The Contrast between Contrasting Screens' Contrast - Page 4 - AVS Forum
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post #91 of 162 Old 05-18-2007, 09:21 AM
 
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Quote:
Originally Posted by Tgreenwood View Post

An "ordinary" screen is a screen that reflects back all light that hits it equally.

Tgreenwood

So it's white then!

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post #92 of 162 Old 05-18-2007, 10:10 AM
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Quote:
Originally Posted by MississippiMan View Post

A "simple gray" matching the shade of the current SF sample will also be included in the upcoming further comparisons to assist in proving or disproving that point. specifically, both Gray samples will go head to head. One will Burn up the Post, the other will get shot down in Flames. Or both might just simmer together on the same Stove Top. Either way, it will certainly be interesting eh?

I'm glad to hear a comparison is in the works. The little test I did last night took a total of 30 minutes and that included uploading the pictures and writing the recap.

So if an example of BF is available it shouldn't take long to do a comparison to other things.

I would hope as you have mentioned many times the BF has both a brighter image a higher perceived contrast image and a wider viewing cone than a simpler gray screen. So as long as the test screen shots contain a split image between at least two samples within the same picture and then shots taken both from the center and also off axis, it will finally be clear to everyone that the metallic BF screen paint is performing under a degree of increased efficiency over a simpler gray of the same shading of gray. It will also be clear to see to what amount the improvement lies.

Any idea when we might see this comparison?


Bud

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post #93 of 162 Old 05-18-2007, 10:47 AM
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Quote:
Originally Posted by prof55 View Post

Great comparison, Bud. I think it goes a long way toward showing that viewing environment is just as important to satisfaction as raw numbers. But being a technical nut, I still like to see raw numbers improved as much as possible before the subjective element is added!

Garry


Well that's why I tried to add a few number to the two comparison photo posts just for the math minded.

Any comment on the method I used to approximate the difference in black and white contrast ratio using measured RGB color values? Given the same image source within a photo and the three different screen surfaces can we make a determination on your question?

The issue as to if a screen can improve CR above what the projector is capable of doing I'm guessing can be labeled Busted. But what about ambient light diminished CR? Or should we call it real world CR?

Do lumens play a bigger part in it than some would think?


The funny thing is I went to the $3000 and up projector forum the other day for the very first time. I could hardly believe I had never looked around in there. But guess what one of the big topics of discussion surrounding the big $$$ 1080p high CR projectors is?


Bud

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post #94 of 162 Old 05-18-2007, 11:30 AM
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Quote:
Originally Posted by bud16415 View Post

Any comment on the method I used to approximate the difference in black and white contrast ratio using measured RGB color values? Given the same image source within a photo and the three different screen surfaces can we make a determination on your question?

I think the method is valid, within reason... There's almost always going to be totally black and totally white portions in any screenshot taken in ambient light with the camera on auto, so I'm not sure that part of the comparison matters. But measurements within the screen should be reasonably accurate.

Here's another way to remove some of the "subjective" factor - remove all color from the image:



Reminds of the days of black & white TV. If it was 1965 and this was a normal TV, I'd be reaching for the contrast knob. Even in the context of the surrounding dark and light references, it looks washed out.

So just for fun, I tweaked my imaginary black & white TV:



Much better!

Garry
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post #95 of 162 Old 05-18-2007, 11:41 AM
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Here's another set of pictures where TV is black & white, but the world is color:



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post #96 of 162 Old 05-18-2007, 12:34 PM
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Quote:
Originally Posted by prof55 View Post

I think the method is valid, within reason... There's almost always going to be totally black and totally white portions in any screenshot taken in ambient light with the camera on auto, so I'm not sure that part of the comparison matters. But measurements within the screen should be reasonably accurate.


My point was in checking around the room for indicators of pure black and white in the second set of pictures was to kind of show there was no issue with the cam not capturing the full realm of colors between black and white. I know MM has posted many times asking that some objects outside the image be included with the image to lend a feel or idea of the room lighting level especially when ambient light or CR is what is being shown. So in the case of these screen shots verifying what is outside the screen to be somewhat exposed correctly leads me then to saying what is inside the image is true to what our eyes would have seen if we were sitting in the bar.

Once again it's a nice bright image that is easily watched I'm sure but without some dark content it's difficult to say it's an ambient light beater. Or even if it has superior CR maintaining abilities. (By the way in my mind those last two statements are one in the same.)

One of the hardest things in the world to do in taking a screen shot of something you feel has good ambient light properties and or CR maintaining properties IMO is to take a photo of a dark image or a image with a fair amount of dark subject in a well lit setting. Because in doing so even a truly remarkable image given the conditions just comes off looking like I wouldn't watch that.

