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1C2,

Basically, all we're doing is comparing the two. The readings from the pj is what is hitting your screen. And the reading from the screen is what is reflected back. If there's a difference between the two, the screen is affecting the image. If it's a big difference, as I've seen with some things, it may be detrimental to the effect of not being a viable solution.

My initial look at the numbers shows me very little difference between the two readings. I see a very slight drop in blue, but nothing significant. Looks good so far! :T

Also, I disregard all of the readings below 30IRE. I'll have more for you later this evening when I have a bit more time to look at these files. :nerd:
 

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Basically, all we're doing is comparing the two. The readings from the pj is what is hitting your screen. And the reading from the screen is what is reflected back. If there's a difference between the two, the screen is affecting the image. If it's a big difference, as I've seen with some things, it may be detrimental to the effect of not being a viable solution.
This part makes sense. Using computer numbers, if I shoot a 255,128,0 and get back a 249,128,0 then the surface I am shooting on is "absorbing" 6 points of red and is thus not completely neutral.

My original question is more understanding the significance of the various graphs available in HCFR.

My initial look at the numbers shows me very little difference between the two readings. I see a very slight drop in blue, but nothing significant. Looks good so far! :T
Good example, in one of the graphs I did see a difference in the blue line from the two different sets of readings.

Also, I disregard all of the readings below 30IRE. I'll have more for you later this evening when I have a bit more time to look at these files. :nerd:
Good, cos I notice the numbers are all over the place at lower IRE. Is that that simply because the Spyder3 is not good at low IRE? I assume the super-spendy colorimeters do better at low light.

Slightly OT: Generally speaking, total neutrality is the ideal goal, but also exceedingly difficult to get perfect. So how big a deal is it? Is not the purpose of a calibration to correct for such differences? I understand a big push in one colour may be too big to correct for, but little ones should be no big deal. Could you actually have a screen surface that is a better overall performer in other respects but exhibits push in one colour. A good calibration can correct for the push, leaving you with a better screen than one that was perfectly neutral but less well performing in other respects?

I understand as screen formula developers that the holy grail is totally neutral, but is there a risk that goal is followed to the detriment of other goals? For example, on other forums it seems that gain or reflectivity is the goal, to the detriment of neutrality. I'm not claiming to understand the complexities of the art/science, just curious...
 

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I just look at the numbers in HCFR, not the graphs. Believe it or not, after a couple years of Bill pounding this stuff into my head, some of it actually stuck! :dumbcrazy: Let us know which graphs your curious about and we can help you out. :T

Is that that simply because the Spyder3 is not good at low IRE? I assume the super-spendy colorimeters do better at low light.
Yes. And as for the super spendy colorimeters, we may find out in the not so distant future. :T

Slightly OT: Generally speaking, total neutrality is the ideal goal, but also exceedingly difficult to get perfect. So how big a deal is it? Is not the purpose of a calibration to correct for such differences? I understand a big push in one colour may be too big to correct for, but little ones should be no big deal. Could you actually have a screen surface that is a better overall performer in other respects but exhibits push in one colour. A good calibration can correct for the push, leaving you with a better screen than one that was perfectly neutral but less well performing in other respects?
It is not that big of a deal when everything is close. However, when everything is not close and you're dealing with a projector that does not have a CMS, it's a big deal. Most of the pj's we're dealing with in the diy world are ones without a CMS. Even my BenQ W5000 doesn't have a real CMS. It's kind of a hybrid watered down CMS.

I understand as screen formula developers that the holy grail is totally neutral, but is there a risk that goal is followed to the detriment of other goals? For example, on other forums it seems that gain or reflectivity is the goal, to the detriment of neutrality. I'm not claiming to understand the complexities of the art/science, just curious...
Gain is so yesterday. lol It may be needed in certain cases, such as the house of worship thread, but rarely does any projector need a screen with gain. BW has a tad bit of gain - probably along the lines of a .15 or a .2 gain advantage over a matching neutral gray. That's not bad. The bad is the haphazard dumping of polyurethane and micas in a cauldron of screen goo and calling the result 'pop'. It's more like fizzle. Gain introduces a lot of issues. And those issues are usually coined as 'pop' from the maligned troller of customers (MississippiMan). If you know what I mean... ;) Check out the Silver Fire thread. Check out the readings there. That can tell what gain from heavy doses of mica and polyurethane will get you.

Is Maurice still over at avs? Do they even still have a diy screen forum?
 

