Gain and other confusing topics.

**wbassett** · **09-30-07, 10:55 PM**

Quote:

cynical2 wrote:

Freudian slip?

Nah, but I do see a major difference. Opaque and translucent materials will behave differently and have a different interaction with light. Nothing I am saying or making up, that's a fact and part of the physics of light and objects and how they interact.

I want to be clear on something, I acknowledge that commercial companies use mica based pearlescents to boost brightness and gain. I am saying we can't just dump things in and expect the same results as commercial screens. I also agree that just because something has pearl (mica) as part of the mix it shouldn't be discarded solely because of that... and no I'm not saying mixes should be discarded either.

We already know that yes, acceptable does work, but again I ask is DIY only shooting for 'acceptable' or are the developers shooting for the best? I consider myself a developer and I am striving for not only the best, but also to make things easy. I know some of these explanations seem complicated to many, but that's the behind the scenes testing and research that goes into easy. If it was as simple as going to the store and selecting a gray from a color swatch that looks 'good', then we'd have been done years ago. Acceptable and 'best', or optimal, are two different things to me. We have both and yes there is a viewable difference between them. To some it may not be enough to bother with, but again I ask if something is as easy as walking in and saying you want a certain color, how can that be considered hard or 'elitist'? It's not. It's a matter of information and education. The only way to show the difference is with testing and hard data. Well... yes our eyes can see it if given the comparison, but convincing people there is a difference and to actually do the comparison is the hard part. If they don't know or haven't compared things, it's hard to tell someone that one thing is better than another. That's why I like to have data to back things up.

The same goes with optic coatings. Yes there are present methods that will work and are acceptable, but there are also some other methods that are just as easy to obtain but yield even better results. So why stop at acceptable? The goal should be a method that increases detail, clarity, and color reproduction without altering the image. I do think we can do that. I don't think we can do that without some thought though.

What I would like to see are some tests done before and after the pearls are added to various mixes and top coatings to try and track any changes introduced and how much of a change and in what direction. That will be valuable information to have.

**Tiddler** · **10-01-07, 11:13 AM**

I agree with all of Bill's points in the previous post. As time goes on there will be better solutions dialed in properly with careful testing and backed up with measured color data. You can't just throw some pearl in polyurethane and expect to get the correct color balance or gain curves. There is a science to all this and my work was mostly trial and error and at that time the color data was suspect.

In the mean time the neutral gray proprietary tints like Gray Screen and Winter Mountain are excellent painted screen solutions and when those are not available the EasyFlex tints will yield reasonably good results for most modern projectors. As we know most of these new projectors can produce a nice image on a brown paper bag.

In short order I suspect the EasyFlex solutions will be rendered obsolete and that is a good thing. That means progress has been made and better solutions have been developed. DIY Screen technology has made a huge leap in the past few months and I am way out of my league now. The solutions that will be developed and identified by Bill and mechman in the next few months will leave EasyFlex in the dust. Those screen shots of the liquid aluminum screen Bill is working on demonstrates that clearly.

P.S My original posting was not very well worded and did not properly represent my thoughts on this subject.

**wbassett** · **10-01-07, 04:25 PM**

Quote:

tiddler wrote:

I agree with all of Bill's points in the previous post. As time goes on there will be better solutions dialed in properly with careful testing and backed up with measured color data.

In the mean time the neutral gray proprietary tints like Gray Screen and Winter Mountain are good beginner painted screen solutions and when those are not available the EasyFlex tints will yield reasonably good results for most modern projectors.

In short order I suspect the EasyFlex solutions will be rendered obsolete and that is a good thing. That means progress has been made and better solutions have been developed.

Honestly this isn't about rendering something obsolete, not to me at least. If we have something easily available, then why not use it?

You mentioned in the post before editing it that you tried to go with items easily obtained by anyone in the US, and that is an excellent mindset. I think though that you may have overlooked that we seem to have access to a wider variety of Home Repair centers that don't seem to be available to you. So what's easily obtainable for us seems difficult for you, and vice versa... you can easily obtain the pearlizing medium but many in the States can't seem to find it locally. Do-Able is another example. For those that can get it, it's incredibly easy and an outstanding screen. For those that can't, it really doesn't matter how good it is if they have no way to get it. In this case, at least people can order the pearlizing medium if they want it.

For those that only have a Home Depot available, your method is excellent. I recently ran into a site that someone created about how they did not have a Home Depot but did have a Sherwin Williams close by. Silver Screen was the rage, so they set about having a Sherwin Williams color match done. To me that makes very little sense. They could have went with a much better solution and in this case it would actually have been easier for them to get. To be fair, at the time that's all they may have known about.

As far as the expense, that may not be an issue at all. Gray Screen and Soothing White are not Duration exclusive. There is no reason why it can't be mixed using Luminous White as the base, but... I would personally want to get some first and spectro it to make sure of the balance. So to stay in line with my previous post, I am sure it would be 'acceptable' I wouldn't call it anything other than that until some readings were done.

Lowes can make anything from any company/brand. Still, I want to test those too. So I'm being equally as tough on the neutral grays as I may seem to be on everything else.

Easy is still easy to the end user. The behind the scenes testing to identify things is what's hard, but again, the end users don't have to worry about that.

As far as trying to improve things and make them better- Fashion Grey may actually be stepping down because we may have identified a better color balance. If that's the case, I call that progress. It still stays the same as far as ease of installation for a simple substrate one step method though; so nothing will change for someone wanting to use that particular method aside from a better recommendation is now being made. In the end, it is still just as easy. I really do try to adhere to KISS.

**wbassett** · **10-03-07, 03:42 PM**

This will be the last entry on the iridescence/mica topic unless anyone has any other comments or questions.

The main point I am making is a bit of caution is all. Also for people to keep in mind that craft paints are pretty low on the quality list of things and their tolerances and Quality Assurances aren't going to be as tight as other industries. If we think about it some, is a company going to spend a lot of money on tolerances on things that sell retail for a buck? Again, not slamming anyone, I am just saying we can only go so far with certain items.

I spoke to Da-Lite about this topic since they do indeed use mica in some of their screens. This is what they said:

Quote:

Alex at Da-Lite wrote:

I received the following reply from one of our chemists regarding our conversation, "You can rest assured the pearlescent we use shift the least amount of anything available. The primary factors effecting the shift (particle size, angle of light reflection, thickness of the interference coating on the pearlescent material, etc.) are all very carefully chosen, engineered and controlled by Da-Lite to produce the least amount of color shift possible for the desired optical effects designed into each screen surface."

