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Why You Should Ignore Contrast Ratio Specs:

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Old 01-08-2009, 05:01 AM   #31  
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I came across this while checking out specs on a set I'm thinking of buying. On the left there is a video that explains things pretty well. At least I think so anyway.
http://www.crutchfield.com/App/Produ...S4100&g=146350
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Old 04-02-2009, 12:33 PM   #32  
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yeah, I'm going to go ahead an disagree with the original poster on this topic. I witnessed first hand the difference in contrast ratios, and now I swear by them.
I bought a 42" Samsung plasma tv with a 1000: ratio. The images were awful! They were smudged to the point where I could not bear to watch.
I then returned it for a 42" Panasonic plasma tv with a 5000:1 ratio. Wow, what a difference. Each picture was sharp.

Now, I don't claim to be an expert on TVs, or even the techie side of it, but this was just my personal experience.
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Old 04-02-2009, 02:25 PM   #33  
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They are not totally baseless in what they quote in the spec, but they are grossly exaggerated to varying degrees for each mfg/model so you need to eyeball them which IS the point of the original post.

Each year they seem to improve the true CR so this is likely what you saw.
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Old 04-06-2009, 08:13 PM   #34  
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oh well, guess 1,000,000:1 Contrast Ratio doesn't matter lol
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Old 08-11-2009, 01:17 AM   #35  
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The Contrast Ratio Game

http://www.practical-home-theater-gu...ast-ratio.html
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Old 08-11-2009, 01:29 AM   #36  
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Great article Lee. Thanks!
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Old 08-11-2009, 01:35 AM   #37  
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Quote:
Originally Posted by PFC5 View Post
Great article Lee. Thanks!
My pleasure.

Hope people read it!
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Old 08-12-2009, 02:14 PM   #38  
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Quote:
Originally Posted by Lee Stewart View Post
Yes, great article and an excellent addition to this thread.

I would like to make two comments however:

In the section with the candle:


The authors make the following observations:
Quote:
Presence of light: To better understand the impact of the presence of light in a room on the contrast ratio performance of an imaging device, it is sufficient to realize that with the light emitted by just one candle in a room - that's just one LUX - there would not be any difference between a 1000:1 and a 5000 or even a 10,000:1 contrast ratio!

Assume that instead of pitch darkness, you have say 30 LUX of light in a room. This corresponds to just less than the typical level of natural light you would get in a room during the day without direct sunlight.

With just 30 LUX, contrast ratio figures above 100:1 would turn out to be simply academic even in the case of video projectors with relatively high brightness ratings (2000/2500 Lumens and above).
It's important to note (and can be found within the text) that this applies in the case of projection devices and reflective screens. Obviously a small amount of light reflected off of a white or silver screen is going to make a big difference and, I have always guessed, a much bigger difference than a flat panel television.

I have been familiar with the source of that photo and data for quite some time, but decided not to put it in my original post to this thread because I did not think it was directly applicable to flat screen tvs and I did not wish to present any information that could not be cited from a reliable source or that might mislead.

Search though I may, I have never been able to find a source that has made the same tests regarding flat panels.
I suspect that with matte panels the amounts of lighting discussed here (1 lux to 30 lux) might have very little significance.

Regarding the section on the human eye:
Quote:
It is the same with the eye; at any given instant, the eye can possibly see over a range of 400 to 800:1 in contrast detection. Here, there is a whole debate about this with some saying this is 100:1, others say 1000:1, and some even mention 10,000:1. As soon as the eye moves (saccades), it re-adjusts its exposure both chemically and by adjusting the iris. Over time, it is possible for the eye to resolve a contrast ratio range of between 1,000,000 and 10,000,000:1, but...
Although, as the author points out, the "debate" continues regarding the highlighted section above, every source that I have been able to locate confirms that about the best the human eye can perceive without re-adjusting is on the order of 750:1.
And, the re-adjusting is slow compared to the dynamic content of programming.

IMHO, people should be aware of this when considering whether or not they wish to be "awed" by the manufacturer's claims and specifications.

Again, great post, thanks.

Last edited by Scottnot; 08-12-2009 at 02:24 PM..
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Old 08-12-2009, 02:30 PM   #39  
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The Dynamic Range of the Eye

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The Human eye is able to function in bright sunlight and view faint starlight, a range of more than 10 million to one. But this is like saying a camera can function over a similar range by adjusting the ISO speed, aperture and exposure time.

In any one view, the eye eye can see over a 10,000 range in contrast detection, but it depends on the scene brightness, with the range decreasing with lower contrast targets. The eye is a contrast detector, not an absolute detector like the sensor in a digital camera, thus the distinction. (See Figure 2.6 in Clark, 1990; Blackwell, 1946, and references therein). The range of the human eye is greater than any film or consumer digital camera.