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Discussion Starter #24
Slightly OT: Generally speaking, total neutrality is the ideal goal, but also exceedingly difficult to get perfect. So how big a deal is it? Is not the purpose of a calibration to correct for such differences? I understand a big push in one colour may be too big to correct for, but little ones should be no big deal. Could you actually have a screen surface that is a better overall performer in other respects but exhibits push in one colour. A good calibration can correct for the push, leaving you with a better screen than one that was perfectly neutral but less well performing in other respects?
I'll leave the calibration and colorimetry stuff to Mech and Bill, but I'll weigh in on this. A perfectly color neutral screen is very hard to get, as is a perfect anything in the real world; but luckily we don't need true perfection. Some time ago Bill and Dr. Mark D. Fairchild discussed the matter and came up with a set of neutrality standards for projection screens (which is what we currently use to determine levels of screen neutrality). Most projectors can compensate for small screen neutrality variances, but the more a PJ has to compensate the less chance it can do so properly and the greater chance it will throw other colors off at the same time; thus the desirability for as neutral a screen as possible. Also, the further a screen is from neutral the greater image colors will vary as the projected image drifts away from D65 (an effect called metamerism). Very few screens are perfectly neutral, very few PJ's are perfectly D65 - thus the need for calibration.

Yes, if you need a screen of a certain brightness and that brightness could not be attained with a neutral screen you would have no choice but to use a screen that would achieve that brightness even if it were less neutral. The thing is, screen neutrality (at least with a painted screen) isn't all that hard to achieve if it is approached from a scientific aspect.

The case above where someone hypothetically had to settle for using a non-neutral screen to achieve a viewable image is a case where the wrong projector was being used. Bill has said for quite some time that home theaters should be designed by determining what lighting conditions the screen will be viewed in (no ambient light or lots of it) and then go shopping for a PJ and screen. This makes so much sense! Unfortunately, most people either get whatever PJ is on sale, or buy one that a friend says works well, without taking their viewing conditions into consideration. That leaves them trying to find a screen that will compensate for using the wrong PJ. Many times this can be done, but has definite limitations. No screen can totally compensate for not having enough lumens to start with.

I understand as screen formula developers that the holy grail is totally neutral, but is there a risk that goal is followed to the detriment of other goals? For example, on other forums it seems that gain or reflectivity is the goal, to the detriment of neutrality. I'm not claiming to understand the complexities of the art/science, just curious...
I would say the simple answer is no. Neutrality doesn't affect gain. The color of a screen has nothing to do with it's reflective properties other than how much light it absorbs rather than reflects. The darker the screen, the less light it reflects.

Screen gain is a subject that is almost universally misunderstood. There is a general feeling that more gain is better no matter what. This is just the opposite of what it true. Think of screen gain as the ability of the screen to focus the reflected light toward the central viewer. To do this it needs to redirect light away from somewhere else to point it straight toward the audience. This means that those light rays are not being reflected to areas distant from the central area on-axis with the PJ. This makes for a darker image for those side seats. No screen generates light, it can only reflect what light it receives from the PJ. If a screen has too much gain it will also hotspot, which is when portions of the screen are visibly brighter than other areas of the screen which should be the same brightness.

We only need gain when the projector isn't bright enough for the job. In the past this had been the case more often than not, thus the need for screens with as high a gain as practical. With todays PJ's approaching the 10,000 lumen mark I personally think that the days of high gain screens are just about done.

The other mixes you are probably referring to were designed with gain as the primary goal and neutrality was deemed not to be all that important (and still doesn't seem to be). Back in the day they were designed PJ's had way fewer lumens than they do today.

The perfect screen is one that can't exist in reality. It would be totally black so it would absorb all ambient light hitting it yet it would still reflect 100% of the projected image to a wide audience.
 

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Wow! Detailed explanations guys. I warned you I was ignorant to the complexities of the issues at hand. I knew the gain crazy folks were off the mark, more because they didn't seem to care about other factors that would seem as important, if not more. As I said before, that's how I found my way over here from AVS.

I am certainly extremely happy with the results of my screen. I am guilty of buying a PJ without considering my room first, but also think I have ended up with an apporpriate PJ all the same since I have good light control and a powerful PJ (Epson 6500UB). Thankfully it also has a good CMS, so I have been able to tweak out any potential non-neutral quirks from HTS-X2, but the final verdict on that is now down to Mech. Whatever your results, I don't fele compelled to change anything as the screne more than meets my expectations. So unless you have some numbers that show me something is way out of wack, I'll consider myself done.

BTW, I forgot to mention, my PJ bulb only has 90 hours on it. As bulbs age, do they typically change their colour representation, or just get dimmer?

Thanks again. I am looking forward to Mech's assessment.
 