("least amount of color shift possible"- meaning they also acknowledge even with proper control there is a color shift of some extent.)

So again, unless there are anymore comments or questions, I think it's safe to say yes it works but have some caution as to how much is used. The commercial companies confirmed exactly what I was saying previously and that is they adhere to very tight specifications that I seriously doubt we are going to get from the craft industry.

**wbassett** · **10-08-07, 09:26 PM**

Isn’t Color Color?

All televisions and projectors use the primary colors of red, green, and blue to create all of the colors in a video signal.

Some may be thinking right now “But I was told in grade school that the primary colors are yellow, red, and blue.” They are, but for paints and inks. They are two different color systems, one is additive (such as our projectors and TVs) and the other is subtractive, as mentioned paints for an example.

With paints what we see from the painted object is after the paint absorbs all the light other than the color it reflects back to our eyes. With additive colors, a specific wavelength or wavelengths are being created. The easiest way to think of this is with additive color (like our projectors), light is being created directly; with subtractive color, light is absorbed and reflected. We deal with additive colors with our projectors, and subtractive colors with our screens.

Because of the way the eye works, red, green, and blue are the colors projectors and TVs add together to create other colors. So in the additive system red and blue mix together for magenta- red and green mix together for yellow. By varying the amount and intensity of each color a display device can create different shades.

Color Spaces

So what is red and why? What looks red to one person may look reddish-orange to someone else. Color is in our heads and we are taught what they are. Because of this there needs to be a standard, otherwise every TV show, movie, printed media would all have different look and color depending on who was supervising the material, and in reality the broadcast system wouldn’t work. You certainly would not be able to adjust your set or projector because the very next channel or DVD you put in would not necessarily match the previous adjustments. Think about that for a moment and a world where every time you changed the channel you had to go through a color adjustment all over again. There wouldn’t be any calibration standards because it would again vary from person to person and company to company. See now how this would be a mess and why it was stated that without a set of standards things wouldn’t work?

In 1990 the Rec .709 (Recommendation ITU-R BT.709) which defined the exact red, green and blue points for broadcast and the HDTV standard. These point may look familiar to a few that have read some of the other threads throughout this forum… they are the ‘x’ and ‘y’ coordinates found on a CIE chromaticity diagram. The chromaticity diagram is a visual and numerical representation of color. Use it and you’ll never have to ask which way a color leans, you will be able to see it right away. In this sense the Yxy, or primarily the ‘x’ and ‘y’ values are better than sRGB numbers to determine the actual color shift we are looking at. RGB is a snapshot but the CIE diagram gives us a more complete picture.

With this specification in place content creators will know that their cameras will output a certain color, they can edit and correct those colors to a specific reference point, and the end result that we see is on our screen what was actually seen without any camera shift or biasing.

Without this specification and reference even within the CIE chromaticity diagram, people could pick their own ‘reference’ and we’d be back to having things all over the place. The movie and television industry settled on D65 as the neutral reference point and everything is keyed to that point. If every step in the chain follows this standard and reference point then what you see will be what the director intended. Sometimes directors do use different film stock and color techniques for a ‘unique’ look, some examples would be Sin City or 300, Charlies Angles to name a few... but they still reference the industry standard to ensure their ‘look’ will remain the same no matter where it is displayed.

That is why D65 is mentioned so much throughout this forum and why I use it as a reference point and target as well as what the industry shoots for. Certainly you can adjust your projector to a value that isn’t D65, but it will not display things they way they were intended to be seen nor will it be optimal.

So how can you tell if a neutral is 'neutral'?

I have seen some questions asking how one color can be said is neutral and another is not. First we have to state that there is a tolerance that determines if something is neutral and that is +/- .5 from zero based on the CIE L*ab readings, specifically the ‘a’ and ‘b’ values.

A CIE L*ab value of say 81 0 0 as referenced to D65 would be dead on neutral. If we had Yxy readings the same color would be 58.471096 .312712 .039008, which is the same, dead center neutral for D65, and that comes out to an sRGB value of 201 201 201.

That's some pretty tight specs and it means if we went with that then only that would be considered neutral, but there actually is a tolerance. That tolerance is +/- .5 from zero based on the L*ab readings. So these would be acceptable neutral readings: 81 .5 .5, 81 .5 0, 81 0 .5, 81 -.5 .5, 81 .5 -.5, 81 -.5 0, and 81 0 -.5 and everything in between the 0 to +/- .5 value. Still pretty tight but well within our neutral standard and goal.

I will say it again, there are many colors that we can use that will provide an acceptable image, but I was striving for optimal, or the 'best' when I decided to start researching neutral grays. Many have said it was the goal but too hard to achieve. We just weren't looking in the right areas or more important, at the numbers.

(Note: There are two values for Silver Screen listed, one is what Behr came up with, and the other is an independent source. We'll have new readings soon and compare everything and post the most consistent values.)

Of course the red dot in the center is D65. The next ring is the +/- .5 range. The next ring out was expanded to +/- 1 which is a near neutral, and the last ring is at +/- 2 which is starting to get into a caution zone. Depending on where a color is in the caution zone could be the difference between being able to calibrate with no apparent color shift or issue or having some problems with color shifting. We also have to take into consideration the projector and our eyes too. Some people may be able to see a color shift better than others.

One thing to mention about the chart is it uses the xy coordinates to plot color value, and I just expressed tolerances for L*ab notation. That’s fine because since we have standards we can convert back and forth between these color spaces and know we are talking about the same colors. There is a lot of math and science involved but I felt getting into math and equations was more than most want to read about.

Out side these tolerances, especially from +/-1 out are colors and not true neutrals or near neutrals. We do know there are colors outside the target that will work and provide a very nice image, but the closer we get to D65 the more accurate the color reproduction will be. To some this may be minute or they may not even see much of a difference, to others, they will see a big difference. As mentioned previously that has to do with the fact that our eyes are all different and we see colors different from one person to the next. That is also a reason why a color standard was developed.

So we can now 'see' where these colors fall in respect to our neutral reference point of D65, and depending on who's measurements you go with, Behr Silver Screen is a near neutral with one and in the caution zone with the other reading.