I have posted a series of shots before where I tried to capture a so so CR image in 4 different lighting settings. And with all the black work I have done around my screen its hard to tell the light level is bright where I'm sitting. That's why I held something up in the foreground of the shot to give a feel for the level over my seats. That's really the ideal setup for a sports viewing setup staged lighting getting brighter as it goes away from the screen.

Here is one such screen shot. Very bright at the seats 12' from the screen.



Same picture lights out.



It's easy to see what is lost with the lights up that bright and I normally go about half way between these two settings for sports with the guys.

But I stop short of saying the screen is ambient light friendly even though it is to some extent. But the room paint and lighting placement are equally responsible.


Bud

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post #97 of 162 Old 05-18-2007, 05:26 PM
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Quote:
Originally Posted by bud16415 View Post

Any comment on the method I used to approximate the difference in black and white contrast ratio using measured RGB color values?

Just to make sure we were getting comparable results, I did the eyedropper thing on the lights out white, black and gray screen test image that you posted.

Because of the method we are using here, I also came up with something I call RGB Contrast Ratio, RGB CR for short.

From Bud's numbers
Lights out screens:
White screen W 246 - B 30 = 216 range; W 246 / B 30 = 8.2 RGB CR
Black screen W 105 - B 2 = 103 range; W 105 / B 2 = 52.5 RGB CR
Gray screen W 234 - B 17 = 217 range; W 234 / B 17 = 13.76 RGB CR

What I got
Lights out screens:
White screen W 244 - B 25.6 = 218.4 range ; W 244 / B 25.6 = 9.5 RGB CR
Black Screen W 99.3 - B 1.6 = 97.7 range ; W 99.3 / B 1.6 = 62 RGB CR
Gray Screen W 232.3 - B 24.3 = 208 range; W 232.3 / B 24.3 = 9.55 RGB CR

Sorta close, but not as close as I thought it would be. The range and the RGB CR are a lot closer between the white screen and the gray screen in my numbers.

Then I went back to the first post and sampled the brightest white and the darkest black in the sports bar screen that has the three sportscasters in it. Here's what I got.

Moderate ambient light "Comparing Bonds and T.O." sports bar image:
W 249 244 247 (papers in front of center guy)
B 42 42 38 (crook of arm of center guy)

W 249 244 247 avg 246
B 42 42 38 avg 41
W 246 - B 41 = 205 range
W 246 / B 41 = 6 RGB CR


Then I used Bud's numbers on the high ambient lit screens and did the RGB CR calculation with them.

Ambient lit screens:
White screen W 242 - B 102 = range 140; W 242 / B 102 = 2.4 RGB CR
Black screen W 78 - B 13 = range 65; W 78 / B 13 = 6 RGB CR
Gray screen W 227 - B 102 = range 125; W 227 / B 102 = 2.2 RGB CR


Looking at the screenshots and the numbers, here are my thoughts.

Using this RGB Method:
The Silver Fire screen maintains contrast ratio in moderate ambient light almost as well as the white or gray screens do in lights out conditions, and definitely does much better than the white or the gray in high ambient light conditions. (How much difference in ambient light there is between Bud's room and the sports bar I don't know, but from the look of the background it looks comparable. It would be good to test in identical conditions.)

While the black screen has the best RGB contrast ratio, the range (gray scale?) is small compared to the other screens, and is not acceptable for viewing. It just plain looks ugly.
I think that the range from light to dark is a much better measure of "perceived" contrast, and how happy we are with our screens. It looks like a good standard to use would be the "range" number. The higher the range, the better the image on the screen looks.

To recap, using Bud's numbers from his test:
Lights out screens:
White screen 216 range
Black screen 103 range
Gray screen 217 range
Ambient lit screens:
White screen 140 range
Black screen 65 range
Gray screen 125 range
Ambient lit Silver fire screen: (my numbers)
Silver Fire 205 range

What do you guys think?

By the way, Bud, great idea. Extremely useful.

(Can someone do a "black and white" of the three sportscaster shot?)

Tgreenwood
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post #98 of 162 Old 05-18-2007, 06:17 PM
 
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Quote:
Originally Posted by prof55 View Post

I think the method is valid, within reason... There's almost always going to be totally black and totally white portions in any screenshot taken in ambient light with the camera on auto, so I'm not sure that part of the comparison matters. But measurements within the screen should be reasonably accurate.

Here's another way to remove some of the "subjective" factor - remove all color from the image:



Reminds of the days of black & white TV. If it was 1965 and this was a normal TV, I'd be reaching for the contrast knob. Even in the context of the surrounding dark and light references, it looks washed out.

So just for fun, I tweaked my imaginary black & white TV:



Much better!

Garry

Now that's interesting prof55!