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Well my assessment hasn't changed much. ;) Mainly because I haven't had enough time to look at them. :hide:

The big thing I would try and work on, since you have a CMS, is getting the primaries and secondaries adjusted better. Specifically Red, Blue and Magenta. Try and get the dE to less than 10 - red is but you can probably get it a bit lower than 9. I wouldn't worry about anything else until you have more hours on the bulb. When you have more hours on the bulb I'd go back and adjust some things to get it closer to D65 and see if you can get the primaries/secondaries dE a little lower.

I will get a more thorough look at it sooner or later. :hide:
 

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So, can you give me some specific tips as to WHAT needs adjusting to correct the dE? I note that in HCFR there is no "real-time" dE value that shows in the list of values that show when you run the continuous measures mode I used to adjust things in the CMS. delta E only shows up after running a set of measures.

The calibration guide I followed is
here

It uses the 75% saturation windows in the AVSHD disk in combination with a spreadsheet and some target values to adjust the RGBCMY values towards. As I've already said, I am far from an expert so I just followed the guide as strictly as I could.
 

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What kind of things can you adjust in the CMS? On my BenQ I can enter a measured value for primaries/secondaries and then a desired value. That's how I get them to be what they should be. Do you have something similar.

We'll get it all figured out. :T In the mean time I'll go read that thread you pointed me to. Take a look at Tom Huffman's guide in the display calibration forum there as well. Kal has a very good guide here as well.
 

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The CMS is pretty flexible but maybe not so usable. The BenQ model sounds better.
I stole this quote from a review that describes is succinctly:
For those who are more technically inclined and like to experiment with all the subtle nuances of their image, the 6500UB will serve you well by accessing the Advanced section of the Image menu. It’s here you can adjust your Gamma from five settings ranging from 2.0 to 2.4. There’s also an RGB option that lets you adjust Gain and Offset for your red, green, and blue. And taking image customization to a whole other level, you’ll also find a section for RGBCMY which allows you to individually adjust the Hue, Saturation, and Brightness for red, green, blue, cyan, magenta, and yellow.
 

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Discussion Starter #31
Harp, I tried PMing you but your box is full...
Did you get the sample painted card I mailed you?
Sorry about that, I have an embarrassing tendency to let my inbox get full. :blush:

Yes, I got your sample and it looks great! Below is the Spectral Reflectance Chart for it. The bump in the deep violet and orange, and the dip in the extreme red end of the spectrum are indicative of a very neutral mix. We still don't know why neutrals have this curve. :dontknow:

The L* value equates to a N value of 7.84, which is a tad under the 8.0 value of a true N8, but only the most discerning eye could tell the difference even in side-by-side testing. The a* and b* values are both well under 1.0 and the fact that they are opposites (one negative and the other positive) is also very good.

The color temperature of this mix is 6487°K which is only 16° off from the D65 standard of 6503°K.

Well done! :clap:

 

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1c2,

Remember that I am an amateur at this. I have no training and only go by what others have taught me or what I have read. :T

For gray scale tracking I would adjust both the blue gain and offset up a notch while adjusting the red gain and offset down a notch. Ideally what you would want to do is adjust your offsets real time while displaying a 30 or 20IRE window and your gains while displaying a 80IRE window. Generally if you get those two in line the rest fall right into place.

The luminance for each of the primaries and secondaries is also low. Generally anywhere from .5-1. The ones I would be concerned with though would be red, magenta and blue. Those dE's are well above ten and I would try to get them lower. They also fall outside of the triangle which generally means they are over saturated - the y value being low on red/blue and high on green.

These are the numbers you should be shooting for:
x y Y
R 0.6400 0.3300 3.5094 (0.2126)
G 0.3000 0.6000 11.806 (0.7152)
B 0.1500 0.0600 1.1918 (0.0722)
Y 0.4193 0.5053 13.315 (0.9311)
C 0.2246 0.3287 12.998 (0.7905)
M 0.3209 0.1542 4.7012 (.2848)
W 0.3127 0.3290 16.507 (1.0)

Try and get the dE as low as possible. I'd shoot for less than 5.
 

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Sorry about that, I have an embarrassing tendency to let my inbox get full. :blush:

Yes, I got your sample and it looks great! Below is the Spectral Reflectance Chart for it. The bump in the deep violet and orange, and the dip in the extreme red end of the spectrum are indicative of a very neutral mix. We still don't know why neutrals have this curve. :dontknow:

The L* value equates to a N value of 7.84, which is a tad under the 8.0 value of a true N8, but only the most discerning eye could tell the difference even in side-by-side testing. The a* and b* values are both well under 1.0 and the fact that they are opposites (one negative and the other positive) is also very good.