For lighter shades, we know they don't push as hard so the color shift isn't as harsh. The darker the color shade goes though, there will be shifting the further away from our neutral reference point that the color is.

Note: A true neutral is not actually a color.

For one of the best explanations of color spaces and neutral reference points check out the Whibal video here. I could go on and on about this citing from text books to various websites because there is much more involved than this brief overview, but Michael Tapes gives the easiest explanation I have seen, and it's kinda fun to watch too. Then again I could be a bit weird!

Also check out the next video that talks about color spaces and spectral curves, very good videos. For fun if you are still interested, check out why we need instruments when getting this precise and see how your eyes can lie to you.

A color is a hue and they absorb and reflect light differently than a neutral. A green color will absorb all of the light spectrum except for green which is reflected back and why we see it as green. A blue-gray or green-gray will reflect back a stronger blue or green reflected light which is why we see it as a blue or greenish gray color (Remember, neutral is not a color). This is where we get our color shifting from. Can we use non-neutrals? Absolutely and many are using them. It still doesn't deny the fact that the closer we pull things in towards our D65 neutral reference the better and more accurate the projectors colors will be as reproduced by the screen.

Hopefully this explained a little on color theory, why we have standards, and what constitutes a neutral value.

**mechman** · **10-08-07, 10:56 PM**

As always, excellent write up Bill!

mech

**prof55** · **10-14-07, 01:23 PM**

Let's revisit iridescence for a moment...

Your previous comments on color shifting and refraction of light are accurate, but they are all based on one premise: full spectrum white light. But this sort of light (except for ambient sources) is not present in a projection situation - the projector sends three colors, and all three are reasonably monochromatic. You can't change red, green, or blue into any other colors by refraction - or can you?

Garry

**wbassett** · **10-14-07, 01:54 PM**

I think we do all agree our projectors send three colors, red, green, and blue, and if only red green or blue were being projected we would have a pure color of one wavelength that is monochromatic, but rarely is just one color or wavelength being projected.

Plus we still have the issues of light going from one medium to another and when it passes though the denser mica platelets it gets bent and refracts. Even if the incoming light is of a pure nature and of a singular wavelength, it will still slow down and be 'bent' upon entering and exiting the denser mediums. If it is out of phase then it subtracts from our image, if it is in phase it will add or 're-enforce' the image. I don't think we are at any known level where we can actually engineer things to guarentee everything is in phase and additive.

Like I said before, we do know we can brighten things up some, all I was saying was for some caution to be used. You know how it can go, if one of something is good, two must be better, and before long four is said to be incredible and so on, and mica being an iridescent can have an affect on the image. Even if that affect is slight, would it not be better to look for something that doesn't have this as one of its characteristics? I think non-interference pigments and materials are a very interesting and virtually overlooked alternative.

**mechman** · **10-14-07, 04:54 PM**

Dr. Burrows has a PhD in all of this and consults with Da-Lite as well as other screen manufacturers and he does feel mica, aka iridescents can have a very negative affect on a projected image and if 'monochromatic' light was a non-issue he would have taken that into consideration.

Microscope images of SF and Silver - 200X:

Macro of S-I-L-V-E-R with a white uniform from a Minnesota Viking player:

I see the iridescence clearly. That's from the projector - no flash on a S-I-L-V-E-R panel.

So far the SF and the S-I-L-V-E-R remind me of a certain laminate which was a terrible hot spotter - Pearl Silver. Except Pearl Silver wasn't nearly as bad as these two under the microscope.

Of the three I'd take the Pearl Silver!

mech

**prof55** · **10-15-07, 01:00 PM**

Quote:

mechman wrote:

Dr. Burrows has a PhD in all of this and consults with Da-Lite as well as other screen manufacturers and he does feel mica, aka iridescents can have a very negative affect on a projected image and if 'monochromatic' light was a non-issue he would have taken that into consideration.

To me, brainstorming new ideas is the essence of DIY. Personally, I think we're capable of exceeding commercial screens, not just duplicating them. Sure, mica can cause problems - but so can virtually any ingredient. Besides, if I wanted the best Dr. Burrows has to offer, I'd just buy a Dalite.

Garry

**cynical2** · **10-15-07, 04:42 PM**

Quote:

prof55 wrote:

To me, brainstorming new ideas is the essence of DIY. Personally, I think we're capable of exceeding commercial screens, not just duplicating them. Sure, mica can cause problems - but so can virtually any ingredient. Besides, if I wanted the best Dr. Burrows has to offer, I'd just buy a Dalite.

Garry

Are you implying that you understand screen technology and the physics of colors (and light projection) better than a PhD that does this for a living? We're not talking about "other ingredients"...we're discussing mica. Burrows, with his experience/knowledge, clearly states that iridescence negatively impacts the image. Additionally, mech posted an image that demonstrates Burrows' conclusion. So, while the use of mica is widespread (I have it in the topcoat on my own screen), it seems pretty clear that it's use moving forward should be minimized to avoid image degradation.

It seems unbelievably optimistic to seriously believe that people at home, in their garages and basements, are going to "exceed" the R&D efforts at the major companies developing commercial screens. Together, these companies spend millions (tens of millions) of R&D dollars understanding and improving the technology. They do so in world-class laboratories using elaborate measurement devices...some of which cost more than the typical DIY'ers family car. They have a bevy of scientists that understand the science far better than the best the DIY community of hobbyists has to offer.

In short, it's not even a fair fight. You'd really have to believe that the scientists at these companies are idiots...that the intellect of the DIY community is so superior to that of the screen company scientists that it could make up for the huge deficit in lab facilities, measurement equipment, knowledge of the physics, and experience gained from developing screens full-time.

The DIY community can match/exceed simple commercial screen solutions, but simply doesn't have the mechanism to deliver alternatives to the more complex of commercial screens. Take a look under a microscope at the uniform laydown of glass beads in the HP screen for evidence...or the uniform textures created by fabric processing of commercial screens. The DIY'er simply can only play in one area...the screen companies can play anywhere that the physics takes them...they have the technology to enable just that.

**mechman** · **10-15-07, 05:03 PM**

Quote:

prof55 wrote:

To me, brainstorming new ideas is the essence of DIY.

We're not in disagreement there.

Personally, I think we're capable of exceeding commercial screens, not just duplicating them.

I've seen nothing that exceeds commercial yet.

Sure, mica can cause problems - but so can virtually any ingredient.