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post #99 of 162 Old 05-19-2007, 03:33 AM - Thread Starter
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Below are a few pics of different content.

PJ is a DLA-HD1
DVD is 1080p Toshiba HD-DVD
Screen is 110" White Light Fusion
(MMud on Screen did contain a extremely small percentage of Red Oxide.)

A serious look at an Ambient comparison.





Close up.



Closer still.




The same image in the Dark.




Now closer in.





The largest Zoom-in of the Wraith King shows how extreme the difference is in ambient light, which in this case is EXTREME AMBIENT. Such a comparison of course favors the Silver Fire sample, but the real observation to be made is how extremely well the level of Black returns to the void in the King's mask/mouth, how much detail is restored (...or made more obvious...) and how much corrective action is observed that restores something much closer to true colors instead of the incandesent yellow light infused on the White MMud-LF surface.

On the other hand, in these shots there does not appear to be as significant an increase in the perceived level of Black "in the mouth" of the Wraith King in the shots taken in the Dark Room setting. I feel that this is explained mostly by the PJ's own capabilities, combined with program content. But in the areas involved with the SF sample that are lighter in hues, the difference is most assuredly there to observe.

Today I spray the Neutral Gray and Silver Screen samples. Just to be a little crazy about it, I'll do one each on both a Acrylic Mirror, and on pre-coated White Boards ( Cut from a Thrifty White panel found @ Home Depot ) This will also allow for a judgement as to if Light Fusion adds or subtracts to the properties that either of the more standard Mixes have to offer.

OH....BTW. Just today I saw a Road Island Red Rooster sitting on top of my Good 'Ol Boy Neighbor's Barn roof (approx 40' up) Now how he managed to get there, who can say, but it just might be an omen.

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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post #100 of 162 Old 05-19-2007, 05:35 AM
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What you think you've gained with ambient light, just gets lost with lights off. Look at how dingy the whites are in the SF mixes with lights on or off. Blacks are just as deep with lights off. Hmmm? So what does that do to contrast? Perceived or measured?

Also, colours look so much more natural with the white/red oxide screen. IMO, it really is no contest what looks better to my eyes.

It seems to me that from my tests, whether white or dark gray, on/off contrast is the same. Can I say that ANSI contrast is better on a white screen? From my initial test...yes. I will need to perform further testing, which will take awhile because I have limited time at night now.

Your test above just proves to me, that a white screen/light gray screen is the way to go. This is something I have been trying to advocate since the advent of CGIII. bud also showed that in his pictures. His lightish gray screen looks really good. I used to be a dark gray guy, but not anymore. I have seen the light.

Two things...

1. Take an off axis, say 45 degrees, picture of the same shot
2. Put your money where your mouth is and send me a sample of SF and I will test it

Meow.
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post #101 of 162 Old 05-19-2007, 08:14 AM - Thread Starter
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Quote:
Originally Posted by benven View Post

What you think you've gained with ambient light, just gets lost with lights off. Look at how dingy the whites are in the SF mixes with lights on or off. Blacks are just as deep with lights off. Hmmm? So what does that do to contrast? Perceived or measured?

What you say looks dingy is not. What you think is bright White is actually an excess of light. Hot Spotting? I would not go so far as say that, but I can say two things with certainty.

As you and others have pointed out in the past, a digital camera is not as an exacting reference tool as we'd like to have. I've found that as actual PJ Lumen levels have increased, along with resolution and contrast, the performance traits of many screens have changed due to such. It's just still getting things matched up correctly, but that cannot always be done. As in this case, be it the Demo panel (conveniently at hand), the existing screen (more on that*), or the change in PJ specs, all were simply "at hand" not put together to represent "a perfect test".

Quote:


Also, colours look so much more natural with the white/red oxide screen. IMO, it really is no contest what looks better to my eyes.

That's you right to think and say so, however you seem to overlook that I just had to know the disparity existed between the very dark Demo I used and the Light Fusion. And the quality of the PJ? It's not like I tried to put on "Airs" or tip the scales completely in my favor. Nor did I fail to point out the small difference I noted between the Cr in the last shots in the dark. But I chose that material once again to show primarily only the CR values that come from seeing something in a monotone range. Bright Colors always are an advantage, and I sought no such help on this last round of images.

Someone with something more to say than a predisposed bent to criticize might observe how little the variance in natural color is for such a dark hue matched against a good white. The PJ was "Out of the Box" which is fine for the HD1 anyway, but certainly it was not calibrated for the dark Silver Fire by any stretch of your imagination. But that would take some effort on your part to take that much effort to be willing to read into whats happening here any more than what you want to.

