Is this "DLP PROJECTOR RAINBOW TEST" reliable? - AVS Forum
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post #1 of 9 Old 07-17-2014, 10:20 AM - Thread Starter
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Is this "DLP PROJECTOR RAINBOW TEST" reliable?

Looking for information regarding the DLP Rainbow Effect, found this page in which there is a test, as the disclaimer in the page says:

Legal Disclaimer: This review contains statements of pure opinion and fair comments made in good faith in the interest of the public by AIM Digital Imaging. To ascertain the facts please do your own research. There are also quotes from and links to external sources please see their disclaimers.

this is the page´s link:

http://www.ausmedia.com.au/DLP_Sensitive.htm

And this is the test itself:

http://www.ausmedia.com.au/rainbow_test.htm


You can download the test to see it Full Screen.

For those who KNOW are Rainbow Effect Sensitive, would be nice if you check and see if this test shows what you are actually seeing with a DLP projector, this could be a starting point to those who don´t know if they are Rainbow Effect Sensitive.

And, if this is not a reliable way of testing it also would be useful to say it.

Your input would be usefull.

Thanks
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post #2 of 9 Old 07-17-2014, 10:42 AM
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The test doesn't show RBE (RainBow Effect). It is used to help people determine if they are RBE sensitive, and will help people determine that only when it is played back on a DLP projector.

I like the test, but it should be downloaded, and then when people are looking at projectors, they should bring a HDMI equipped laptop with them, along with that test, and plug it into a DLP projector. Both a 2x projector and a 6x projector should be tested (if possible) so that sensitivity can help be determined.

I will try to download the test and play it back on my W1070 to see how much impact it has on me. My PC operates (typically) at 1080p/60hz when I'm connected, so I expect that the color wheel will be operating at 4x speed. I expect to see some minor RBE issues, but I find that for extended viewing of typical content, I have only very minor RBE artifacts that I see and it doesn't give me headaches or cause nausea.

But, I like that test and am interested in how it looks and how well it presents RBE issues. It certainly is not what typical movie viewing is representative of, but will help those who have no idea what RBE issues look like, understand if they are RBE sensitive at all. If no issues are presented with a projector with a 2x color wheel (Optoma HD25-e or LV) then they should be pretty comfortable with almost any projector purchase.


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post #3 of 9 Old 07-17-2014, 04:46 PM
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Quote:
Originally Posted by tlalotoani View Post
Looking for information regarding the DLP Rainbow Effect, found this page in which there is a test, as the disclaimer in the page says:

Legal Disclaimer: This review contains statements of pure opinion and fair comments made in good faith in the interest of the public by AIM Digital Imaging. To ascertain the facts please do your own research. There are also quotes from and links to external sources please see their disclaimers.

this is the page´s link:

http://www.ausmedia.com.au/DLP_Sensitive.htm

And this is the test itself:

http://www.ausmedia.com.au/rainbow_test.htm


You can download the test to see it Full Screen.

For those who KNOW are Rainbow Effect Sensitive, would be nice if you check and see if this test shows what you are actually seeing with a DLP projector, this could be a starting point to those who don´t know if they are Rainbow Effect Sensitive.

And, if this is not a reliable way of testing it also would be useful to say it.

Your input would be usefull.

Thanks
I've just run this test through my projector (a W1070). I've been RBE-sensitive since the days of rear-projection DLP TV's, and I can attest that it's absolutely reliable.
Thanks for sharing!

It comprises of three consecutive, plain-white-on-plain-black (ie extremely high-contrast) tests; each, I found, more likely than the last to yield RBE. The first is relatively slow-moving, mainly-large objects; the second is much smaller, faster-moving objects; and the last is a single very-high-speed object (a pong-ball!) against a fixed high-contrast background.

It's a great test because it fully demonstrates the scenarios in which rainbows are most likely to present themselves; i.e., high-contrast scenes with fast-moving objects; especially if those objects are small. (Car headlights in the dark are a common real-world-video example of visible RBE that comes to mind).

We've noticed in the past (see here) that a DLP projector's color-wheel effective speed will often vary quite wildly according to refresh rate; so I ran this at three refresh rates for which the speed is known. It corroborates those color-wheel speed measurements.
  • At 24hz: I saw noticeable rainbows on every test.
  • At 60hz: The first test was clear; and I saw minor rainbows on the second test; and very noticeable rainbows on the third test.
  • At 50hz: Both the first and second tests were clear; and I saw minor rainbows on the third test.


In practice, I'd say the second test is the most realistic in terms of what a worst-case-scenario video will look like; and that's the one I'd recommend to get an idea of a viewer's real-world susceptibility to rainbows. The third test is unrealistic enough that it could probably elicit rainbows from a 20x color wheel - and as such, I'd ignore it unless you're planning on watching a lot of black-and-white films!


As a side-note, these tests also present that irritating engineering decision on BenQ's part to go with a rather slow speed at 24hz (the default framerate of a Bluray!) when they could have gone faster.

Still, at 50hz (which is what I now use for everything), in practice, the W1070 doesn't yield a significant amount of rainbows with regular video at all - at least not to me.

BenQ W1070 Projector; Xtreamer Ultra 2 (running XBMC on OpenELEC) via Sony STR-DH540 AVR with Boston Acoustics SoundWare XS SE 5.1 Audio. MediaBrowser3 for Mobile Streaming.