The color temperature of this mix is 6487°K which is only 16° off from the D65 standard of 6503°K.

Well done! :clap:

Well, I think the "well done" needs to go to you, since you provided the formula, I just followed the steps...

The colour temp is only ~0.25% off, I'd say that's a pretty small margin considering how simple the formula is (three ingredients). So if the goal is simplicity with consistent results, that's very impressive!

The N value as well is a pretty small margin (2%), so all things considered an impressive result (and a lower N is probably okay for me anyway since I have good light control and a powerful PJ lumens-wise).

Not sure if I told you, but the sample card was rolled at the same time as the screen. I did coat 1 on the screen, then rolled the card. Waited. Then coat 2 on the screen, rolled the card. Waited. Then coat 3 and rolled the card. So its pretty representative of what went up on my wall. The only diff is the card was not primed with Kilz2, but it was a white card from a frozen food box. Given I put three coats on, I'd guess the primer (or lack thereof) would make a minimal difference.

As I've said before, I am exceedingly happy with the results, but its nice to have some science to back-up my satisfaction.

As per Mech's post, I have a little more calibration work to do - which I'll hopefully get to this weekend - its just nice to know I am calibrating against something that's pretty much ideal for my needs.

Thanks again guys!
 

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The only diff is the card was not primed with Kilz2, but it was a white card from a frozen food box. Given I put three coats on, I'd guess the primer (or lack thereof) would make a minimal difference.
After three coats the primer is having no effect upon the image. ;) Very little light gets through even two coats of paint. And what little does get through, virtually none of it would make it's way back.
 

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Discussion Starter #35
The colour temp is only ~0.25% off, I'd say that's a pretty small margin considering how simple the formula is (three ingredients). So if the goal is simplicity with consistent results, that's very impressive!

The N value as well is a pretty small margin (2%), so all things considered an impressive result (and a lower N is probably okay for me anyway since I have good light control and a powerful PJ lumens-wise).
I believe I mentioned this before, but the reason we design to such exacting neutrality tolerances is to allow for some error either from the user or the paint store. It isn't uncommon to have some variation due to mistinting when using tinted house paints, although this seems to be getting less as tinting systems improve their consistency.

We also try to make our mixes as easy to assemble as possible with little, or no, actual paint measurement; just pour the paints required into a bucket and stir. This lesson was learned from building the mixes posted on another forum where some ingredients had to be measured down to the milliliter or less. Many people have problems doing this, especially with some of the thicker artist paints used to color mixes. Such colors are concentrated and even a small error will make a difference in the final color of the screen.

In the mix family that HTS-X2 will be a part of the range of gray shades will be determined by how much neutral gray paint is added to regular C&S. In theory this would be an "infinitely adjustable" mix with any value from C&S alone (N9) down to where the gray paint comprises too much of the mix and the reflective properties of C&S are visibly diminished. In the real world this infinite adjustability is more about marketing hype than truly useful. Through testing and observation we have determined that there isn't much sense in having mixes closer together than N0.5 which is a "half-N" step.

Not sure if I told you, but the sample card was rolled at the same time as the screen. I did coat 1 on the screen, then rolled the card. Waited. Then coat 2 on the screen, rolled the card. Waited. Then coat 3 and rolled the card. So its pretty representative of what went up on my wall. The only diff is the card was not primed with Kilz2, but it was a white card from a frozen food box. Given I put three coats on, I'd guess the primer (or lack thereof) would make a minimal difference.
I forgot to comment on this before, but if your screen surface is the same as the sample card you would have gained little, or nothing, by spraying instead of rolling! That sample is the smoothest rolled sample I have ever seen. :T

As I've said before, I am exceedingly happy with the results, but its nice to have some science to back-up my satisfaction.
Yeah, I have no idea why some people are against scientific measurement of DIY screen mixes, unless perhaps the results would disprove their comments on screen performance - but I won't go there. :devil:
 

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In the mix family that HTS-X2 will be a part of the range of gray shades will be determined by how much neutral gray paint is added to regular C&S. In theory this would be an "infinitely adjustable" mix with any value from C&S alone (N9) down to where the gray paint comprises too much of the mix and the reflective properties of C&S are visibly diminished. In the real world this infinite adjustability is more about marketing hype than truly useful. Through testing and observation we have determined that there isn't much sense in having mixes closer together than N0.5 which is a "half-N" step.
Well I certainly think the idea is a great one. It was very easy to mix - the addition of the N6 to darken an already tried and tested formula is a bit of a stroke of genius if you ask me.
Theoretical question: how would BW compare to C&S plus enough N6 to be as dark as BW? Could it be better, or is it expected to be worse?
Next theoretical question: could a "lightener" be added to BW to achieve similar results?
Last question: Would this formula replace Scorpion? Its certainly easier to make (which is why I got here), it seems neutral enough, but is Scorpion "better"?