Quote:


It seems to me that from my tests, whether white or dark gray, on/off contrast is the same. Can I say that ANSI contrast is better on a white screen? From my initial test...yes. I will need to perform further testing, which will take awhile because I have limited time at night now.

Under any really dark conditions, and with a good PJ with corresponding Cr specs, Contrast should appear to be greater than any Gray. That only makes sense. Cry eye, Benven. Are you telling us something new, or just posturing? But with any ambient light present, be it a poor choice of wall paint, a white ceiling or light colored carpet, a poorly directed Can light, everyone wearing a white suit......, or if it is the PJ's light reflected back at the screen from one of those surfaces, the White will not suffice. Picture quality will suffer. How to avoid that and what means is best is the issue. That's being done not with eye candy primping, but with something just a little bit removed from a Gray Scale Color Pattern.

Just remember that not everyone will be able to "Blacken" or "Black Out" their room. Every room is not a dedicated Theater. You and others know I see a very many different aspects of "Home Theater" and they are not all dedicated by anything approaching a 25% to 75% ratio of dedicated to "Family Room".

So forgive me if my current interest is not on making a great "White" screen. I did that long ago. I'm doing something different, so if that is not where you are, why are you here?

Quote:


Your test above just proves to me, that a white screen/light gray screen is the way to go. This is something I have been trying to advocate since the advent of CGIII. bud also showed that in his pictures. His lightish gray screen looks really good. I used to be a dark gray guy, but not anymore. I have seen the light.

Yeah. Through Blinders.

I'll be presenting lighter versions of Silver Fire soon. They will easily exceed your simple "White / Gray in Dark & Light Room" performance criteria AND provide greatly improved Ambient Light performance, while offering nothing that can even remotely be construed as a confined viewing cone.

Quote:


Two things...

1. Take an off axis, say 45 degrees, picture of the same shot
2. Put your money where your mouth is and send me a sample of SF and I will test it

1. It's coming
2. Who are you to ask of such in such a manner and expect anything.

Given that you refused some time ago to let others ask the same of you, you should not ask such of others. You yourself have as easy access to the SF ingredients as any others do in CAN, so you could have gotten that taken care of long ago. You might have had real fodder for criticism then, or perhaps not, but if you really wanted to know for anything like a "right" reason, you'd have gone there. YOU chose not to for whatever reasons. And you make demands just to create a bad atmosphere where none is needed or wanted. I'm not paying anything toward your enlightenment. I have others who have asked for such and they concern me more. I have enough issues keeping such commitments to those who matter that doing such for your type of request is not going to happen.

Ahem...........

As this Comparison progresses, and varying screens are used along with the samples being shunted around, the title will be well justified. Dark Hued SF screens. Light Hued SF screen Painted Wall. Painted Mirrors. Different PJs, from 1k to 5k jobbies and their resulting variables. And at least there will be enough different samples to satisfy 'most' anyone.

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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post #102 of 162 Old 05-19-2007, 08:49 AM
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Well, you guys are doing a good job wearing me down. Reading this thread is akin to stepping through a mine field, except the mines keep going off all over the place.
Well, at least all seem to be working towards a common goal.

Yeah, I've said enough. Perhaps it's just time to seek out a more harmonius read.
Good luck, and someone PM me when some common ground is reached. Thanks.
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post #103 of 162 Old 05-19-2007, 03:56 PM
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Quote:
Originally Posted by MississippiMan View Post

OH....BTW. Just today I saw a Road Island Red Rooster sitting on top of my Good 'Ol Boy Neighbor's Barn roof (approx 40' up) Now how he managed to get there, who can say, but it just might be an omen.


MM

I read your post this morning and all day I have been thinking about the question you asked.

I haven't a clue how that Rooster got there. It must be close to 1500 miles from Road Island to Mississippi.

That's one heck of a long walk for a bird. All I can figure is there must be some pretty good-looking chics down your way.


Bud

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post #104 of 162 Old 05-19-2007, 04:01 PM
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Quote:
Originally Posted by CMRA View Post

Reading this thread is akin to stepping through a mine field, except the mines keep going off all over the place.


CMRA

Good analogy but a closer one might be walking thru a cow pasture bare footed.


Bud

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post #105 of 162 Old 05-19-2007, 06:47 PM - Thread Starter
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Quote:
Originally Posted by bud16415 View Post

MM

I read your post this morning and all day I have been thinking about the question you asked.

I haven't a clue how that Rooster got there. It must be close to 1500 miles from Road Island to Mississippi.

That's one heck of a long walk for a bird. All I can figure is there must be some pretty good-looking chics down your way.

Yessir......buts deys 'most all ar's Sisdurs n' Cuzins.

Curse dat n'ver stopeded a hole lotta many yarbouts aforen iffn days was inna pinch.

