perceived image contrast.
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post #13 of 39 Old 03-20-2017, 03:23 PM
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OK, so if white screens may also not be 100% color accurate there's no reason to single out grey screens to be avoided because they might also be color inaccurate. Testing has shown that many white and grey screens are designed to push blue because it's perceived as brighter and typical viewers tend to prefer a brighter image. Many viewers also prefer blue push because they've become accustomed to blue push from LCD TVs in their brighter modes. For many the D65 of Rec 709 appears to have an orange push because their eyes have been accustomed to blue push.

A lower gain grey screen does not produce less light bouncing around the room if projector lumens are adjusted higher to match a 1.0 gain white screen, so it would not produce a darker surround and would not reduce perceived image contrast. There is absolutely no difference in image brightness between a 0.5 gain neutral matte grey screen with 1,000 projector lumens and a 1.0 gain neutral matte white screen with 500 projector lumens. Both screens will reflect exactly the same amount of projector lumens. However, since you have doubled projector lumens while reflected light lumens from the screen remain the same, you have increased projector lumens to reflected light lumens coming back onto the screen by a factor of 2, resulting in less image washout from reflected light.

That's the true benefit of a neutral matte grey screen. There are no negatives compared with a comparable matte white screen as long as your projector has adequate lumens to properly illuminate the grey screen to the same level as the white screen and the grey screen is equally color neutral.
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post #14 of 39 Old 03-20-2017, 04:24 PM
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Originally Posted by Dave in Green View Post
OK, so if white screens may also not be 100% color accurate there's no reason to single out grey screens to be avoided because they might also be color inaccurate. Testing has shown that many white and grey screens are designed to push blue because it's perceived as brighter and typical viewers tend to prefer a brighter image. Many viewers also prefer blue push because they've become accustomed to blue push from LCD TVs in their brighter modes. For many the D65 of Rec 709 appears to have an orange push because their eyes have been accustomed to blue push.

A lower gain grey screen does not produce less light bouncing around the room if projector lumens are adjusted higher to match a 1.0 gain white screen, so it would not produce a darker surround and would not reduce perceived image contrast. There is absolutely no difference in image brightness between a 0.5 gain neutral matte grey screen with 1,000 projector lumens and a 1.0 gain neutral matte white screen with 500 projector lumens. Both screens will reflect exactly the same amount of projector lumens. However, since you have doubled projector lumens while reflected light lumens from the screen remain the same, you have increased projector lumens to reflected light lumens coming back onto the screen by a factor of 2, resulting in less image washout from reflected light.

That's the true benefit of a neutral matte grey screen. There are no negatives compared with a comparable matte white screen as long as your projector has adequate lumens to properly illuminate the grey screen to the same level as the white screen and the grey screen is equally color neutral.
With knowing all the above to be true for the last 12 years I have been studying this stuff. I always found it hard to believe most people still are of the mindset that white is the best screen surface and any simple negative gain neutral gray is just a patch for an inferior projector and often hear how they produce muddy whites. Very few low gain neutral gray commercial screens are out there and the ones that are seem to be in the .8-.9 range.
Often when people match a bright projector to a small screen the go to solution is a neutral density filter and a white screen again.

I still get comments on my screen where people say when seeing it “oh I didn’t know you could use a projector with the lights on”.

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post #15 of 39 Old 03-20-2017, 04:56 PM
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Originally Posted by Dave in Green View Post
OK, so if white screens may also not be 100% color accurate there's no reason to single out grey screens to be avoided because they might also be color inaccurate. Testing has shown that many white and grey screens are designed to push blue because it's perceived as brighter and typical viewers tend to prefer a brighter image
Which white projector screens have push blue more than red?

I do not know about your eyes but a slight red push looks better than a blue push to me. As lamp based projectors are typically red limited I think its also better as far as getting calibrated dynamic range out of the projector.

