Time to define an alternative to ANSI contrast? - Page 4 - AVS Forum
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post #91 of 341 Old 12-30-2006, 09:39 AM
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Ah yes this is what i have been waiting for, great work all of you, cant wait until we have numbers between PJ using these patters

Cine4home, did you use similar test patterns as the ones in the thread, what do you mean with "real world pictures" could you elaborate on how the patterns looks.

And also, on which patterns did the DLP show better and on which the SXRD.
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post #92 of 341 Old 12-30-2006, 11:07 AM - Thread Starter
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Quote:
Originally Posted by Cine4Home View Post

We started measuring some "real world" pictures with one SXRD Projector (4000:1 / 240:1) and a DLP "(2000:1 / 540:1). The results were very surprising. In some Scenes, the Pearl showed more intra contrast, in others the DLP.

Hi Ekkehart, I would also like to second Zoomair's question. Can you provide some more info about your methodology? How did you measure contrast with "real world" pictures?
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post #93 of 341 Old 01-03-2007, 07:38 AM
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Quote:
Originally Posted by Mark Petersen View Post

Hi Ekkehart, I would also like to second Zoomair's question. Can you provide some more info about your methodology? How did you measure contrast with "real world" pictures?


This was just one first experiment, no fully dveloped method yet. What we did was:

a) Measure ON / OFF contrast: Pearl was 4000:1, DLP was 2000:1

b) Measure checkerboard contrast: Pearl was 240:1, DLP well over 500:1

c) Measure contrast in typical movie scenes: Dark ones with low APL, light ones with higher APL and so on. We chose light and dark areas in each picture and mesured the contrast.

d) The results showed clearly, that intra-contrast hardly can be predicted. In lower APL scenes the Pearl clearly won, in higher it was sometimes even, sometimes the DLP won.


If you guys are interested, I might write an article about that experiment.

Regards,
Ekkehart
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post #94 of 341 Old 01-03-2007, 07:49 AM
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Hello Ekkehart:

I generally do not have nearly enough specific knowledge to jump in on threads of this nature, but I will say, I find all the reading to be extremely informative and fascinating.

I for one woud greatly appreciate it if you would write an article about this experiment.

Thanks and regards.

Disclaimer: Totally biased RS1 fanclown...cannot be relied upon for any type of objectivity regarding same. You have been warned.
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post #95 of 341 Old 01-03-2007, 10:42 AM
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Quote:
Originally Posted by Cine4Home View Post

If you guys are interested, I might write an article about that experiment.

Regards,
Ekkehart

Ja gern bitte Ekkehart

Grégory

Visit the new pjhc.fr forum here : http://www.projection-homecinema.fr/forum/
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post #96 of 341 Old 01-03-2007, 05:34 PM
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I measured a JVC HD2K projector using the "APL CR" test patterns.

Code:
Pattern Reading Ratio
RefWhite        1733.7    - 12 inches from projector
1%      1.512   1147
5%      2.977   582
10%     5.075   342
15%     6.807   255
20%     7.63    227
                
FullBlack       0.82    
FullWhite       1679.2  2048


RefWhite        835.9   - 18 inches from projector
1%      0.678   1233
5%      1.369   611
10%     2.589   323
15%     3.125   267
20%     3.536   236
                
FullBlack       0.395   
Full White      804.59  2037

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post #97 of 341 Old 01-03-2007, 06:05 PM
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Some numbers for a Sony VW50. Iris 1, Lamp high, adjusted for D65, max output without clipping. Measured at 18 inches from projector.

Code:
Ref White       637.95  
1%      0.225   2835
5%      1.304   489
10%     2.128   300
15%     2.604   245
20%     3.014   212
                
Full Black      0.134   
Full White      1970.36 14704

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post #98 of 341 Old 01-03-2007, 06:09 PM - Thread Starter
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Quote:
Originally Posted by wm View Post

I measured a JVC HD2K projector using the "APL CR" test patterns.