Akshuly, that naybor has at least 4 difernt types of Hens and 3 difernt Roosters. 'Bout 40+ Cluck'rs in all.

And he's the Poppa of the 98" SFLF screen shown in the "Silver Fire Lights Up Byhalia" thread. Take a re-vist to da nayboorhud 'n catch the "E"vanced 'Lectronics and "E" gellygant 'dee-coor' 'round the screen, and yer shur ta no how's come he owns sew meny "Shikkins"*

(*...that is how the "Boys" per-nownce it....)


Sum dose birds ar pretty dumb clucks 'n dat merminds me, I went 'n took de SIDE shots dat wer aquested of me earlier on dis thread. Ana few more tu boot. Dey ar cummin' reel sewn. I'll scatter 'em about and see what comes a'scratchin' 'n a peckin'

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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post #106 of 162 Old 05-19-2007, 11:13 PM
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Quote:
Originally Posted by Tgreenwood View Post

Just to make sure we were getting comparable results, I did the eyedropper thing on the lights out white, black and gray screen test image that you posted.

Because of the method we are using here, I also came up with something I call RGB Contrast Ratio, RGB CR for short.

From Bud's numbers
Lights out screens:
White screen W 246 - B 30 = 216 range; W 246 / B 30 = 8.2 RGB CR
Black screen W 105 - B 2 = 103 range; W 105 / B 2 = 52.5 RGB CR
Gray screen W 234 - B 17 = 217 range; W 234 / B 17 = 13.76 RGB CR

What I got
Lights out screens:
White screen W 244 - B 25.6 = 218.4 range ; W 244 / B 25.6 = 9.5 RGB CR
Black Screen W 99.3 - B 1.6 = 97.7 range ; W 99.3 / B 1.6 = 62 RGB CR
Gray Screen W 232.3 - B 24.3 = 208 range; W 232.3 / B 24.3 = 9.55 RGB CR

Sorta close, but not as close as I thought it would be. The range and the RGB CR are a lot closer between the white screen and the gray screen in my numbers.

Then I went back to the first post and sampled the brightest white and the darkest black in the sports bar screen that has the three sportscasters in it. Here's what I got.

Moderate ambient light "Comparing Bonds and T.O." sports bar image:
W 249 244 247 (papers in front of center guy)
B 42 42 38 (crook of arm of center guy)

W 249 244 247 avg 246
B 42 42 38 avg 41
W 246 - B 41 = 205 range
W 246 / B 41 = 6 RGB CR


Then I used Bud's numbers on the high ambient lit screens and did the RGB CR calculation with them.

Ambient lit screens:
White screen W 242 - B 102 = range 140; W 242 / B 102 = 2.4 RGB CR
Black screen W 78 - B 13 = range 65; W 78 / B 13 = 6 RGB CR
Gray screen W 227 - B 102 = range 125; W 227 / B 102 = 2.2 RGB CR


Looking at the screenshots and the numbers, here are my thoughts.

Using this RGB Method:
The Silver Fire screen maintains contrast ratio in moderate ambient light almost as well as the white or gray screens do in lights out conditions, and definitely does much better than the white or the gray in high ambient light conditions. (How much difference in ambient light there is between Bud's room and the sports bar I don't know, but from the look of the background it looks comparable. It would be good to test in identical conditions.)

While the black screen has the best RGB contrast ratio, the range (gray scale?) is small compared to the other screens, and is not acceptable for viewing. It just plain looks ugly.
I think that the range from light to dark is a much better measure of "perceived" contrast, and how happy we are with our screens. It looks like a good standard to use would be the "range" number. The higher the range, the better the image on the screen looks.

To recap, using Bud's numbers from his test:
Lights out screens:
White screen 216 range
Black screen 103 range
Gray screen 217 range
Ambient lit screens:
White screen 140 range
Black screen 65 range
Gray screen 125 range
Ambient lit Silver fire screen: (my numbers)
Silver Fire 205 range

What do you guys think?

By the way, Bud, great idea. Extremely useful.

(Can someone do a "black and white" of the three sportscaster shot?)

Tgreenwood


Tgreenwoods

Excellent post and thanks for adding the missing link in the form of the RGB-CR and what is a ratio but a fraction. For anyone out there trying to muddle thru this what he's saying is by dividing the average black RGB value into the average white value we get the number of times W is larger than B and that's a Ratio. Its somewhat limited by the range of number the RGB scale is broken down into. And I'm sure it is greatly limited or affected by the accuracy of the cam and the eyedropper testing. But nonetheless it could be several times better than what we do when comparing these screen shots by eye on un-calibrated monitors. The data in the image is there no mater how messed up the monitor is.