But mica is the problem at this point. It has been used to excess on many a DIY screen. And what is called "pop" by some folks is nothing but hot spotting. The sad part is that a lot of people went out and spent a lot of money on popsicle stick paint and Wagner power sprayers, for what? A screen that hot spots? DIY is much better off now that the horn has been pretty much silenced. One of the good things is that maybe more folks will hear of the things that Ben has done, rather than being drowned with the "All Mississippi All the Time"

Besides, if I wanted the best Dr. Burrows has to offer, I'd just buy a Dalite.

I could recommend one or two for you!

Garry

There's brainstorming going on. The difference is nobody wants to "toot their horn" until the solution is viable. We'd hate to have folks end up with a screen such as this panel:

And this particular panel exhibits the best uniformity of all the screen paint jobs I've seen. And this is after adjusting the contrast and brightness for the panel! Do you think we could recommend something like that? I'm hoping you're saying "no" right now!

Things need to be tested and that takes time. Otherwise you'd have folks running around screens that hot spot and they don't even realize it. They just tell folks that it's "pop"!

So in summary, we are in agreement that brainstorming is great for DIY and that mica, amongst other things, is bad for screens. But we disagree on whether or not it can get to the level of commercial screens. Although I am on the lookout for a quantum magnetic field generator on eBay!

Anyone know where I can pick one up for under $100? And that can align particles for at least a 120" screen? If you do pm me cause I don't want anyone else buying it before me!

mech

**prof55** · **10-15-07, 05:31 PM**

Quote:

cynical2 wrote:

Are you implying that you understand screen technology and the physics of colors (and light projection) better than a PhD that does this for a living? We're not talking about "other ingredients"...we're discussing mica. Burrows, with his experience/knowledge, clearly states that iridescence negatively impacts the image. Additionally, mech posted an image that demonstrates Burrows' conclusion. So, while the use of mica is widespread (I have it in the topcoat on my own screen), it seems pretty clear that it's use moving forward should be minimized to avoid image degradation.

No, at no point did I state that I understand anything better than a PhD, but neither do I believe that all innovations must come from a white coat with a million dollar budget. If Burrows and others are the "source of all knowledge", then why bother with a forum? So we can discuss their wisdom? Sorry, but I will continue to believe that us common folk are capable of independent thought, experimentation, and useful invention. If the goal is to copy commercial screens - while admitting our inability to do so - I guess I've opened my mouth in the wrong arena. My apologies.

Garry

**mechman** · **10-15-07, 06:44 PM**

Quote:

prof55 wrote:

If Burrows and others are the "source of all knowledge", then why bother with a forum?

Right now? To get to roughly 90% at about 10% of the cost.

So we can discuss their wisdom? Sorry, but I will continue to believe that us common folk are capable of independent thought, experimentation, and useful invention. If the goal is to copy commercial screens - while admitting our inability to do so - I guess I've opened my mouth in the wrong arena. My apologies.

Garry

I don't think we're capable of copying commercial screens. But I'm still working on the quantum magnetic field generator on eBay!

And no one's pm'd me yet either!

Seriously though, maybe one day someone can show me a DIY product that's as good as the commercial products I've seen (nudge, nudge Ben!). I'd love to see it happen! And at a DIY cost! The major players from the past haven't been able to convince me...

Watch for my debunking the bunk threads coming soon to HTS!

mech

**cynical2** · **10-15-07, 07:07 PM**

Quote:

prof55 wrote:

No, at no point did I state that I understand anything better than a PhD, but neither do I believe that all innovations must come from a white coat with a million dollar budget. If Burrows and others are the "source of all knowledge", then why bother with a forum? So we can discuss their wisdom? Sorry, but I will continue to believe that us common folk are capable of independent thought, experimentation, and useful invention. If the goal is to copy commercial screens - while admitting our inability to do so - I guess I've opened my mouth in the wrong arena. My apologies.

Garry

Nowhere did I say that we should copy what commercial screens are doing (though gaining inspiration from their technology is likely a good idea since they're doing what they do for a reason). Additionally, I didn't say that Burrows was the "source of all knowledge", nor do I believe that. But, I do have great respect for his knowledge and his accomplishments. However, your post came across (to me, at least) as dismissive of the foundation of knowledge and capability behind his comments...that you question his input. I tend to take the input of someone with his credentials as the gospel when he's commenting on his area of expertise, unless I have strong data that is to the contrary.

Your have confidence that the DIY community will exceed what he (and the industry, in general) has been able to develop. Perhaps I'm biased because I work in R&D for a huge company, and know the resources at my disposal compared to someone at home working in their garage...but I think that an expectation that the DIY community will exceed the performance of commercial screens is, generally speaking, unlikely. Not impossible, but very unlikely...

That being said, like you, I would LOVE to see it happen. After all, if it does, we all benefit. And I do think that we can develop screens that compete with commercial screens in some areas (e.g. non-advanced neutral greys). However, there will always be specialized, high $, commercial screens that we will never approach, IMO.

To me, the goal is simple...make the best screen out of widely available materials that we can, at a significant discount to the cost of commercial screens. These DIY concepts could use a similar approach to commercial screens, or could be a concept that is completely "out-of-the-box". If we can approach their level of performance at a small fraction of the cost, then I see that as success.

**wbassett** · **10-16-07, 01:57 AM**

Quote:

prof55 wrote:

No, at no point did I state that I understand anything better than a PhD, but neither do I believe that all innovations must come from a white coat with a million dollar budget. If Burrows and others are the "source of all knowledge", then why bother with a forum? So we can discuss their wisdom? Sorry, but I will continue to believe that us common folk are capable of independent thought, experimentation, and useful invention. If the goal is to copy commercial screens - while admitting our inability to do so - I guess I've opened my mouth in the wrong arena. My apologies.

Garry

My take and opinion is this... the white coats know something about all of this and we should look at what they are doing and listen to them.

I never said mica shouldn't be used, that is a misconception that some (not necessarily you) have said. What I did say is we probably should use a little caution.

We do know one thing right now that Da-Lite doesn't seem to agree with, and that is the Silver Matte is an excellent screen for us Home Theater users. We are trying to get them to re-evaluate that and re-badge it as a consumer HT screen along with the others in their line up, and they seem to be listening to user input, which is good. They developed it and saw it as a specific '3D' application, and us DIYers did testing and saw it has much more potential. That is definitely thinking outside the box and not conforming to the 'we said so' mantra that does happen in both the commercial world and DIY.