Here is a simple experiment you can do. Go out with a star chart on a clear night with a full moon. Wait a few minutes for your eyes to adjust. Now find the faintest stars you can detect when the you can see the full moon in your field of view. Try and limit the moon and stars to within about 45 degrees of straight up (the zenith). If you have clear skies away from city lights, you will probably be able to see magnitude 3 stars. The full moon has a stellar magnitude of -12.5. If you can see magnitude 2.5 stars, the magnitude range you are seeing is 15. Every 5 magnitudes is a factor of 100, so 15 is 100 * 100 * 100 = 1,000,000. Thus, the dynamic range in this relatively low light condition is about 1 million to one, perhaps higher!
http://www.clarkvision.com/imagedeta...esolution.html
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Old 08-12-2009, 02:37 PM   #40  
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The human eye can be tricked into seeing dark gray as black when most of the screen is very bright, and only a little black. I see this when I watch a movie and the black elements of the picture are only a small part of the picture surrounded by bright elements. I know it is my eye being tricked since when I look at the black bars right next to the black bezel of the screen I can clearly see the black is really only dark gray. That shows to me that what the human eye can see as contrast ratios is relative to not only what is on the screen but also the room lighting even with flat panels.

This is WHY I believe black levels (often confused with contrast ratios) is so important. One aspect of the LCD contrast ratios claimed is based on it being in torch mode which does make the whites brighter, but at the expense of black levels. Once adjusted for typical home lighting we end up turning the brightness (but more so the back lighting) down more to keep from burning our eyes out in a dimly lit room. I do see the same thing with plasma also, so this is part of how the human eyes work and their limitation. True contrast ratios are higher with plasma because of the usually deeper black levels once in that dimly lit room where the brightness would have to be turned down anyway and takes a major pro of LCD out of the equation.

The best way to compare HDTVs in a store is to find a store (hard to find) that has the displays in dim lighting similar to what is in the home viewing environment it will be watched in.
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Old 08-12-2009, 02:44 PM   #41  
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Quote:
Originally Posted by PFC5 View Post
The human eye can be tricked into seeing dark gray as black when most of the screen is very bright, and only a little black. I see this when I watch a movie and the black elements of the picture are only a small part of the picture surrounded by bright elements. I know it is my eye being tricked since when I look at the black bars right next to the black bezel of the screen I can clearly see the black is really only dark gray. That shows to me that what the human eye can see as contrast ratios is relative to not only what is on the screen but also the room lighting even with flat panels.

This is WHY I believe black levels (often confused with contrast ratios) is so important. One aspect of the LCD contrast ratios claimed is based on it being in torch mode which does make the whites brighter, but at the expense of black levels. Once adjusted for typical home lighting we end up turning the brightness (but more so the back lighting) down more to keep from burning our eyes out in a dimly lit room. I do see the same thing with plasma also, so this is part of how the human eyes work and their limitation. True contrast ratios are higher with plasma because of the usually deeper black levels once in that dimly lit room where the brightness would have to be turned down anyway and takes a major pro of LCD out of the equation.

The best way to compare HDTVs in a store is to find a store (hard to find) that has the displays in dim lighting similar to what is in the home viewing environment it will be watched in.
That is the whole crux of the issue. In bright scenes the contrast ratio takes a nose dive. It is only in low light scenes does the CR soar to high numbers.

But we are still limited by the 8/24 bit makeup of the signal which only results in a gray scale of 256 steps between total black and total white.
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Old 09-21-2009, 03:16 AM   #42  
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Old 10-24-2009, 11:05 PM   #43  
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Of course the contrast ratios are exaggerated and it would be hard to measure between brands. However if you take a Sony tv for example, with 1000:1 contrast and compare it to a Sony Tv with 100,000:1 contrast you will most definitely see a difference in black and white levels. While the actual numbers may not accurately represent the difference in those levels, there is still a significant enough difference to see with the human eye. Therefore, no you cannot take contrast ratios at face value but you should take it into consideration while choosing your set and it should not be ignored.
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Old 10-25-2009, 10:30 PM   #44  
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Quote:
Originally Posted by tom1088 View Post
Of course the contrast ratios are exaggerated and it would be hard to measure between brands. However if you take a Sony tv for example, with 1000:1 contrast and compare it to a Sony Tv with 100,000:1 contrast you will most definitely see a difference in black and white levels. While the actual numbers may not accurately represent the difference in those levels, there is still a significant enough difference to see with the human eye. Therefore, no you cannot take contrast ratios at face value but you should take it into consideration while choosing your set and it should not be ignored.
In theory that sounds good, but unless you KNOW that each model was measured that exact same way under the exact same conditions, then they still mean nothing. Especially when comparing different model years even from the same brand. CR ratios have steadily improved each year but nothing close to how much higher they have increased the spec numbers each year. They are all fudging them to gargantuan proportions and how much is from changing methods to get those numbers are unknown so they all must be thrown out the window and objective and independent ratio measurements need to be used and also after calibrating our own eyes with the exact same content as a comparison, under the exact same lighting conditions.
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Old 10-26-2009, 08:24 PM   #45  
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Quote:
Originally Posted by jmcohen23 View Post
yeah, I'm going to go ahead an disagree with the original poster on this topic. I witnessed first hand the difference in contrast ratios, and now I swear by them.
I bought a 42" Samsung plasma tv with a 1000: ratio. The images were awful! They were smudged to the point where I could not bear to watch.
I then returned it for a 42" Panasonic plasma tv with a 5000:1 ratio. Wow, what a difference. Each picture was sharp.

Now, I don't claim to be an expert on TVs, or even the techie side of it, but this was just my personal experience.
I think your jumping the gun here, how do you know for a fact the contrast ratio had anything to do with the picture quality differences? It could have been a defective set, but to jump to conclusions... Panasonic does make a better plasma, you'll get no argument from me there!
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