The reason for your different measurements than mine is simply by what pixel we happened to sample in an area. When I zoom in on a spot that's black say it's a black plaid of pixels jumping around 10 to 20 RGB points sometime. And we know JPG compresses the data also. But if you wanted to get closer maybe there is software that samples a block of pixels and comes up with an average. I'm pretty sure mine just hits a pixel. Ether way a semi scientific approach like this, one has to realize the term significant digits and not read more information into the final numbers than what they are worth. I do though think it's a way of steering the ship of our thoughts when experimenting.

As to comparing anything outside a given image when it comes to screen shots I have always said all bets are off. For instance if we come up with a number for a RGB_CR for MM ambient light screen shoot I would think it somewhat valid if compared to other samples in the same screen shoot, somewhat less valid if its in another screen shot but in the same room and of the same projected image in two photos but of different screen materials, and lastly vary invalid if comparing two numbers one from my room and one from MM room with two different cams etc.

This is why I proposed the method of taking screen shots some like Tiddler has been using for a year now of doing things within a photo and then making our understanding of what we learn by doing ABC comparisons within just one photo but comparing trends with other photos. We have to weigh the importance of observations within a photo much different than photo to photo.


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post #107 of 162 Old 05-21-2007, 04:45 AM - Thread Starter
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Here are those side shots. One thing that has become very apparent. That 'Ol MMud-LF screen does pretty damn good in ambient light with a PJ with 15,000:1 CR when the program source is also excellent. At least some Kudos must go to the JVC's "real Life" lumen output because the scene shown is not very vivid at all. Also, before I get more comments about the "Sky", go look at the Movie in the dark. The hue of the sky is much more akin to the SFLF sample's representation as shown in the Ambient Light shots. In the Dark, there is more darking of the Sky's hue, but not what you would call a "Crush". Also you'll note that the very noticeable "yellow" cast created by the Incandescent Cans is gone in the SFLF example One has only to observe the extreme difference in the "Bars" as far as the depth of "Dark" improvement.

This one shows the degree of Ambient light present.




From the Left



From closer Left



From the right




Ok, now what "Blubber Butt" wants to take the first "Bite"?



PS, look at the right side of the Penguin's face. You'll see that the degree of "Blueing" caused by the SF is really extremely slight given the drastic difference in hue between the White LF and the much Grayer SFLF. But on the opposite side of the Bird's face, the Blue shade as presented by the film is augmented. This means that SF does more to improve colors than to push them into directions they should not go. Only in the case of the most brightest of whites or lightest of Grays does the "blueing' manifest itself, and then it is only noticeable under direct comparison to a actual White. One can expect even less of a concern with a more reasonably lighter hue of SF.

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post #108 of 162 Old 05-21-2007, 11:07 AM
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MM

I had a few minutes to look over the comparison screen shots and thanks for the off angle shots as well.

Both the screen and the sample look like they hold up well to a side seating position.

In all the photos there is a part of the screen above and below the image being projected of just the screen where the projector is doing self masking. I compared that area with the eyedropper tool to the area in the image below it that was showing the deepest blacks. And in both screen samples the black dropped off just a few points from projector black to image black. About the same in both screen samples. I did the same with the brighter spots that being side by side should be about the same leaving the projector and saw about the same point drops I saw in the blacks sample top sample.

So the two samples are working as one would expect a white or light gray compared to a darker gray. Just as PB stated above. Same relative CR just shifted in one direction. Without a calibration and or a different image it's hard to say what sample is best suited to that projectors lumens.

Maybe Tgreenwood will repeat what I just described and confirm what I'm saying.

Comparing a metallic to a metallic I'm guessing should work like this. Right?

The biggest impact is in the lights out images and in those you can see the dark sample may have gone to far into the dark range base on the lumens available. That shows best on the first batch of pictures you posted. And would be closest to what the black material was doing in the screen shots I posted.


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post #109 of 162 Old 05-21-2007, 01:39 PM
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Any chance of posting a screenshot of a black and white checkerboard pattern?

It is difficult to pick consistent black and white samples from movie screenshots.

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post #110 of 162 Old 05-21-2007, 04:49 PM
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I'm going to throw my 2 cents worth in here.

Firstly, a simple picture of the issue of black to white and subjective grey.



So we all know about this ilusion created by our sensors.

The fact cannot be ignored we adjust out sensors depending on light conditions.
We also fool ourselves as we manufacture the overall result on the dominant feature. If the grey bar in the above picture covered a greater area the effect is lessened to the point where we would see a consistant grey bar.

The simple way to make black appear deeper is to resolve it next to grey.

Compare these 2 shots. (actually 7 but I'll get to that next)





Another pair with some light greys and whites.





Ok see the effect of grey border on perception of black or light greys and white.