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A lower gain grey screen does not produce less light bouncing around the room
Yes it does because light does not get reflected once then cease to exist and the screen itself is part of the surface area of the room that re-reflects light bouncing around the room. Each time light hits a grey screen it gets reduced.
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post #16 of 39 Old 03-20-2017, 06:13 PM
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With knowing all the above to be true for the last 12 years I have been studying this stuff. I always found it hard to believe most people still are of the mindset that white is the best screen surface and any simple negative gain neutral gray is just a patch for an inferior projector and often hear how they produce muddy whites. Very few low gain neutral gray commercial screens are out there and the ones that are seem to be in the .8-.9 range.
Often when people match a bright projector to a small screen the go to solution is a neutral density filter and a white screen again.

I still get comments on my screen where people say when seeing it “oh I didn’t know you could use a projector with the lights on”.
While an ND filter lacks the benefits of a grey screen it is easier. Less problematic as far getting a DIY paint close as possible to a very low gain neutral grey and perfectly flat screen surface, and as the lamp dims the ND filter can be removed.

As far as projecting with lights on I think I prefer extra image brightness, a display in a living room is typically about what 23 to 35 foot lamberts. Very good black level I would have thought is not important if say watching sports or bright TV shows or bright films. And achieving very good black level I would expect is basically impossible unless the screen is near black. A cinema has ambient light hitting the screen of about 0.1 lumen per square foot, a dimly lit room about 1 to 2, a normally lit room about 30 to 60. To achieve the lumen and the black level it looks to me like either a light cannon and near black screen or a fancy expensive black screen with gain and off axis light rejection or a rear projection setup, could be needed.

I am afraid I am not a convert to grey screens. I currently use a white painted wall and the only commercial screens I have owned have been white with a little bit of gain or high 2.5 gain. I am using a projector that claims it can output upto 7,500:1 contrast at 500 lumen to 1,200:1 contrast at 4,300 lumen depending on lamp and iris settings. My screen is 125.375 inch diagonal 16:9. The room is light controlled and black except for a few movie posters
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Originally Posted by dovercat View Post
Which white projector screens have push blue more than red?
I've seen this mentioned in several different screen tests. One that comes to mind is the screen comparison review at thewirecutter.com which noted:

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The most common flaw with the screens we tested is that they introduce a blue tint to the projected image. A bluish-white looks brighter than a neutral D65 white (the correct white point for home video content). If you see two screens side by side and one looks brighter, you often can’t tell which one is “correct,” but your eye will tend to prefer the brighter one. If you see a screen by itself, your eyes and brain will adjust to the incorrect image and assume it is correct. This blue tint is present in all the cheaper screens, which use similar materials, so one with a minimal amount is what we looked for.
Link: thewirecutter.com/reviews/best-projector-screen/

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I do not know about your eyes but a slight red push looks better than a blue push to me. As lamp based projectors are typically red limited I think its also better as far as getting calibrated dynamic range out of the projector.
I wasn't talking about my eyes. I personally prefer D65. I was speaking of typical viewers raised on a steady diet of blue push from bright LCD TVs prefering blue push in projector images to get a brighter perceived image.

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Yes it does because light does not get reflected once then cease to exist and the screen itself is part of the surface area of the room that re-reflects light bouncing around the room. Each time light hits a grey screen it gets reduced.
Oh, sure, in theory image light reflected off the screen onto room surfaces and back onto the screen is then reflected back onto the room surfaces again. However, in reality, by then the amount is so miniscule that it's negligible and likely not noticeable to the human eye.
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post #18 of 39 Old 03-20-2017, 09:16 PM
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Oh, sure, in theory image light reflected off the screen onto room surfaces and back onto the screen is then reflected back onto the room surfaces again. However, in reality, by then the amount is so miniscule that it's negligible and likely not noticeable to the human eye.
Just to put the statement in context: the "minuscule" amount of reflected light refers to the effect on the white parts of the projected image. It can signicantly raise the black levels, and is the main reason grey screens can improve the contrast (by reducing the reflected light).

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post #19 of 39 Old 03-21-2017, 04:27 AM
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While an ND filter lacks the benefits of a grey screen it is easier. Less problematic as far getting a DIY paint close as possible to a very low gain neutral grey and perfectly flat screen surface, and as the lamp dims the ND filter can be removed.