I think we can do some incredible things with DIY, but I also believe in my heart we can't just dump things together and call it a day. Some people do that, some actually try to research what will happen when things are mixed. So I am in agreement on both sides here, and yes I realize that sounds like I am fence riding but it's not. We do know from our own eyes and testing that iridescents can cause problems and that yes, some commercial companies do use them, but they have much more quality control than some of the things currently being used. Is that an 'elitist' attitude like someone has recently taken up to calling us, I don't think so.

Garry you know about the technical side of all of this, and I think you would agree nobody is saying everyone needs to run out and spend ton on a spectrophotometer. People can at least look at the data though (specs if you will) and be able to look at two different methods and make a decision based on more than just 'Empirical' testing. Now, that same Empirical testing is also needed but it is just a part of things. You and I did this with the laminates... I sorted though literally hundreds of samples from all the different manufacturers and narrowed them down and then we tested them and took readings. That sorting and evaluation stage was the 'Empirical testing'. Did we expect everyone to do their own spectro readings? Not at all. Did people respect the work and validating things? I think they did.

For some of us we do actually like standards and researching things. That's our fun we get out of this, but it doesn't mean everyone has to do that or that only certain methods are acceptable. There is a wide range of very good DIY methods out there, but I do think we can raise the bar and right now the only way to do that is with researching things and extensive testing. I don't think anyone would disagree with that. There are tons of fun things and very necessary things we need to look into with DIY and make better. Arguing over grays (again, not necessarily you) is a waste of time when we do have some excellent ones that anyone can literally walk into a variety of stores and just ask for and walk out with.

I'm on a rant and I apologize to everyone, but I really and truly do believe we have our grays and there is much more that we can be looking into and trying out to take things to the next level. Iridecents do give some increase in gain, but they also can be dangerous if used without some thought. Non-interference pigments and components, like I said previously have a completely different set of characteristics but seem to have been over looked by many. I have learned much from fellow DIYers over past year and a half, and I have also learned a 'little bit' from the college courses I have been taking on all of this. We can use our creative sides in DIY and then use the science to make sure it really works. Both go hand in hand to me.

**wbassett** · **10-18-07, 05:44 PM**

Grays again...

I see this come up over and over. Actually by now the real topic should be gray or white, and if gray what shade, not a constant debate about how to make them. That just seems counter-productive after awhile.

Neutral references and tolerances were already mentioned so there is no need to rehash that again.

So what does that have to do with gasoline? Just an analogy...

You pull into a gas station and see the price for both Regular and Premium are the same. We all know our car will run on regular, but the question is, if both were the same price, which one would you get? Now let's make this a little more interesting. The gas station down the street has Premium gasoline even cheaper. Now it's not a question of whether you'll pump the better grade gas or not, it's where you will get it.

It's still not as simple as that though. Say the cheaper gas price is at a station that for a personal reason you don't like. People boycott certain gas stations or stores all the time.

Now let's apply that analogy to our grays. Granted I don't know of anyone that boycotts a brand of paint, but some people do prefer one brand over another. As far as grays go, we know that unless the gray is some fancy hue meant for a pleasing decor look, it probably will work for a screen. Lots of things will work and I certainly am not saying they don't. The perception seems to be though that a D65 neutral gray is very difficult to get, and they are not. There are probably a dozen that have been identified right now, and more are on the way. These are not anything fancy or complicated at all, no mixing, no fuss. Just walk in and give the color code and name, and depending on the store, as little as $9 later you're walking out with a neutral base coat for your screen.

You could go look through the color swatches in the store and find a gray by a visual inspection, and yes it probably will work as a screen. The color balance and value though will be a complete unknown at that point, or we could say regular gasoline. My curiosity question though is if the same store sells one of the identified neutrals, and it costs the exact same price as the gray found by looking through the color swatches, what's the difference as far as just getting the one that was identified and measured as a neutral? It certainly isn't any harder to get.

I understand there may be situations where a person only has one paint store available. That would be a rare situation, but is a possibility. If that is the case, then you have to go with what you have available. For those that only have a Home Depot in their area, the EF tints are one way to go, and soon there will be Munsell color matches done for Glidden and Behr paints. For those with only a Lowes nearby, no worries, they can call up anything and mix it. I live in the sticks and have a Lowes, two Home Depots, ACE, several Sherwin Williams stores, and three True Values within a 20 mile radius. When in doubt, check their store locator. You may have something available that you never realized.

D65 neutral isn't about paint, it's the industry standard that everyone uses... from filming a movie or television show, to post production, and all the way through to our DVDs, players, Televisions, and projectors. Why stop there then? If everything else is keyed to D65, then why not our screens? Especially when we have them readily available.

In the end, I would say if a D65 neutral gray was virtually impossible to find, and then when found it was ten times the price, I would say no, pump the regular gas unless you have the extra money. When they are the same price and just as easy to get though, isn't it really a no brainer?

**mechman** · **10-18-07, 07:33 PM**

Quote:

wbassett wrote:

Grays again...

I see this come up over and over. Actually by now the real topic should be gray or white, and if gray what shade, not a constant debate about how to make them. That just seems counter-productive after awhile.

Amen!

Quote:

wbassett wrote:

Neutral references and tolerances were already mentioned so there is no need to rehash that again.

So what does that have to do with gasoline? Just an analogy...

If you pulled into a gas station and saw the price for both Regular and Premium were the same. We all know our car will run on regular, but the question is, if both were the same price, which one would you get? Now let's make this a little more interesting. The gas station down the street has Premium gasoline even cheaper. Now it's not a question of whether you'll pump the better grade gas or not, it's where you will get it.

It's still not as simple as that though. Say the cheaper gas price is at a station that for a personal reason you don't like. People boycott certain gas stations or stores all the time.

Now let's apply that analogy to our grays. Granted I don't know of anyone that boycotts a brand of paint, but some people do prefer one brand over another. As far as grays go, we know that unless the gray is some fancy hue meant for a pleasing decor look, it probably will work for a screen. Lots of things will work and I certainly am not saying they don't. The perception seems to be though that a D65 neutral gray is very difficult to get, and they are not. There are probably a dozen that have been identified right now, and more are on the way. These are not anything fancy or complicated at all, no mixing, no fuss. Just walk in and give the color code and name, and depending on the store, as little as $9 later you're walking out with a neutral base coat for your screen.