The next issue is additive error.
If you take shots with cameras on auto the results will be varied. I tested this and found quite a difference in the returned photo on the perception of black or white. Basically the camera builds shades by time and light input.
The 2 shots that proff has greyed out appear to me to have different time exposures. A fraction of a second creates quite a difference.

I am not arguing that BF doesn't work, but the deception of the camera can alter the appearance.

I discuss this idea in my sig with filters. I calculated that the BF style screen with a mirror returns aprox 5% less loss of the original source. Note how I don't mention the word gain. Personally I find the word gain with screens contridictive.

Finally I will add my last 1 cent.

Light works in log.
Light will be absorbed through a subject in log.
But the difference between 2 grey shades for example will be more linear, but because they absorb in log the darker or more absorbant shade will absorb the light sooner than the lighter shade.

The effect of filters or clear material is to leave bands of light alone and not absorb those wave lengths.
The effect can be seen in my sig experiment.

Now the effect of throwing material up to to be subjected to comparisons is subject to the roll of dice chance factor. If the projector happens to be more aligned in RGB balance(delta E to be specific) with one material it will be visually be better to your eyes and the camera. But won't really be reality be better at all.

Heres the effect in reality of the above shots I took.
All shots of the above were taken with a fixed settings btw.

I measured and calibrated all the various panels and the result is clear.









One final thought about ambient light which I have noticed in alot of these comparison shots.
Ambient light can come in many forms, the 2 most important is diffuse and direct.
Down lights are wonderful for home theatres as they very directional lighting with little diffuse light.
But if you used just 1 standard 100w light bulb postioned 2metres from the screen you would kill it.

cat amonst the pigeons.
meeow

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post #111 of 162 Old 05-21-2007, 06:06 PM
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Found few cents in my pocket

I have used luminance graphs before to estimate absoption. They actually compare with my actual luminance readings.





Note the major issue with using darker shades or highly absorbant shades is the top end hit effect. You lose the same ratio from the top as bottom. We resolve this as the shades of white hit, or dynamic range, or Contrast.

My next screen will be somewhere around RGB 200, but will use a highly absorbant middle grey border. Rather than black border.

The idea being, perception of deeper black levels on screen relavent to the border, the adjacent shade judgement factor. The white level will not be hit by the dark grey absorption factor.

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post #112 of 162 Old 05-21-2007, 06:18 PM
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i'm glad to see some civil discussion going on... finally...
...which gives me reason to share these screenshots to add to the discussion.

the first is a comparison in daylight of an early sf/bf screen vs. a panny.

it's the reason i no longer have anything other than pj's and lcd's in my house. it was close enough to no longer need the panny. i gave it to my aunt.


the second reiterates what bud and mm said earlier. ...and one of the things i've said about sf/bf is that colors aren't so much shifted as they are richer & more saturated.

here the background is a upw wall... and while the hue of the color remains basically the same... the colors are instead enriched. the white levels are ever so slightly less but the black levels are greatly enhanced.

smokey,
and finally, while i agree with nearly everything you said... i can show some screenshots that do contradict an uncovered light bulb completely washing out a sf/bf screen.



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Quote:
Originally Posted by kbgl View Post

Poor me. I'm on dialup and can't view many of the screen shots of these pages, because they never finish loading. If anyone can delete some of the redundant pictures, or reduce the size or resolution a little, I would be grateful.

I almost posted to this same thing and I'm on a very fast internet connection. The photos I have been linking are actually thumbnails and are a reasonable size for scrolling past and if anyone wishes to see them huge scale they only have to click on them. Tiddler started a thread about this a while back and several of us gave some input .

My problem is many of the posted photos are so wide it exceeds the width of my monitor and then I get into side scrolling to read the text.

Anyone quoting a post with a photo unless its really important should take the time to clip out the link.


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post #114 of 162 Old 05-22-2007, 09:33 AM
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I believe most browsers have a way to limit or disable images so that pages load faster. This might be worth investigating if you're having problems.

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post #115 of 162 Old 05-22-2007, 09:40 AM
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Quote:
Originally Posted by pb_maxxx View Post

i'll try to reduce the file sizes if i can... hopefully without effecting them too much...

I don't really see any issues with any of the ones you have posted PB.

Most of mine are 600x452 and I would think around the 600 number is good for viewing and also loading for the guys with slower connections. Much smaller and they not of that much use for seeing what is going on.


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Quote:
Originally Posted by bud16415 View Post

I don’t really see any issues with any of the ones you have posted PB.

Most of mine are 600x452 and I would think around the 600 number is good for viewing and also loading for the guys with slower connections. Much smaller and they not of that much use for seeing what is going on.