As far as projecting with lights on I think I prefer extra image brightness, a display in a living room is typically about what 23 to 35 foot lamberts. Very good black level I would have thought is not important if say watching sports or bright TV shows or bright films. And achieving very good black level I would expect is basically impossible unless the screen is near black. A cinema has ambient light hitting the screen of about 0.1 lumen per square foot, a dimly lit room about 1 to 2, a normally lit room about 30 to 60. To achieve the lumen and the black level it looks to me like either a light cannon and near black screen or a fancy expensive black screen with gain and off axis light rejection or a rear projection setup, could be needed.

I am afraid I am not a convert to grey screens. I currently use a white painted wall and the only commercial screens I have owned have been white with a little bit of gain or high 2.5 gain. I am using a projector that claims it can output upto 7,500:1 contrast at 500 lumen to 1,200:1 contrast at 4,300 lumen depending on lamp and iris settings. My screen is 125.375 inch diagonal 16:9. The room is light controlled and black except for a few movie posters
Like you I have a projector with a wide swing in lumens and CR. Combined with that at my brightest setting color accuracy drops off.

I prefer both the benefits of a neutral gray and the benefits of increased lumens when dealing with desired ambient lighting. The classic 15FL is ok with viewing in my room lights out my “cinema mode” but I find 20FL is even better (pop) and gives what I call a poor man’s HDR 20-25FL. I can do all 3 and do depending on mood all with all lights off on the .5 gain gray screen. When I start turning up the house lights for sports viewing with a bunch of people moving about and socializing it is more about CR real and perceived and less about black levels and color accuracy as you mentioned as most of the image is bright colors without a lot of large black ANSI like areas even. I’m ok with boasting the returning FL as far as I want to go.

With my RGBCYW projector and keeping my screen size down to 100”-110” I have 1000 lumens of good RGB color output for movies. I have 1000-2000 lumens of very acceptable but not perfectly accurate light using the brilliant colors settings and the supplemental CYW colors to a larger extent. If I want to go for lumens and blow thru a lot of ambient to get the most detail possible disregarding colors accuracy I can max out at 3300 lumens per the manufacture. I rarely go up there but if given that much ambient requirement or I really want to take the screen size huge those setting give a better image than I would get competing against the ambient with lower but better lumens. Here is the thing when this type projector is measure in these setting the results are the worst readings the testers have ever seen in their life and the testers quickly dismiss the projector as garbage when comparing it to very accurate HT projectors where color calibration is everything and they are dealing with a perfect white screen in a perfect dark room. In reality the PQ is not fantastic I admit in the torch settings but it is very ok to watch given the environment it is competing with.

In my room my perfect setup would be two projectors and two screens. A very accurate HT projector with an iris and a quality unity white screen. The second projector would be a light cannon and a painted dark gray screen wall behind the white screen. It would take the mundane daily usage off the HT projector and provide the best of both worlds in one room. I actually can get pretty close to that with the one cheap projector and screen setup and it is good enough for me at this time. My judging point for good enough is if my home image looks as good or better than the local Tinsel Town Theater. I’m at least that good when I’m in cinema mode so I say good enough.

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post #20 of 39 Old 03-21-2017, 06:27 AM
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Originally Posted by Dominic Chan View Post
Just to put the statement in context: the "minuscule" amount of reflected light refers to the effect on the white parts of the projected image. It can signicantly raise the black levels, and is the main reason grey screens can improve the contrast (by reducing the reflected light).
I agree with your point within your context, which is different from my original context. To be clear, the context of my "miniscule" comment was in reference to @dovercat 's mention of the third reflection -- the screen image light reflected onto light colored room surfaces, re-reflected back onto the screen, and then reflected a third time back onto room surfaces. Theoretically this re-reflecting occurs into infinity. Realistically the effect of the third reflection and beyond is miniscule to the human eye.
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Originally Posted by Dave in Green View Post
I agree with your point within your context, which is different from my original context. To be clear, the context of my "miniscule" comment was in reference to @dovercat 's mention of the third reflection -- the screen image light reflected onto light colored room surfaces, re-reflected back onto the screen, and then reflected a third time back onto room surfaces. Theoretically this re-reflecting occurs into infinity. Realistically the effect of the third reflection and beyond is miniscule to the human eye.
The amount the 3rd 4th , 5th …. Reflection diminishes to zero is totally dependent on how much each interaction attenuates. In my case of 50% screen and 50% walls it is fairly easy to compute the rate of decline if you think all the light striking the wall returns to the screen. But only a small amount of what hits the wall returns to the screen in a retroreflective direction because of the geometry of the room and the sheen of the particular wall paint most strikes the wall at an angle and some gets absorbed and some gets skipped off deeper in the room. I have often thought satin finish or semi-gloss would improve side wall reflections for that reason. Velvet works best because 2nd 3rd 4th etc. all take place in the fiber without reentering the room.