I continue to find it hard to believe that some people think they are difficult to get. I wonder why that is? Is someone feeding them that?

Quote:

wbassett wrote:

You could go look through the color swatches in the store and find a gray by a visual inspection, and yes it probably will work as a screen. The color balance and value though will be a complete unknown at that point, or we could say regular gasoline. My curiosity question though is if the same store sells one of the identified neutrals, and it costs the exact same price as the gray found by looking through the color swatches, what's the difference as far as just getting the one that was identified as a neutral? It certainly isn't any harder to get.

Many identified that fall within neutral. Maybe we need to identify our tolerances?

Quote:

wbassett wrote:

I understand there may be situations where a person only has one paint store available. That would be a rare situation, but is a possibility. If that is the case, then you have to go with what you have available. For those that only have a Home Depot in their area, the EF tints are one way to go, and soon there will be Munsell color matches done for Glidden and Behr paints. For those with only a Lowes nearby, no worries, they can call up anything and mix it. I live in the sticks and have a Lowes, two Home Depots, ACE, several Sherwin Williams stores, and three True Values within a 20 mile radius. When in doubt, check their store locator. You may have something available that you never realized.

D65 neutral isn't about paint, it's the industry standard that everyone uses... from filming a movie or television show, to post production, and all the way through to our DVDs, players, Televisions, and projectors. Why stop there then? If everything else is keyed to D65, then why not our screens? Especially when we have them readily available.

In the end, I would say if a D65 neutral gray was virtually impossible to find, and then when found it was ten times the price, I would say no, pump the regular gas unless you have the extra money. When they are the same price and just as easy to get though, isn't it really a no brainer?

Yes! That's not so hard is it folks! Maybe we should talk about it for another year or so.

I'm going to pm Smokey to respond here as he is our resident ISF expert, but my hunch would be that if you use something that pushes one or two colors hard - let's say green and blue - it would be difficult for a home user to use a DVE or an Avia dvd to calibrate on their own. But since most projectors are being manufactured using D65 as their tolerance, it would be easier if the screen was D65 as well.

mech

**<^..^>Smokey Joe** · **10-18-07, 10:24 PM**

Most projectors radiate in the general direction of D65. Scatter gun comes to mind.
The basic problem with calibration disks is that you are assuming that the DVD player is outputting reference standards, then they are ok, but then there is the cable debate, then comes the projector and finally the screen.

I didn't fix the issues I was having until I could isolate the projector and measure with a probe.

If you calibrate the projector to measure D65 from black to white and lets assume the primaries are reference aswell.

Q.So now what effect does the screen have? A. Depends

Q. On what?

These effects on light or radiation wave lengths.(lots of fantastic information here)
Pay attention to scattering, aborption, filtering propergation through mediums.

http://hyperphysics.phy-astr.gsu.edu...ligcon.html#c1

You get the idea, it is a messy business and one could argue why the DIY approach at times can be hit or miss. Basic problem is we can't repeat the structure of paint formation everytime.

The result will vary with the slight variations between DIY manufacture let alone everyone not having the same projector, set up exactly the same way and so on.

So for DIY The screen really needs to be broad spectrum neutral as possible. So that no matter what light source the balance remains the same.
You could argue you can make a D65 neutral screen. D65 as daylight or D65 as video?

So now broad spectrum may indeed not be what you actually want for video as the projectors actually are fairly narrow band output(DLP has fatter bands), so you could argue for a RGB absorption screen. AS pointed out with metallics and those screen shots prove the scattering is random. Not uniform so a RGB painted screen will tend towards non uniform appearance, thus a perfect calibration will be near impossible.

It is not impossible for DIY abilities to make a great screen. BUT it will be a very difficult road with the limited resources and time. Manufactures have more resources and time(man hours, staff) than you.

I still have some experiments to do myself, for fun of course. A continuation on my filtering screen idea. I have better tools now so I might redo my old experiment which partly looked at, out of RGB balance surfaces and calibration of them.

In the end you can tune a DIY screen, the results will vary with how well you can isolate each part of your video chain to address any issues you can before the screen itself.

In the end don't get too hung up on the screen, your video chain potentially has much worse issues.

I would actually argue that anyone who attemps DIY requires a measurement probe or have someone with one help you tune up the result.
Actually most side by side screen shots are basically rubbish because of error away from reference levels in the first place.

starting to ramble now....must get back to work....(boss)

**wbassett** · **10-18-07, 11:12 PM**

Quote:

mechman wrote:

Maybe we need to identify our tolerances?

I thought they were!

**wbassett** · **01-01-08, 04:39 AM**

I was recently asked if a scanner could be used to as a colorimeter or spectrophotometer to determine color balance of a sample.

The short answer is no.

Stanford University did do some experimenting with scanners and tried to use them as a very basic colorimeter but in the end they determined it could be done, but you'd have to basically gut the scanner, modify it extensively, and by the time you were done you probably could have saved some time, money, and heartache by just buying a basic colorimeter.

Can it be modified to match a spectrophotometer? No.

I spoke to Mark Fairchild about this. For those that haven't read some of my other threads, Mark is a regular contact I use for advanced questions pertaining color science, theory, and testing. Mark is the lead scientist and department head of the color and science theory branch of RIT (Rochester Institute of Technology, some impressive credentials). What Mark said was interesting.

First, he said yes you could use a scanner as a color space tool. I'm letting that sink in before the inevitable but... The 'but' is that it's not accurate or anywhere close to industry standards, not just the video industry, but anyone working in the color science field. Mark went on to say that yes a scanner could be used as a personal color space system, but only for that individual. Even two scanners of the same brand and model would not be able to produce reliable and more importantly reproducible results, meaning reproducible by anyone else, and there lay the major problem with this method. In order to discuss colors, we have to have a common reference point. That is what spectrophotometers do as well as individual 'anchor points' such as our always talked about and ever important D65 reference point. Without a reference, colors can't be discussed without any question of reliability. That is exactly why specifications and standards were developed.

Let's talk about this for a minute- A car company based in Japan wants to talk to the assembly line in America. They are sending a package with the color data and details for the newest line of cars and the colors they will be produced in, but the package hasn't arrived because mail, FedEx, UPS, or whatever delivery service- They all take time to process and travel. However the meeting needs to take place before the package shows up. By using a color space that both locations can understand and reproduce they can actually discuss the color line of the new cars and people on both continents will have an exact color match and know precisely what is being proposed. The textile industry also uses color spaces and tight specifications to do similar discussions coast to coast or continent to continent. The bottom line is they can discuss colors that are understood and reproducible on both ends of the conversation.