Code:
Pattern Reading Ratio
RefWhite        1733.7    - 12 inches from projector
1%      1.512   1147
5%      2.977   582
10%     5.075   342
15%     6.807   255
20%     7.63    227
                
FullBlack       0.82    
FullWhite       1679.2  2048


RefWhite        835.9   - 18 inches from projector
1%      0.678   1233
5%      1.369   611
10%     2.589   323
15%     3.125   267
20%     3.536   236
                
FullBlack       0.395   
Full White      804.59  2037

Good deal thanks Wm! If you get a chance to measure ANSI CR that would help too. Oh yeah and I can't wait for your measurements on any other projectors that you can get your hands on. The analysis of this data should be most interesting and revealing.

EDIT: Looks like I spoke too soon. Thanks for the numbers on the VW50 as well.
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post #99 of 341 Old 01-03-2007, 06:13 PM
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I've been watching this (hoping to see measurements from projectors in addition to the stimulating conversation ). What are you using to make these measurements (that's something that's been on my want-list).

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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post #100 of 341 Old 01-03-2007, 06:18 PM
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Quote:
Originally Posted by Cine4Home View Post

This was just one first experiment, no fully dveloped method yet. What we did was:

a) Measure ON / OFF contrast: Pearl was 4000:1, DLP was 2000:1

b) Measure checkerboard contrast: Pearl was 240:1, DLP well over 500:1

c) Measure contrast in typical movie scenes: Dark ones with low APL, light ones with higher APL and so on. We chose light and dark areas in each picture and mesured the contrast.

d) The results showed clearly, that intra-contrast hardly can be predicted. In lower APL scenes the Pearl clearly won, in higher it was sometimes even, sometimes the DLP won.


If you guys are interested, I might write an article about that experiment.

Regards,
Ekkehart

Very interested would be very nice with an article.

And even if you don't write the article, please post all of the numbers from this experiment, would be nice to see.

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post #101 of 341 Old 01-03-2007, 07:00 PM - Thread Starter
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Quote:
Originally Posted by Cine4Home View Post

This was just one first experiment, no fully dveloped method yet. What we did was:

a) Measure ON / OFF contrast: Pearl was 4000:1, DLP was 2000:1

b) Measure checkerboard contrast: Pearl was 240:1, DLP well over 500:1

c) Measure contrast in typical movie scenes: Dark ones with low APL, light ones with higher APL and so on. We chose light and dark areas in each picture and mesured the contrast.

d) The results showed clearly, that intra-contrast hardly can be predicted. In lower APL scenes the Pearl clearly won, in higher it was sometimes even, sometimes the DLP won.


If you guys are interested, I might write an article about that experiment.

Regards,
Ekkehart


Hi Ekkehart,

Thanks for posting, this was exactly the sort of discussion that I was hoping to hear when I started this thread. An Intra-scene contrast measurment is problematic for many reasons one is that it's gamma depdendent and a standardized benchmark could be easily swayed by the calibration. Probe alignment and filling the probe with a consistent image also seem to be key in this approach. Another problem is scaling the test patterns so that consistent measurements between 720 and 1080 displays can be obtained. Despite these issues though I'm very keen on reading the data that you've obtained. So please do post the results via an article or on AVS.
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post #102 of 341 Old 01-03-2007, 08:06 PM
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Quote:
Originally Posted by wm View Post

Thanks for the interest - I think this is a very worthwhile effort! With everyone's feedback we can produce something really useful here.

Full field black and full field white are already included in the set.

I am going to try to add 15% APL today, then send out a copy to those that requested it.

I am considering adding my resolution test pattern to the set. If I do this it will have my trademark in it, since I developed it. The license will require that this not be removed. You folks cool with that?

William

Sounds very appropriate.

I am trying to fully understand the process with the test pattern. If the light meter probe is placed facing the projector, centered in the test pattern in line with the light path, say the 10% pattern, we are then trying to read the lumens of the black center. How are we to insure that the angle of view of the light meter is not picking up any of the white squares?

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post #103 of 341 Old 01-03-2007, 09:03 PM
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Quote:
Originally Posted by stanger89 View Post

I've been watching this (hoping to see measurements from projectors in addition to the stimulating conversation ). What are you using to make these measurements (that's something that's been on my want-list).

I use a Progressive Labs CA-5, which is a USB attached colorimeter. This is a new piece from Cliff, replacing my old CA-1. It has a very wide range and gives very consistent readings. I use my own software to generate the test patterns and take the readings.