I suppose a room could be tested for its ability to attenuate light. But as mentioned before a good test is to look around the room during a bright image and notice how much the room has lit up.

I reflect my image off a mirror and the mirror attenuates very little light. I know the stray light and the lens bloom all happen away from the screen with that setup. It seems to help. But then again I have a mirror on the back of my room so projector light coming out is going to hit that mirror and become washout ambient. I believe the net result is a wash with that setup maybe.

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post #22 of 39 Old 03-21-2017, 04:08 PM
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I've seen this mentioned in several different screen tests. One that comes to mind is the screen comparison review at thewirecutter.com which noted:

Link: thewirecutter.com/reviews/best-projector-screen/
So white cheap monoprice screens, enthusiast company made silver ticket screens, DIY Wilsonart designer paint screens. Not major brand white screens Stewart, Da-lite, Carada.
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Oh, sure, in theory image light reflected off the screen onto room surfaces and back onto the screen is then reflected back onto the room surfaces again. However, in reality, by then the amount is so miniscule that it's negligible and likely not noticeable to the human eye.
I am not sure it is a minuscule negligible difference that is likely not noticeable to the human eye. Using your example of a 0.5 gain grey screen vs a 1 gain white screen. If the screen occupies 7.5% of the room's surface area and the rest of the room is covered in black paint reflectance 5%. Just counting the cumulative light bouncing around the room from the first, second, third reflectance. The room with the 1 gain white screen has I think about 24% more light bouncing around it than the room with the 0.5 gain grey screen. So the surround is going to be 24% brighter. The same thing that enables grey screens to boost on screen contrast by reducing unwanted 2nd, 3rd, etc reflectance also reduces the amount of light bouncing around the room that lights up the rest of the room.
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Originally Posted by dovercat View Post
I am not sure it is a minuscule negligible difference that is likely not noticeable to the human eye. Using your example of a 0.5 gain grey screen vs a 1 gain white screen. If the screen occupies 7.5% of the room's surface area and the rest of the room is covered in black paint reflectance 5%. Just counting the cumulative light bouncing around the room from the first, second, third reflectance. The room with the 1 gain white screen has I think about 24% more light bouncing around it than the room with the 0.5 gain grey screen. So the surround is going to be 24% brighter. The same thing that enables grey screens to boost on screen contrast by reducing unwanted 2nd, 3rd, etc reflectance also reduces the amount of light bouncing around the room that lights up the rest of the room.
I don't really agree with your math, but regardless, light that is being bounced around does not make the image look brighter; it only kills the contrast.

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Wow, just wow. This thread is equal parts incredibly illuminating, pun intended, and incredibly disheartening, at least to a noob like me.

I truly appreciate the OP's question and the amazingly well thought out and very informative answers.

But please don't mind me saying, this really is rocket science and seems super easy to spend gobs of dough and be unhappy with the result.

I recently visited Value Electronics in Scarsdale, NY, home of the well known flat panel shootouts reported here. In the rear they have a theater and it is very impressive.

And yet, a good buddy of mine, about 3 or so years ago, had set up in his light controlled basement (Wall painted flat black behind a 110 or 120" screen, not sure of exact size,) with the then top of the line Epson 5030, decidedly gray, not white at all. I know he paid a considerable sum for it, perhaps upwards of 3-5k. It's fixed against the wall.

While I can't say I've ever watched it with all lights out (there are no windows), I've never been in any way impressed by it. Picture isn't sharp, isn't bright, and I'd rather watch my 75" Samsung.

That scares me, rightly or wrongly.