The same applies to the movie and television industry... without color standards the movie and television industry wouldn't be able to function. Nothing would be reproducible. So standards are needed.

So yes a scanner can be used, but only for a personal color space device. Mark went on to elaborate that it would be impossible to use this 'personal' color space to discuss colors tested with anyone else because of the inconsistency as well as the physical limitations of the hardware.

Yes, if you were to develop your own personal color space and only used the exact same setting, monitor calibration, and software, you could have your own personal color space. The key word though is 'personal'. As mentioned you would not however be able to discuss things with anyone else and have a any reference point let alone reproducible accuracy level. A perfect example of where this is a problem is say your consumer scanner dies. Your complete color space would then be rendered meaningless, even to yourself.

If it really was this simple, then Xrite, Hunter Labs, PocketSpec, as well as many other companies would be out of business as soon as this became public knowledge. I can speak about this from a personal perspective. When I first got involved with screens, I did just this... I tried using my scanner, PC, and PhotoShop to try to do basic color readings and I was immediately told the errors of my ways. I didn't get upset, I turned to the books and even went back to school for color science. The advice I was given was sound, not that I questioned it, I just didn't know at the time.

For anyone wondering about trying this, or if they've gotten information from someone that used a scanner as their source of readings- keep in mind you're talking to someone or using a personal color space and that is information that really can't be used to discuss color science, theory, or balance with people using equipment that meets industry standards and specifications.

One other thing to note is all those color cards people see in stores...

They are not the actual color, but a representation that approximates the color. The only way to determine the true color and balance is by use of a company Fandeck. What is a Fandeck? It is a color swatch of all the colors the company produces and is created from the actual source, not inks like store color cards typically are. For those painting their houses or a room inside their house, these color cards are 'close enough' and we have to understand that house paints aren't intended for exact and demanding specifications. If you want the exact color, you want a fandeck, and you will want a store to read your sample, color card, or Fandeck with a Colorimeter or Spectrophotometer. If you walk into a store and they put your sample material into a scanner... I personally would find another paint store.

I have been called a 'white coat' and accused of being a mad scientist when it comes to screens, paints, and my theories, as well as some of the things I have presented. At least I haven't been accused of not being thorough in my research! If people see me as a 'white coat' I take no offense at that. To me that's actually a badge of honor and I not only strive to maintain that level of tabloid integrity, but to actually live up to real specifications and standards.

I am not trying to resurrect the dead, or building the perfect being like Dr. Frankenstein, or having the wild eyed look of the gentleman to the right... but I do like to have standards where we can discuss things and know we're talking about the same thing from both sides.

So yes, standards are crucial and we at HTS are trying our best to stick to what the industry does and uses. It would be easy to make speculations or present something based on personal preference or initial evaluation. But that would also be irresponsible since we are honestly trying to wade through years of ideas and some misconceptions that continue to be presented as fact and without any actual proof.

**cynical2** · **01-01-08, 09:16 AM**

Well said, Bill. Many of us wish that we could use our scanners (because they're inexpensive and just about all of us own one) to accurately measure color. But, like most things in life, there are no shortcuts.

I think it may be worthwhile to mention a few of the "most common" prosumer grade color measurement devices, for those die-hard DIY'ers with enough personal interest/passion (as well as enough disposable income) that they'd be interested in having the ability to accurately measure color. The landscape of available devices is not something I'm overly familiar with (other than mech's setup)...but maybe when you and he have some "extra time" (is there such a thing?), that could be added.

**wbassett** · **07-19-08, 11:02 PM**

Periodically I update this thread when a topic pops up and seems to get a life of its own. I don't post these tid bits to put anyone down or create controversy. It's more like what Fox Mulder says, "The truth is out there." Hopefully some will find this thread educational and useful in explaining some of the often misunderstood things in DIY Screens.

It's not that anyone in particular wants to intentionally put out bad information, many times it's an educated guess on the whys and hows of the way things work. Not surprisingly many of the hard core dedicated DIYers are actually engineers as their real occupation, I am and many on this site are as well. Anyway, engineers have a basic need to understand things. DIY screens is no exception.

I firmly believe that to move DIY forward we need some standards, and the movie and video industry are a great place to start. They seem to know what they are doing and have adopted certain standards such as the D65 standard we discussed earlier.

Gain was really the first topic discussed, and it ties into this post. Gloss and sheen will make a surface more reflective, and the more a surface reflects the light that strikes it, the higher the gain will be. But when we talk about paints, what exactly is gloss and how is it achieved with paint? Also what is sheen?

Why is paint glossy and what makes it flat?
The ingredients of glossy and flat paints are essentially the same. The difference is that in glossy (high gloss) paints the ratio of pigments to resin is lower than in flat paints where you have considerably more pigments for the same amount of resin. When the paint dries some of the pigments at the surface break through the upper layer and diffuse the incident light. In some low gloss paints a very small concentration of light weight flatting agent is added so that it quickly rises to the top to break up the incident light.

Gloss Uniformity
Gloss is not uniform over the range of viewing angles. Sheen paints may appear to be quite flat when viewed directly on (that is at 90° to the surface), but may have quite a high luster when viewed along the surface. This may be quite significant when painting long rooms or corridors, particularly those which have a light source at one end.

The gloss of a paint is essentially an aesthetic attribute. The vast majority of paint binders are inherently somewhat glossy and uniform reduction of gloss requires the precise disturbance of the surface of the film, so as to diffuse the incident light on it. By this definition flat paints are always rougher than glossier paints, even though this roughness is on a very small scale.

Gloss vs. Sheen

Although gloss and sheen are often used interchangeably, it is important to understand the difference between the two terms. Gloss is measured on a scale of 0 (no gloss) to 100 (perfectly mirror-like). Gloss reflectance is typically measured by deflecting a single beam of light at a 60 degree angle off a surface. The light is deflected into a receptor, which gages the intensity of that light in gloss units. The higher the number of units, the shinier the surface. This method is useful for evaluating all but the lowest and highest gloss levels.

Sheen is used to describe the low angle gloss (85 degrees from the perpendicular or 5 degrees above the plane) of a surface. Variances in the sheen of a surface are most noticeable in low gloss coatings. This method is especially useful for measuring the transition between flat and eggshell.

