[coderguy]

This is an attempt to find out if it is better for certain setups at certain room lighting levels to buy a projector with a higher ON/OFF contrast (typical of LCOS and LCD's with IRIS) or a higher ANSI contrast (typical of DLP's). The tests will be done on the Epson 8500ub, the Mitsubishi hc3800, and the older Sanyo Z5 (720p), all with varying ANSI and varying ON/OFF contrast ratios. This test could actually be done with only (1) projector if we wanted, but we will be using 3 projectors for comparisons to make it more interesting and to possibly make the results more reliable.


Note that the main purpose of this test is not to compare the (3) projectors so much (this is only one of the comparisons I will be doing), but it is to specifically identify how a given contrast number is affected by a given lighting condition, and how this directly relates to the visual perception of the image at these given numbers.


Now please feel free to post any comments on ON/OFF vs ANSI that you may have and DO NOT worry about filling this thread up with general info, because once we get the final testing numbers and have concluded the test was valid, I will then create a new thread just for the numbers themselves....


So let's start the partisan projector and ON/OFF vs ANSI FIGHT!!!

(cough cough I mean friendly debate).

 

[coderguy]

So the 3 room lighting conditions might be something like this:


1) 80% Darkened Room (white ceiling, black curtains on walls, black throw carpet, some light colored carpet around the perimeter, some white still showing from small parts of the wall)


2) 95% Darkened Room (black sheet on ceiling, black curtains on walls, black throw carpet, some light colored carpet around the perimeter, some white still showing from small parts of the wall).


3) 100% Darkened Room (everything painted pitch black, or in my case I will use 4 poles and temporarily wrap black sheets around them to block 100% of the light, so I will create a sort of inner cave in my already darkened room which should provide 99% to 100% darkness)


Tests will be conducted first on a white wall, a darker tan wall, an Elite 84" screen with a black border, and MAYBE last with a 106" High Power screen. I may also mix the results between the four viewing materials as to provide more validity to the test.


If anyone has further conditions to add, let me know.

 

[danieledmunds]

It might be worth doing a test with one or two small lamps to recreate a normal living room environment. Perhaps take the 80% darkened and add a lamp at the back of the room?


Very interested to see the results of this, having owned LCOS and DLPs, the DLPs seem to be better with ambient light. Of course LCD could have come along in the last 2 years or so...

 

[coderguy]



Quote:
Originally Posted by danieledmunds /forum/post/18151561


It might be worth doing a test with one or two small lamps to recreate a normal living room environment.

Not a bad idea, but the purpose of this test is to see at what point of room lighting ANSI contrast loses its POP and how the relation between ANSI and ON/OFF matters in different reflective lighting conditions, but we already can assume it would be a relatively low amount of light that causes a major loss in image POP as dealing with ANSI contrast, but we just want to see exactly how much. So this test is for very minor amounts of light reflection such as light bouncing off ceilings and walls, rather than a test for ambient light. I might throw one or two ambient light tests in here, but I want to keep it to the main point as much as possible.


Some people have already tested the Epson 8500ub vs the hc3800 in moderate ambient light, and it is an easy win for the 8500ub, not only because you cannot use an HP screen for the hc3800 (unless you floor mount), but also because the 8500's mid-range modes have higher lumens than the hc3800 and so do it's brightest modes, not to mention we know that ANSI contrast is going to make no difference with a lamp on, and here ON/OFF contrast is the only thing that matters. So the Epson's higher lumens and higher ON/OFF, in addition to the ability to use a high power screen, will easily slaughter the hc3800 with any semi-significant amount of ambient light (now when we darken this to just reflected light in the room, that may become a different story).


The reason to compare reflected light is because many people cannot paint their ceilings or get the room 100% reflection proof. Also this will be split up into 2 reviews eventually, one will simply be an overall quality comparison of the 3 projectors.

 

[danieledmunds]

You said "not to mention we know that ANSI contrast is going to make no difference with a lamp on, and here ON/OFF contrast is the only thing that matters."


I have to say when comparing the RS1 which is around the same brightness as the Z15000 in "natural" mode, the Z15000 is far more watchable with either another light source or more reflected light. I am not sure if this because of ANSI or some other factor. Even my Optoma HD65 looked better than the RS1 with more light in the room.


The RS1 just looked flatter and washed out compared to the DLPs even though the on/of is much higher. Are my observations completely opposite of what the measurements would suggest I "should" see?

 

[airscapes]

Um.. no expert here but you will need to make sure all 3 projectors are calibrated identically and have the exact same amount of FL at the screen in total darkness before you start turning on light..


You will find a 4000 Lumen projector looks real nice in ambient light compared to a 1000.. so all 3 need to be identical for this to mean anything I would think.

 

[coderguy]



Quote:
Originally Posted by airscapes /forum/post/18152344


Um.. no expert here but you will need to make sure all 3 projectors are calibrated identically and have the exact same amount of FL at the screen in total darkness before you start turning on light..