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Last edited by kreeturez; 07-17-2014 at 04:51 PM.
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post #4 of 9 Old 07-17-2014, 06:03 PM
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The test is a good tool, especially in the hands of knowledgeable testers of differing rbe sensitivity. The rest of the information on the site is a dangerous combination of ignorance and agenda. Using the test (realizing your options for refresh-rates and knowing how well it compares to actual film in motion) is helpful for anyone that can bring it to a store or try it on a PJ they can return.
The unrelated mentions of epilepsy and the guess about individuals susceptible to motion-sickness and similar ailments along with the ignorant wash statements about 3D, are probably best taken with a huge grain of salt..if not ignored completely.
It does make me curious if there has ever been any real testing for correlations between slow CW DLP discomfort and other visual-sensitive trouble or impairment.
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post #5 of 9 Old 07-17-2014, 06:12 PM
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Is this "DLP PROJECTOR RAINBOW TEST" reliable?

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Originally Posted by Ftoast View Post
The test is a good tool, especially in the hands of knowledgeable testers of differing rbe sensitivity.

The unrelated mentions of epilepsy and the guess about individuals susceptible to motion-sickness and similar ailments along with the ignorant wash statements about 3D, are probably best taken with a huge grain of salt..if not ignored completely.

Absolutely. Most of their HT projector stock is 3LCD, so that's clearly what they're punting.
Of course they fail to mention that, especially in the sub-$2000 price-bracket, 3LCD delivers exceptionally poor contrast, doesn't do well with motion, and is almost never truly sharp. Generally high input lag is another 3LCD concern that somehow doesn't get so much as a mention.

Indeed DLP is almost the only sane choice at present in that more accessible price bracket; and the fact that so few people are significantly affected by RBE in real-world viewing (which they do mention) means that it's a somewhat overblown concern; especially with faster color-wheels.

But the test itself is useful under the right circumstances, even if the site providing it isn't

BenQ W1070 Projector; Xtreamer Ultra 2 (running XBMC on OpenELEC) via Sony STR-DH540 AVR with Boston Acoustics SoundWare XS SE 5.1 Audio. MediaBrowser3 for Mobile Streaming.

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post #6 of 9 Old 07-17-2014, 11:41 PM
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This RBE test is stupid. If i have a DLP projector, and I'm perfectly happy with it, why would i run a test to help train my eyes to see RBE? I have a 3lcd projector, but i can't condone this. These guys clearly have an agenda. They do have some good info about contrast ratios, as for the rest, stay away.
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post #7 of 9 Old 07-18-2014, 03:42 AM
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Quote:
Originally Posted by ben38 View Post
This RBE test is stupid. If i have a DLP projector, and I'm perfectly happy with it, why would i run a test to help train my eyes to see RBE?
I guess one use-case would be for already-owners of DLP projectors - who are susceptible - to work out what refresh rate timings reduce RBE; if it's noticeable to them to begin with.

The other possibility is as AV mentioned above: purchasers of new projectors could use it to audition potential DLP candidates if they have a history of RBE sensitivity.
For instance at present, we have projectors that have relatively fast wheel-speeds of up to 5x (W1070); but by the same token, some on-the-market HT projectors are much, much slower (as low as 2x).
A potential buyer who favors a slower-wheeled DLP for other reasons (for its black level, throw distance, local availability, etc) would be wise to use a tool like this to double-check a slow wheel-speed won't be an issue for them if they have a history of RBE sensitivity.

Of course I limit all the above only to viewers with a history of RBE - and certainly not for use as an RBE-hunting expedition; since, like mentioned above, the vast majority of viewers don't notice anything to begin with.

BenQ W1070 Projector; Xtreamer Ultra 2 (running XBMC on OpenELEC) via Sony STR-DH540 AVR with Boston Acoustics SoundWare XS SE 5.1 Audio. MediaBrowser3 for Mobile Streaming.

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post #8 of 9 Old 07-18-2014, 05:09 AM
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I can see how this test can benefit the small percentage of people who are sensitive to RBE.

However, it's clear to me that this website is not concerned with the tiny percentage of people this tool might help. They want to use this tool to train the eyes of the other 99 percent to see rainbows so they can stop using DLP projectors altogether. They're very clear about this.
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post #9 of 9 Old 07-18-2014, 06:11 AM
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Yeah, whatever the merits of this test are, the website's purpose is to try to scare people into not buying inexpensive single-chip DLP projectors. Not surprisingly, their primary product is 3-chip LCDs. Funny thing is, for all of their rattling on about 4k and 8k, they don't appear to carry any 4k projectors.

Quote:
We strongly advise against using a single chip DLP projector (most models under $20,000) for the purpose of watching 3D content.

Especially for schools and public places etc. where a wide variation of sensitivities may be encountered some may be very sensitive to 2D content as well as 3D.

The simple reason is images are made by flashing colours; on top of that the L/R eyes are presented with alternating images.

3D watching comes with safety warnings, especially for children.

Systems trick you into seeing 3D and upset your natural 3D perception for a short time afterwards. (So don't go fly a plane).

And I find the following statement particularly amusing (more the 8k than the glasses-less 3d, which might come along in some form in a few years):

Quote:
The only "safe" way to watch 3D is without 3D glasses. Just as 8k UHD-TV will overtake 4k in a few years so will 3D that's "glasses free"
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Last edited by skater2; 07-18-2014 at 06:15 AM.
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