Gloss is a property of reflected light, therefore it can influence the visual color of a surface when viewed from various angles (the dreaded color shifting as was stated earlier in this thread that occurs with higher gain screens). This is commonly seen where coatings tinted to the same color, but with different gloss levels, are applied side by side on the same substrate. Ideally, wall coatings should be used that have the same or a very similar gloss reflectance at both 60 degrees and 85 degrees.

Gloss levels vary widely among manufacturers
To establish standards for gloss reflectance, MPI conducted an intensive lab study of more than 100 samples of eight brands of premium paint. Five of those brands were produced by multinational paint manufacturers and three were produced by regional manufactures (small, medium and large). Information on the study, as well the tables and figures presented here, are available on the MPI web site at www.paintinfo.com.

This is the nature of gloss and paints and there is a noted problem with color changes depending on the viewing angle. When we translate that to our screens, it means that there is a viewing cone and 'sweet spot' and we are back to the whole gain conversation again.

This is why I am adamant when I say gloss and sheen are not the ultimate answer. Gloss is a cheap and quick fix for gain, but has some serious trade offs. Let me ask this before we move on, when is the last time anyone has seen a commercial screen that is glossy and glassy in appearance? Never, because it negatively affects the projected image and the goal is to reproduce the image and enhance it, not take away from the experience.

I was thinking about going into polys and how they interact with paints both as a top surface coating as well as when they are added to the paint itself, but that discussion is going on in another thread. I may add that here though since this is a thread that discusses various topics and myths and tries to make sense out of some of the senseless postings out there.

**wbassett** · **11-10-09, 12:14 PM**

It's time to blow the dust off this thread and bring it back to people's attention. Yes some of the information is technical. Yes it is all pretty dry reading, i.e. boring to 99.99% of the people out there. But it is legitimate information about topics I see some people talk about and state facts and theories and word things so they sound really really good to the new people that don't know anything about screens or color theory yet.

There always seems to be a topic that gets abused. By abused I mean it somehow becomes a buzz word or phrase and then someone keeps pushing it and promoting it until others start repeating the same nonsense as if it really is a fact. I do believe back in the day this very type of thing is why people were convinced the world was flat!

Well we know the world isn't flat, and now I'm sadly going to upset a few people by telling the DIY community a truth- A neutral gray is a neutral gray. It does not matter how it is made, if it is neutral it is neutral. Let me say that again, it doesn't matter how it is made!

Here's the theory- Some people came up with the idea that since projectors work by combining RGB light to create the image and colors, a screen made using Red, Green, and Blue pigments would be best to reflect the projector light back at the viewer. It sounds good. In fact it really sounds interesting... that is to anyone that doesn't understand colors.

I have even seen some people discuss how the RGB pigments work on a 'molecular level' to reflect the RGB light that the projector produces. Some of these discussions were even very in-depth, with charts and graphs and speculations...

Unfortunately it simply doesn't work that way.

When a color is made by combining two or more pigments, there is no 'molecular' light reflection going on, and if there is it is beyond what us humans can see. It is also beyond what our very precise equipment can 'see'! People should be more concerned with impurities in the paint and pigments than trying to come up with interesting but completely untrue theories that eventually get repeated as facts... just like the world being flat!

And folks this isn't just me saying this just to be controversial. This is just how it is and part of color science and how all of this works.

Quote:

Dr. Fairchild wrote:

No it does not matter how it was made if the spectral curves are the same. We would have no way to tell them apart. There might be a difference in the stability (e.g. lightfastness) of the pigments for different choices. If anything, the black and white combination would probably be better.

This is in reference to a discussion on this exact topic. Note the last thing he said in that statement, that a gray created using black and white would probably be better than a (my words here) 'complex' gray created using multiple pigments.

Quote:

Dr. Fairchild wrote:

There is more than one way to make a gray. This is due to "metamerism". Since our eyes have only three cone receptors, we see color, but not spectral curves. Therefore a gray can be made up of a variety of spectral curves (e.g. one might be perfectly flat across the spectrum and another might bounce up and down a bit but still integrate to gray). A neutral made out of white and black will have a fairly flat curve and look neutral under a variety of light sources. A neutral made out of colored pigments might have a more wavy curve shape and look neutral under some light sources and not others. Under a light source where they match, we have no way to tell them apart.

However a neutral with a nice flat curve shape will be more stable across changes in illumination.

So yes, there is more than one way to make a gray. In fact the RGB method is actually worse than a simple black and white method! To be fair, most people wouldn't see any difference, better or worse.

Which brings us back to another topic... complexity. This is also another thing I have said many many times. Just because something is more complex does not mean it is better, sometimes it is just more complex and complicated is all. Always though, the complex method will have more areas that can 'break'.

If there is no need to build something using 100 intricate parts when the same thing can be accomplished with one or two items, it is easy to see which one is more prone to having problems. This is exactly why using multiple pigments and mixing by eye with crude measuring tools simply will not yield a neutral gray, or at best it would be extremely difficult to do. Nor will it produce consistent and repeatable results. There are too many variables. All it takes is just one to be off by even a slight amount and now you don't have a neutral gray but a color. And a color is the last thing we want for a screen because that's where pushes come from.

Unfortunately as long as there are people, especially ones that don't know a particular topic and are relying on others to guide them... there will always be charlatans out there. Not everyone is a snake oil salesmen though, some actually believe their own pitches. Often this makes the task of trying to get the truth out there even more difficult since the barker really does think he is preaching about something real and revolutionary.

I wish there was some special and magical thing that separates screens from the rest of the world and the rules of colors and color science, but there really is no magic. Things work the way they do for a specific reason. Once we understand the whys and how's we can understand what we need to do to build a better screen.

**mechman** · **11-10-09, 02:47 PM**

I kind of always got a kick out of the 'ambient light rejecting paint research' which revolved around finding a paint that would reject (or absorb or whatever they were thinking) the ambient light spectrum. It made sense until you wondered what would happen to that particular spectrum if it was actually part of the film or show you were watching.

I mean that particular spectrum (of probably just about every bulb out there) is a part of everything we see daily. And then how would one account for the many varieties of bulbs? And their different forms of lighting - ie day light, cool, warm, etc.

There is no magic to any of this. It really is all common sense when you get right down to it.

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