You will find a 4000 Lumen projector looks real nice in ambient light compared to a 1000.. so all 3 need to be identical for this to mean anything I would think.

The test is for a small amount of reflected light, not so much purposefully introduced ambient light (although I may do a couple of ambient light tests, the main focus remains for reflected light). The colorimeter takes actual measurements of brightness, contrast, and color. Perfect calibration is only required for precisely comparing all (3) projector's best modes. That said I will do my best to calibrate these projectors very carefully. However, we should only need to get it fairly close so long as I take independant measurements for each projector and the measured numbers are what will make it relative.

 

[coderguy]



Quote:
Originally Posted by danieledmunds /forum/post/18152231


You said "not to mention we know that ANSI contrast is going to make no difference with a lamp on, and here ON/OFF contrast is the only thing that matters."


I have to say when comparing the RS1 which is around the same brightness as the Z15000 in "natural" mode, the Z15000 is far more watchable with either another light source or more reflected light.

My guess is this is more than likely that the RS1's mode you are comparing is just not as good as the Z15000's natural mode at the relative brightness level you have the projectors at. Even though a higher ON/OFF contrast number is better for dealing with ambient light, some projectors might LOSE their ON/OFF contrast numbers when you raise the brightness (so this is 2 separate issues). This is why I will be measuring the numbers with a colorimeter. I think JVC's tend to only produce good ON/OFF contrast balance at their lowest lumens and in extremely low lighting conditions, so once you get the contrast and brightness balance at a certain level the image becomes washed out. Remember that even though ON/OFF contrast is more useful than ANSI as the room light increases, also keep in mind that ON/OFF is still useful in black hole rooms as well (as opposed to ANSI which is only useful in black hole rooms). The main difference between ANSI and ON/OFF in black hole rooms is that the higher ANSI will make brighter scenes have more POP, while the higher ON/OFF in a bat cave should make darker scenes POP more (so ultimately you want high ANSI and ON/OFF and ultimately you want to always be in a black hole). The test here is to determine some ratio of how much reflected light starts to ruin some of this POP.


Some projectors have a tendency to maintain ON/OFF contrast at varying brightness balances, while some tend to only maintain this right near their BEST MODE (which is usually one of their dimmest modes). So this is a separate issue. What we are testing for is how things look with the actual measured ANSI and ON/OFF numbers, so we will be hopefully able to get past the BIAS these projectors introduce into contrast because we will be using real measurements of the contrast and brightness.

 

[coderguy]

To clarify this issue above, ON/OFF contrast is affected by the individual projector's contrast/brightness settings. So just because a projector has a higher ON/OFF in its best mode does not mean it will beat another projector's ON/OFF at varying settings.


This is the BIAS that will be introduced by these projectors and the primary reason I need a colorimeter to take the contrast measurements. What we are primarily testing for is not to compare the (3) projectors between each other (although this is the secondary test and is also important in a review sense), but we are actually going to be testing to see how differing ANSI and ON/OFF ratios look in varying light reflectivity conditions of the room. This test could actually be performed with only (1) projector. The (3) devices will be used to see if my eye sees similar POP results based on contrast levels for all (3) projectors when given near the same contrast at a given lighting condition (this is kind of hard to explain, but I will explain it better once I have the results).


I am now confident in my testing methodology and am going to try and order the colorimeter tonight.

 

[BKSRU]

Theme interesting.

I will try to express the opinion.

It is difficult to me to express not simple things in nonnative language. We often have rough debate concerning ANSI contrast vs ON/OFF contrast. There are some conclusions and supervision about it. I can give references to the original. If it will be not difficult to translate to you?


ON/OFF Contrast characterises a range of real contrast in a shot depending on light exposure of a scene of a film.

ANSI contrast is a special case. And it characterises ability of black fields of a shot to resist to a flare from light fields of a shot.

ON/OFF And ANSI contrast together give almost full picture of real contrast throughout all film display. But for a concrete projector.

The light stream characterises ability of real contrast to resist to an external flare (badly prepared room). It introduces the corrective amendments in subjective perception of real contrast.

It will be difficult enough to lead all factors to a uniform denominator. Otherwise conclusions will be not objective.


I hope me not difficult to understand.

 

[dovercat]

As you are going to be calibrating the projectors, can you provide the calibration results, along with your findings. I would expect the projectors gamma curve and grey scale tracking to effect the subjective image pop. Histograms of digital camera shots of test pattern like those done by http://www.videovantage.com/?p=11 would also be useful in showing the difference between the projectors mtf, which should also have an effect on perceived image pop.