William

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post #104 of 341 Old 01-03-2007, 09:17 PM
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Quote:
Originally Posted by Mark Petersen View Post

Good deal thanks Wm! If you get a chance to measure ANSI CR that would help too.

Mark,

I clearly need to add a pair of ANSI CR test patterns to the set - because they are not there, I forgot to take that reading. I'll do that.

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post #105 of 341 Old 01-03-2007, 09:23 PM
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Quote:
Originally Posted by GlenC View Post

Sounds very appropriate.

I am trying to fully understand the process with the test pattern. If the light meter probe is placed facing the projector, centered in the test pattern in line with the light path, say the 10% pattern, we are then trying to read the lumens of the black center. How are we to insure that the angle of view of the light meter is not picking up any of the white squares?

The meter has a cosine receptor, not a lens. It reads light that falls on the receptor. It shouldn't see any light coming directly from the squares.

It is important to make sure that there aren't any reflections, from the probe or anything that is holding it, or the ceiling, etc. I've got a sheet of black velour cloth attached to the ceiling as a mask for the front of the projector.

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post #106 of 341 Old 01-03-2007, 11:25 PM
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Below are the results from my Sharp 10K. I did this by hooking up my PC, setting it at 720p and outputting that natively via DVI to the pj. I displayed the 1920x1080 images using William's suggestion of IrfanView at full screen, letting the program do the scaling to 1280x720.

Tip: There are options under the Settings to hide the mouse and remove the file labels from the screen when in full screen mode. William this program was a great call - made it very easy and you can scroll in full screen mode easily between images.

These readings were taken with the AEMC 813 mounted on a tripod 20" from the pj lens. I had velvet around the instrument to reduce settings. However I did not put anything up on the ceiling, and with hindsight after reading the above this really is necessary as there was likely some light reflecting back. I'll retake these measurements someday (total PITA moving my PC to the HT...) but in the meantime this will give us a good starting point as I don't think the results will be much different.

Sharp 10K
Bulb hours: 80
Meter location: 20" from pj lens

All readings are in lux:
Full white screen: 4499
Ref white square: 4499
Black ref: 2.6
1%: 3.31 | 1359:1
5%: 4.27 | 1054:1
10%: 6.08 | 740:1
15%: 6.73 | 669:1
20%: 7.23 | 622:1

ANSI CR: 279:1
ON/OFF CR: 1730:1

--

Also I've been working hard to control my room reflections (velvet now on ceiling, dark throw rug on the floor) so I was very interested to see how well my contrast readings were doing at the screen...

Here are the same measurements, except this time the meter was POSITIONED AT THE SCREEN:

Meter location: At the screen

All readings are in lux:
Full white screen: 63.9
Ref white square: 63.5
Black ref: 0.03
1%: 0.04 | 1588:1 (basing these off of 63.5 not 63.9)
5%: 0.06 | 1058:1
10%: 0.09 | 706:1
15%: 0.11 | 577:1
20%: 0.13 | 488:1

ANSI CR: 185:1
ON/OFF CR: 2117:1

Referring back to the measurements taken at the pj (first set listed in this post) its interesting to see DLP maintain its strong advantage in contrast over SXRD and LCoS based on William's posted numbers for the HD2K and the Pearl.

Please let me know what you guys think about these results.

Also are there any conclusions we can draw about how effective my room reflectivity reduction efforts are being, based on the results reported for measurements at the screen?

I'm not sure if there is merit in the following comparison, but what I decided to do was measured AT THE PJ the % drop in CR as I moved from one APL to the next, and compare that to % drop in CR as measured AT THE SCREEN:

Moving from 0 to 1%: 21% drop in CR at pj VS. 25% drop at screen
1% to 5%: 22% drop at pj VS. 33% at screen
5% to 10%: 30% drop at pj VS. 33% at screen
10% to 15%: 10% drop at pj VS. 18% at screen
15% to 20%: 7% drop at pj VS. 15% at screen

I don't think there's much value in the % drop data comparison above in isolation like this. However it would be very interesting to see what OTHER PEOPLE got in their rooms at the screen % drop-wise. I'm thinking that it wouldn't even matter what pj it was or what its CR capabilities were because we're comparing the drop off in CR at the pj % wise vs. at the screen.