Currently I'm building an addition, media room, 23' x 23', walls 8' to a 15' cathedral ceiling. I want a projector and screen but am leaning toward an 85" flat panel just because this is rocket science, at least to me.
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Originally Posted by MDJAK View Post
Wow, just wow. This thread is equal parts incredibly illuminating, pun intended, and incredibly disheartening, at least to a noob like me.

I truly appreciate the OP's question and the amazingly well thought out and very informative answers.

But please don't mind me saying, this really is rocket science and seems super easy to spend gobs of dough and be unhappy with the result.

I recently visited Value Electronics in Scarsdale, NY, home of the well known flat panel shootouts reported here. In the rear they have a theater and it is very impressive.

And yet, a good buddy of mine, about 3 or so years ago, had set up in his light controlled basement (Wall painted flat black behind a 110 or 120" screen, not sure of exact size,) with the then top of the line Epson 5030, decidedly gray, not white at all. I know he paid a considerable sum for it, perhaps upwards of 3-5k. It's fixed against the wall.

While I can't say I've ever watched it with all lights out (there are no windows), I've never been in any way impressed by it. Picture isn't sharp, isn't bright, and I'd rather watch my 75" Samsung.

That scares me, rightly or wrongly.

Currently I'm building an addition, media room, 23' x 23', walls 8' to a 15' cathedral ceiling. I want a projector and screen but am leaning toward an 85" flat panel just because this is rocket science, at least to me.
Mark
Depends on how his projector was calibrated. You may want to use your projector on high lamp with your iris fully open. Maybe his was fully closed on eco mode?

I will tell you right now with my RS500, it destroys my 75'' 4k set in my family room. Anyone who comes over would much rather watch in my theater than my 4k set.

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Originally Posted by Dominic Chan View Post
I don't really agree with your math, but regardless, light that is being bounced around does not make the image look brighter; it only kills the contrast.
Just as a gray screen reduces white to black equally adding a wash of white light across a screen will raise the white and black levels equally.

Ambient light leaving the screen and bouncing around the room isn’t white necessarily. And if it is white it will be altered depending on the color of the surface it reflects off. Blue paint looks blue because it absorbs all the rest of the spectrum and reflects blue. So, if your side walls are painted blue it is likely to raise the blue push on your image just like adding a blue filter to a white lamp. Paint is just a filter. Part of the reason I painted my whole room a neutral gray and my ceiling black. I thought about an all-black room but as we do use the room for other uses I did want to maintain the ability to light it up somehow and not be too depressing when not watching a movie. 50% gray makes short work of rebound ambient light and is a good compromise.

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post #27 of 39 Old Yesterday, 04:45 AM
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Originally Posted by MDJAK View Post
Wow, just wow. This thread is equal parts incredibly illuminating, pun intended, and incredibly disheartening, at least to a noob like me.

I truly appreciate the OP's question and the amazingly well thought out and very informative answers.

But please don't mind me saying, this really is rocket science and seems super easy to spend gobs of dough and be unhappy with the result.

I recently visited Value Electronics in Scarsdale, NY, home of the well known flat panel shootouts reported here. In the rear they have a theater and it is very impressive.

And yet, a good buddy of mine, about 3 or so years ago, had set up in his light controlled basement (Wall painted flat black behind a 110 or 120" screen, not sure of exact size,) with the then top of the line Epson 5030, decidedly gray, not white at all. I know he paid a considerable sum for it, perhaps upwards of 3-5k. It's fixed against the wall.

While I can't say I've ever watched it with all lights out (there are no windows), I've never been in any way impressed by it. Picture isn't sharp, isn't bright, and I'd rather watch my 75" Samsung.

That scares me, rightly or wrongly.

Currently I'm building an addition, media room, 23' x 23', walls 8' to a 15' cathedral ceiling. I want a projector and screen but am leaning toward an 85" flat panel just because this is rocket science, at least to me.
Mark
Every hobby becomes rocket science at some point to some people. Look at the audio side of home entertainment if you want to see things go rocket science. Some people are happy with a sound bar or ear buds and others spent countless thousands of dollars on equipment and room design. I have mentioned before we did an A,B,C comparison between 3 different types of speaker wire one being $4 per foot one being cheap speaker wire and the third being Romax house wiring wire. None of the “experts” we had around here were sure what was what until they knew and then they could hear all kinds of improvement over the expensive wire.