In my opinion in dark scenes you need high contrast to keep the image looking dynamic. This can either be achieved by having a very good room with little ambient and reflected light, and a very low black level on the projector, so the low black level is maintained. Or by using a brighter projector whose black level is brighter than the washout level and so maintains its contrast to the bright white. The first method should look better as black is black your eyes/brain do not expect to see details in the pitch black, while the second method is less convincing as black is bright enough that your eyes/brain should be able to see details in it, but can not.

In bright scenes, brighter is better it increases the eyes contrast sensitivity particularly in smaller details where textural depth cues maybe, brightness also increases the perception of color vibrancy. So ideally you want dark dark scenes and bright bright scenes, high on/off contrast ratio is king. Ansi contrast ratio as long as it is high enough I would expect to be typically a non-issue as in a particularly image it is more likely to be image limited than projector limited. It is only important as a vague and unreliable indicator of projector mtf which will effect perceived image quality.

 

[coderguy]



Quote:
Originally Posted by dovercat /forum/post/18159256


As you are going to be calibrating the projectors, can you provide the calibration results.

So ideally you want dark dark scenes and bright bright scenes, high on/off contrast ratio is king. Ansi contrast ratio as long as it is high enough I would expect to be typically a non-issue as in a particularly image it is more likely to be image limited than projector limited. It is only important as a vague and unreliable indicator of projector mtf which will effect perceived image quality.

Keep in mind that I am going to be comparing the SAME projector at differing light conditions to itself, just as much as comparing the other projectors to each other. This nearly eliminates any error in calibrations. That said, I will calibrate because I know if I don't, the point I just made above will go past some people and I will hear people complaining that I did not calibrate. Again though, I am primarily comparing each projector to itself at differing light and taking measurements and noting what my eyes see at the varying light measurements and contrast ratios.


ON/OFF vs ANSI is somewhat subjective, but most experts claim that ON/OFF really only helps with black levels, but that's what I aim to prove or disprove. The problem with a lot of this stuff is engineers sometimes get too deep into the theory of it, well I want to compare the engineering numbers in direct correlation with what my eyes tell me. Ansi should make a large difference with POP in brighter scenes when viewing in a BAT CAVE (if what the experts say is true), but this is yet another thing I aim to prove or disprove (by seeing if my eyes can agree with the numbers).

TESTING METHODOLOGY

After much research, I have purchased an Eye One calibration device and a separate Spot light meter to take precise measurements. I will be taking contrast and light measurements from the light meter and the colorimeter. If this device does not convince me of its accuracy, I will have to move up to the Color Munki for $350. I could also go with a Spyder 3 Enhanced, but the Color Munki has a longer life and does not require a re-calibration as much, so that is why I would choose that one next over the Spyder 3. Now some people said the Eye One didn't do that well with projectors at lower lighting levels, but we shall see (again, I will exchange it for the Color Munki if I am not convinced, but I prefer not to spend $350 just yet).


Some people in here will snob the enthusiast as this is my first attempt with a colorimeter. Therefore in recogniziing my limitations, as a final test I will try to submit my resulting calibration graphs to an ICF expert calibrator and let him advise me on if the graphs look accurate enough.


In total, I will be running the projectors through an Eye One calibration device (or a ColorMunki), a separate dedicated light SPOT meter, a DVE disc, a Spears and Munsil Disc, some custom patterns from this forum, and another DISC. I will essentially look at all the results of what these calibration methods tell me and then throw out the ones that are the farthest off from an average, I will then average out the averages of what stayed within a relative deviation (in statistics I think this is called something like the confidence percentile method, where you throw out things that deviate above an X %).


I still have quite a bit of a learning curve to pull this test off properly.

 

[darinp2]

You could compare your estimates to what the contrast ratio estimator here:

http://home.roadrunner.com/~res18h39/contrast.htm


gives. And what this one gives:

http://home.roadrunner.com/~res18h39/intrascene.htm


That first one can be used pretty well to show how on/off CR, ANSI CR from a display, and room reflections that reduce ANSI CR affect images like a 10% checkerboard on black. The amount of image area covered by the checkerboard can also be reduced in that first calculator to simulate things like a small amount of white on black, or a small amount of 10% video level (which is less than 1% in ft-lamberts or nits) on black.


I ran some numbers from the first one in a section I called "Future Improvements" in an article I wrote in 2006 about contrast ratio that is here:

http://www.hometheaterhifi.com/volum...06-part-5.html


--Darin

 

[coderguy]

Darin,


Awesome, thanks for the info. I will read your article carefully. This is my first time attempting such a test, but hopefully I have done enough pre-research to do it accurately.

 

[sanderdvd]

This test never made it? I m curious about the importance of ANSI contrast in a complete 100% light controlled bat cave where everything is completely black (walls, ceiling, floor, furniture,speakers etc)

 

[DragonSixGolf]

Thanks for necroing this thread. I'm curious about results in environments with 100% light control where nothing is black. Tho i understand how ambition can sometimes exceed effort, so no worries OP.