For instance if the ratio of someone's % drops at their pj vs. % drop at their screen was better than mine, we could conclude they had better light control, and vice-versa. With enough sample sizes we may even be able to come up with a relative baseline for poorly treated rooms (reflectivity control-wise, average treated rooms, and well treated rooms). People could then compare their results to see how well their room reflectivity control is versus others.

I know we are discussing two different things here. In one case we are talking about the native CR capabilities of the pj itself. And in the other case we're talking about what the user can expect to ACTUALLY EXPERIENCE when watching a movie. Both types of readings have great merit, so I'd like to see us develop this scale (actual experience on the screen) along with the scale being used to measure a pj's capabilities (without the room factored in).

Thoughts?
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post #107 of 341 Old 01-04-2007, 05:05 PM
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Some numbers for a Sony VW50. Iris 1, Lamp high, adjusted for D65, max output without clipping. Measured at 24 inches from projector.

Code:
Sony VW50, Iris 1, Lamp high, 24 inches

Ref White       362.2           
1%      0.125   2898    
5%      0.733   494     
10%     1.154   314     
15%     1.425   254     
20%     1.658   218     
                        
Black   0.078           
Full White      1115.5  14301   On/Off CR

ANSI hi 1121.5  
ANSI lo 4.196   267     Modified ANSI CR

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post #108 of 341 Old 01-04-2007, 05:09 PM
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And finally, numbers for a JVC HD1, lamp normal, adjusted for D65, measured 24 inches from the projector. (this may not be a "production" unit)

Code:
JVC HD1, Lamp normal, 24 inches

                Ratio
Ref White       817.52          
1%      0.171   4781    
5%      0.39    2096    
10%     0.751   1089    
15%     0.952   859     
20%     1.126   726     
                        
Full Black      0.067           
Full White      778.03  11612   On/Off CR
                        
ANSI hi 853.6           
ANSI lo 3.131   273     Modified ANSI CR

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post #109 of 341 Old 01-04-2007, 05:25 PM
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WOW William great, thanks for those numbers, and also thanks to lovingdvd.

Does someone have similar numbers for a High End DLP with high ANSI contrast, would be cool too compare, and also dare I say it a CRT.

Very interesting too see the difference between iris-contrast and native contrast (Pearl vs JVC). And i think we can be pretty sure now that the JVC is around 300 in ANSI contrast.

Interesting comparing lovingdvd numbers to Williams for the Pearl, the Sharp 10k with a similar ANSI reading and lower ONOFF reading still produces more contrast at almost every "step", of course it would be more accurate if the numbers came from the same source, but still quite interesting

I must say this is a great thread.

Now we crave more numbers
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post #110 of 341 Old 01-04-2007, 05:40 PM - Thread Starter
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Baddabing! Thanks Wm and Lovingdvd for posting these numbers. Hopefully we can get Darinp2 or someone else with a high ANSI CR DLP to post some numbers too. This thread will really cast some light on contrast (sorry I couldn't resist)...
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post #111 of 341 Old 01-04-2007, 05:53 PM
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My thanks and complements to wm and lovingdvd for all the work you are doing in this area. I think you are developing a test suite that may finally give us meaningful measurement tools that will allow us to comparing projectors for that illusive quality most people here call "picture depth".

Congratulations on the work you have done so far and best wishes for your continued success in this area.

"I'm a fanatic without a cause and I believe in it!" - B. D. G.
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post #112 of 341 Old 01-04-2007, 06:31 PM
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fyi - I have ordered a CA813, in the hopes that the numbers will be more comparable that way (same size sensor, etc.).

I am going to suggest that people use a distance of 24" for at least one set of measurements. The distance should be from the front of the lens, measured as accurately as possible, to the front surface of the probe.

I have added ANSI CR test patterns to the set; email me for updates.

That's all for now, time to shut down and get packed for CES.

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post #113 of 341 Old 01-04-2007, 06:37 PM
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Quote:
Originally Posted by maddogmc View Post

My thanks and complements to wm and lovingdvd for all the work you are doing in this area.

And Mark!

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post #114 of 341 Old 01-04-2007, 06:37 PM
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Hi William and Mark and LDVD

Thanks for taking the time.