The test I tell people thinking about front projection is go to the best digital theater in town and sit about 1/3 of the way back from the screen. Pick a movie that you know is shot without a lot of artistic license, just something with a known nice clean image. The PQ you see there will be a piece of cake to reproduce at home with an entry level projector sub $1000 and a reasonable attempt at keeping the room dark. Everything after that entry point into the hobby in terms of expense for projectors and room control dollar for dollar fall directly on the scale of diminishing returns, and take on more and more rocket science.

One last point on comparing flat panels and FP. They are not intended to be the same thing. FP is often described as filmlike. The term filmlike can mean a lot of things as your eyes are in a different state when watching a filmlike image but your brain is processing it as reality. A properly setup FP viewing is immersive and the screen surface vanishes and what you are seeing is like looking thru an open window a very large open window. In the case of Imax a window so large you can’t see the window frame. Flat panels have a far different look and are more eye candy. In many ways to me they look more real than reality. I am always aware there is a 2D surface the image is applied to, and they almost feel uncomfortable to watch with as much immersion as I would with FP. I think for me Imax level of immersion wouldn’t work at all for me. The trend is viewing these devices and a lot of people are losing their taste for filmlike. But just know the two are much different viewing experiences at least to me.
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post #28 of 39 Old Yesterday, 05:23 AM
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Depends on how his projector was calibrated. You may want to use your projector on high lamp with your iris fully open. Maybe his was fully closed on eco mode?

I will tell you right now with my RS500, it destroys my 75'' 4k set in my family room. Anyone who comes over would much rather watch in my theater than my 4k set.
I went to the Cleveland Home Show about a month ago and one of the demo houses was set up to showcase home media. In the living room they had a 85 inch flat panel and the house was arranged so you could see it from the living room kitchen and breakfast bar areas very easily. It was a beautiful display and was playing some real eye candy. Then they had a conventional FP home theater with a $40k projector fantastic sound, first class high dollar white reference screen and tiered seating with powered theater seating. They were running a short demo film they didn’t close the doors and had the room at a convenient light level for people to enter and exit and the PQ sucked after looking at that 85” eye popper.

When the guy asked if there were any questions one woman said “How much to put that TV in this room?” pointing to the big flat panel. He laughed and told her it would be 30k less, and she said I’ll take one.

I have no idea why they were downplaying the FP system that could have blown everyone away but no one could have afforded. I think the hassle of FP and that flat displays are a hang and watch solution are making projectors more of a niche market than they already are.

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post #29 of 39 Old Yesterday, 06:17 AM
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Just as a gray screen reduces white to black equally adding a wash of white light across a screen will raise the white and black levels equally.
Not really. Take an example where white is 100 and black is 0.1 without room reflection or ambient light. If the room reflection is equivalent to 1, white becomes 101 while black beomes 1.1. While you could say that white and black levels are raised "equally" (both by 1), that is not correct since the human vision is closer to logarithmic than to linear, meaning white level is essentially unchanged while black level is increased more than 10-fold.

This is totally unlike the case of grey screen, where white to black are reduced by the same ratio, rather than by the same offset amount.
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post #30 of 39 Old Yesterday, 07:50 AM
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Originally Posted by Dominic Chan View Post
Not really. Take an example where white is 100 and black is 0.1 without room reflection or ambient light. If the room reflection is equivalent to 1, white becomes 101 while black beomes 1.1. While you could say that white and black levels are raised "equally" (both by 1), that is not correct since the human vision is closer to logarithmic than to linear, meaning white level is essentially unchanged while black level is increased more than 10-fold.

This is totally unlike the case of grey screen, where white to black are reduced by the same ratio, rather than by the same offset amount.
I stand corrected I don’t know about the logarithmic part but in your example first case 100/.1 = 1000:1 CR and the second case 101/1.1 = 91.8:1 CR or slightly more than 10 fold.

You are increasing the white and black equally but are reducing the CR drastically.

Great point.

Bud
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