I forgot to comment on this before, but if your screen surface is the same as the sample card you would have gained little, or nothing, by spraying instead of rolling! That sample is the smoothest rolled sample I have ever seen. :T
Well thank you :) The only trick I can share is that I am pretty . I have done a fair amount of rolling for house decorating, so I have a bit of experience, but this was still a slightly new challenge, but probably only because I was more obsessive about it.

In the end I didn't really do anything different than when rolling a regular wall, other than probably go a little slower and be conscious about applying even pressure to the roller, etc... I followed the Tiddler technique, but then that wasn't too far from how I roll a wall anyway (other than doing the old W trick first). When I look at my screen up close, I cannot see any obvious lap marks or inconsistencies which is the thing I was most fearful of. I will say that the third coat probably helped with this so I feel its worth doing a third coat if you are rolling.

Hoping to do a second round of calibration today, but then I just bought an Xbox 360 for the HT room, so we'll see what wins... ;)
 

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Discussion Starter #37
Well I certainly think the idea is a great one. It was very easy to mix - the addition of the N6 to darken an already tried and tested formula is a bit of a stroke of genius if you ask me.
Thank you. The concept is based on Scorpion™ being two neutral screen mixes added together. A neutral plus a neutral equals a neutral. My experience with CSMS is that as the mix gets darker the reflective flakes become more apparent so the concentration should be lessened, thus the N6 paint does two jobs, it darkens the mix and it dilutes the CSMS so the mix isn't too reflective for the shade.

Theoretical question: how would BW compare to C&S plus enough N6 to be as dark as BW? Could it be better, or is it expected to be worse?

Next theoretical question: could a "lightener" be added to BW to achieve similar results?

Last question: Would this formula replace Scorpion? Its certainly easier to make (which is why I got here), it seems neutral enough, but is Scorpion "better"?
These are excellent questions and more comparative testing will need to be done to truly answer the first one. I would expect that C&S™ darkened to the shade of BW™ would offer similar performance characteristics, but only testing will determine that. At the N7.5 shade the darkened C&S™ would have a bit higher concentration of reflective flakes in it, but the aluminum in BW™ is probably the better reflector.

As for lightening BW™, it was found that white paint could be added to lighten the mix to N8 without affecting the reflective properties too much, but that was the limit. I believe the ratio for that mix is 4:1:1 Bermuda Beige/AAA-F/White.

I like the idea of the Scorpion™ mix since it is based on two proven mixes simply added together. Again, testing has to be done to determine if HTS-X2 performs as well as Scorpion™, but my gut feeling is that it won't. However; that is why we test - to actually know and not just guess.

Well thank you :) The only trick I can share is that I am pretty . I have done a fair amount of rolling for house decorating, so I have a bit of experience, but this was still a slightly new challenge, but probably only because I was more obsessive about it.
I have to assume that there is a word missing after "pretty", my guess is that for some reason it didn't make it through the "naughty filter" used here at HTS. Either that or brushing your teeth and combing your hair really does help roll a smooth screen. :rofl:

Hoping to do a second round of calibration today, but then I just bought an Xbox 360 for the HT room, so we'll see what wins... ;)
Lets see... calibrate a PJ or play with an Xbox... wow, that is such a hard decision. NOT! :rofl2:
 

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A-N-A-L

Made for a funny sentence when it dropped the word though...
I think simply saying you are a perfectionist would have served better because I just looked up the word and phrase and it only supported my opinion that Psychoanalysis is for the birds... the missing word was funny though! :D
 

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Harpmaker - Thank you for your creative formula!

1canuck2 - Thank you for all hard work to prepare a screen using this new mix.

Question to Harpmaker - Do you have any plan for N9 or N8.5 mix? Also I would like to use Valsper paint...do you mind giving your HTS-X2(N8) formula for Valsper paint Or should I just bring your Behr formula and Lowes staff should be able to match the colors?

I am new member to this forum and very much inspired by your HTS-X2(N8) formula, its result and its simplicity. I would like to prepare DIY screen based on your formula but looking for N9 or N8.5 mix. My PJ is Mitsubishi HC3800 and I am not sure if N8 is too dark for it or not. My PJ is in basement and I am covering all my window to block all ambient light. Right now I am projecting on white wall but wanted to try out something different and better using your formula.

Appreciate your time and efforts. Keep up the good work!!!

Thanks again!

K.
 
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