Gary

Quote:
Originally Posted by elmalloc
Who says Cameron is "right" and why do we care about him so much - lol!

I trust Gary Lightfoot more than James Cameron.
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post #115 of 341 Old 01-04-2007, 06:49 PM
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Quote:
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And Mark!

SORRY MARK! And Mark!

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post #116 of 341 Old 01-04-2007, 06:52 PM
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Quote:
Originally Posted by wm View Post

fyi - I have ordered a CA813, in the hopes that the numbers will be more comparable that way (same size sensor, etc.).

I'll be interested to hear what you think of it. I've had two with issues where they seem to have some kind of leakage where they have a non-zero offset or read values with the cap on with light hitting the back of the top portion (not the sensor part). For instance, one I just got new reads something like 0.07 lux with the light on in the dark and the cap on it. This seems to be an offset in the negative direction where a little bit of light moves it toward zero and then it goes up from there.

BTW: If anybody wants to test the theories about projectors not needing to do more than 100:1, 200:1, 300:1 simultanteous CR (or whatever number somebody uses), they can use William's 1% or 5% pattern with black velvet or black posterboard up on a dark part of the screen, or use their hand to block part of the dark part and see how easy it is to make out vs the "black" from the projector and room. As the measurements here show, getting over 1000:1 simultaneous CR from a projector with a pattern like the 1% one is not that uncommon.

--Darin

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post #117 of 341 Old 01-04-2007, 07:06 PM - Thread Starter
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Quote:
Originally Posted by wm View Post

fyi - I have ordered a CA813, in the hopes that the numbers will be more comparable that way (same size sensor, etc.).

I am going to suggest that people use a distance of 24" for at least one set of measurements. The distance should be from the front of the lens, measured as accurately as possible, to the front surface of the probe.

I have added ANSI CR test patterns to the set; email me for updates.

That's all for now, time to shut down and get packed for CES.

William

I'll be interested in hearing what you think of the CA813 too. Hopefully there won't be a lot of deviation between units so that we can get accurate numbers from members.

Also for future posts of projector performance I would recommend that people supply the following pieces of information:

Model #
APL Percentages for (0%, 1%, 5%, 10%, 15% and 20% test patterns) (0% being defined as Ref White/ Full Black - and not to be confused with On/Off).
ANSI CR
On/OFF CR (Full On / Full Off)
Ref White Reading
Full White Reading
Full Black Reading
Probe Distance (24" strongly recommended)
Reviewer Name
Lamp Setting
Lamp Hrs
Comments


Also note that this assumes a D65 calibration and that the white and black points have been set correctly.

Also of interest although a lot more problematic is measurements from the screen. Although results will be heavily effected by the room environment it will show how room effects for a given room will impact contrast as a function of luminance. So I would recommend that people perform similar measurments as above but off of the screen instead and also provide some insight into their room environment, screen type and gain in the description. Probe distance is TBD for now.
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post #118 of 341 Old 01-04-2007, 07:19 PM
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Opps sorry, i miscalculated
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post #119 of 341 Old 01-04-2007, 08:02 PM
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Ok, now that we have some numbers, lets compare to the calculator.

Have I understood right if 15% from the readings is equal to 30% area covered in the calculator and then looking at the 100% line.

Dont know at what gamma these numbers are, for the calculator i choose 2,5.

But what should you select for the room reflectivity, since these numbers where measured against the projector and in what i have understood it good rooms, than you should be able to lower the room reflectivity number to e.g. 0,001.

Here you have some numbers from the calculator, the numbers in the parenthesis are Williams number for the JVC (ruffly rounded)

At 0,001 RG

1: 5900:1 (4800:1)

5: 2000:1 (2100:1)

10: 1100:1 (1100:1)

15: 750:1 (860:1)

20: 550:1 (720:1)
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post #120 of 341 Old 01-04-2007, 08:07 PM
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Interesting to note that the modified ANSI contrast numbers for the Pearl and RS1 are almost identical. I thought people were expecting more improvement from the RS1 in this area.

Could someone try to give a mini-course on what the "Ref White" and corresponding percentages indicate?

Sorry to show my ignorance here.

Does wm list the lumens output of the HD1, or is it in LUX?
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