Well... They all finally loaded, and I deleted my post, but it would be nice in general if the sizes could be kept down a little. I know it's hard to make a screen shot impressive at lower resolution, but if the color or contrast is the focus of the post, then resolution should not matter all that much.

No offense pb_maxxx, just used your excellent photo as an example. It's now one fourth the file size, and I think makes the same point.
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post #117 of 162 Old 05-23-2007, 05:24 AM - Thread Starter
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Quote:
Originally Posted by kbgl View Post

Well... They all finally loaded, and I deleted my post, but it would be nice in general if the sizes could be kept down a little. I know it's hard to make a screen shot impressive at lower resolution, but if the color or contrast is the focus of the post, then resolution should not matter all that much.

It is hard to satisfy everyone. The future is High Speed. But many lag behind, some for reasons not of their own choice.

It Ok to ask people to try to accommodate one's technological failings, but not OK to expect it out of hand. This comes up only once and a while, and although I can sympathize, I do not agree with the need to change for the few select individuals who feel the need to complain about waiting for images to load. And even less about comments that image quality do not matter. It does. No one wants to bother posting up images that do not impress or serve to represent irrevocably what is being seen in person by the Poster.

Resolution DOES make a difference. So does Focus. And using the correct settings. Quality shown DOES catch the eyes more than snap shots that look like they came from a Disposable Camera. High quality images leave nothing (...or little....) to be imagined, leastwise not as much as many would tout if the images shown were of the nature of the quality off your sample.

If you doubt it, consider how many consider the relevance of what is offered by the quality of the image shown online. Poorly done shots do not garner attention, and that my Friend is what getting the word out is all about. Attention.

Clarence's screen shots of his Designer White screen are held up to be the absolute best yet, (he's got a G90 CRT though....) and that surely would not be the case if he worried about file size and posted images shot at 800x600 and then reduced them to 480x320. because of those shots, he proves the value of such a DIY application over a much more expensive, and previously heralded "as best" Mfg. screen, the StudioTek130. It wouldn't have happened otherwise.

The detail and subtle Color and Contrast variances shown in high resolution images do not come out of nowhere, and they most certainly would be lost to the method you prescribe to.

It boils down to this, people want an accurate visual representation of what is being espoused. We get enough flack about how Digtial imagery does not represent the "Real World" as it is without setting the stage for more adverse comments by reducing image quality. This is the era of High Definition, in a time where a 5 MP Camera can be had for close to under $100. Most people expect more from us who work to bring info to share, not less. yes, there will be some cannot handle it, but they are among the few, not the majority, when it come down to who frequents these Forums.

Back when we all just "attached" images, there were in fact some real issues involved. I watched a few forward thinking Souls create images that loaded from remote File Storage servers, and jumped on that as quickly as possible. I shoot at 2560 x 1920, reduce the image size AFTERWARDS to 800x600 or even 600x452. That small difference between the two latter figures does not do a lot for loading times, but it does allow the image to fit into the screen without scrolling.

Unless one has a 14" monitor. Then we'll hear from that person about his PC woes as well.


I do sympathize, but I cannot justify sacrificing visual quality for the convenience of a relative few. Bud's thumbnail method is perhaps the route I'll take eventually, but if someone is gonna complain about loading times, they are still waiting for them after the "click" anyway. The only real advantage, and I'll agree it's one to be considered, is that the entire page including all the written posts, will load faster. That does remain as a valid concern for many, and frustration that sets in while waiting for a Thread that contains a tremendous amount of Photos is really at the root of your complaint, not any one such example.

This is why I myself have taken to posting coloages whenever possible.

You want to take aim at something abusive....then go shoot at those who post entire pages of continious imagery. I recently saw someone with 9 consecutive posts, each spaced under 2 minutes apart, each with at least 4-5 large images.

At least in the past if I had a thread with lots of images I posted a "Image Intensive" warning in the thread's title. A few still complained though.

As I said earlier, it's all about getting people's attention, and unfortunately we all know a few who go way over the Top in doing so.

I'll keep your concerns in mind however, and consider them more strongly than my posted comment indicate.

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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post #118 of 162 Old 05-23-2007, 11:38 AM - Thread Starter
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Thanks Tiddler,

That's the "Rock upside the Head"
I neededm and a good example of empowerment though education.

I'll use it judiciously.

MMan

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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post #119 of 162 Old 06-02-2007, 02:15 PM
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Wasn't there supposed to be some"irrefutable evidence" that was going to be presented? Maybe I missed it.

Meow.
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post #120 of 162 Old 06-02-2007, 02:35 PM - Thread Starter
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No, it's still on the "soon to come" agenda. But undisputedly more pressing events have occured that need must draw my attention from such "irrefutable" endeavors.

But thanks for "The Bump". I'll keep it at the top of my list of things to do after my trip west.

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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