Other Home Theatre

[#1]

I cannot provide the link because it goes against the forum policy, so I will copy and paste. Hope this answers all those burning questions abut contrast.

It has always been industry's favorite game - playing with numbers, and Contrast Ratio is one of the preferred names, with the latest craze in the video industry being the latest new mega contrast performance numbers.

The most recent figures for dynamic contrast range from 3,000,000:1 for LED TVs, 150,000:1 for standard CCFL-based LCDs, and 2,000,000 to 3,000,000:1 for the latest plasma HDTVs. When it comes to home theater projectors, the numbers are somewhat smaller but at 60,000:1, these still represent a huge step from the less than 1000:1 we were accustomed to a few years back! And the numbers are still growing...

Surely, we all love numbers - the bigger the better - but do these BIG contrast performance figures really mean something in the end?

PLAYING WITH CONTRAST FIGURES

Big numbers sell better, and manufactures know this very well. It applies to all areas in the manufacturing industry.

We have seen this number battle in the scanner and digital camera world when some manufactures got the insane idea of quoting the interpolated image resolution rather than the true optical resolution of the device. Surely a scanner with a 9600DPI or 19200DPI would seem better than one with 1200DPI  ...unless you know what you are really talking about.

The same applies to contrast ratio. It was Samsung that originally started boasting of unprecedented high contrast ratio ratings when it came out with the first flat-panel TVs with 4000:1 contrast rating. By 2007, figures for contrast ratio reached 15,000:1 and last year we have seen the first HDTVs with 50,000:1 for CCFL based LCDs and 1,000,000:1 for LED TVs and plasma HDTVs.

Now we are talking about multi-mega contrast ratios. It is as if there is no limit to how much these numbers can continue to grow. However...This contrast ratio issue is more complex than one may ever realize. Apart from the fact that TV makers do hardly specific whether they are referring to static or dynamic contrast - some HDTV manufactures are taking consumers for a ride by quoting unrealistic high figures for contrast resulting from unspecified testing methodologies. It is as if these TV makers are more interested at inflating the end figures to help sell their product over the competition than anything else.

What is Contrast: Defining and Measuring Contrast Ratio

Before continuing with our discussion on this subject, it is important to first have an understanding of what is contrast.

Contrast is the ratio between the white and black parts in an image. The larger the contrast ratio of a display device, the greater is the difference between the brightest whites and the darkest blacks a video display or projector can show. A contrast rating of say 300:1 would imply that the luminance for black level is 300 times darker than the white.

Static or Dynamic? Static contrast refers to a display device native contrast ratio. It is the more important of the two despite being smaller as it represents the 'true' contrast i.e. the darkest blacks and the brightest whites that a display can simultaneously support at any time.

Instead, dynamic contrast refers to the maximum ratio between the deepest blacks and the brightest whites that a display can show on its screen but not at the same time. A processor inside the display analyzes the picture content and adjusts the light levels on-the-fly to render deeper blacks and brighter whites. When done properly, dynamic contrast can help give the impression of higher contrast ratios, but done poorly, it can crush black to the point of losing shadow detail.

As expected, dynamic contrast ratios results in much larger numbers and is often the one most quoted by TV makers.

Note: Unfortunately, some definitions found on the web for contrast ratio would imply that an increased contrast ratio yields better subtle detail and increases the color palette. This is NOT true. An imaging device ability to display subtle detail arises out of its ability to display various levels or intensities of gray - often referred to as shades of gradation - from complete black to complete white i.e. it depends on its grayscale capabilities rather than out of a higher contrast ratio.

And with grayscale there also arise the issue of grayscale uniformity. This represents a device ability to maintain all shades of gray as close as possible the D65 (or 6,500K) standard across the entire range to preserve color fidelity at all luminance (brightness) levels. Many TVs fail here and instead tend to shift towards red in the darker areas and blue in the much lighter parts of an image.

MEASURING METHODOLOGIES

There are various measuring methodologies that can be used to determine the contrast performance of a display device. The two methods mostly used by the projection and video display industry are the Full On/Off, and the ANSI Contrast ratio measurement:

FULL ON/OFF: Full On/Off Contrast measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. This is the measurement most favored by manufactures as it yields a larger number for the contrast ratio - typically 25% more - than ANSI Contrast measurements for the same display device. What's more, some manufactures of DLP projection displays and projectors, would carry out this contrast ratio measurement with the 'white segment' of the color wheel turned on. This would increases the measured figures for the white, hence inflating further the end result.

ANSI: ANSI Contrast is measured with a pattern of 16 alternating black and white rectangles - also referred to as the 'checkerboard' test pattern. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio.

ANSI Contrast represents a more fair way to test contrast ratio as the presence of black and white at the same time is closer to the real world environment rather than  the all black or all white image used during the full ON/OFF contrast measurement. This renders the average reading obtained from the ANSI Contrast more realistic.

It goes without saying that when comparing the contrast ratings of home theater projectors and other video display devices, it is essential to make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same projector or monitor.

The unfortunate thing here is that there is nothing mandatory as to the methodology used by manufactures to measure contrast performance of their projectors or display devices. Even worse, manufacturers are not obliged to at least specify the method used to arrive at the quoted figures.

This renders a straightforward comparison of contrast performance figures between different imaging devices - especially from different manufactures - almost meaningless.

Don't be impressed with BIG Contrast Numbers!

MAKING THE DISPLAY: Contrast Ratio facts and numbers

There is no doubt that contrast is an important attribute in a display or video projector performance. It is contrast that helps make an image 'pop-up' in that it also affects our perception of color as well as image brightness. In fact, a minimum level of contrast is necessary for the eye to perceive an image as 'bright'.

The truth is that contrast cannot be taken on its own. A high contrast ratio can be misleading at best if used incorrectly; and in the promotional media, it can even turn out to be a lie.

A higher contrast ratio implies a device has greater ability to display black as 'black' instead of dark gray. This also means that a home theater projector with a contrast ratio rating of 10,000:1 is more capable of showing dark subject matter than one with a 1,000:1 contrast ratio. At the same time, it is important to realize that the difference in performance would only be apparent provided the projection is taking place in a completely darkened room i.e. one in which is there no light other than that generated by the video projector.

Equally important here is the fact that the eye would not detect a 10 times improvement in contrast performance - rather, the perceived difference in image performance between these two devices is marginal and detectable only if a room is in total darkness.

The complete absence of stray light in a room is a critical issue when it comes to contrast performance. In everyday life, this is an extremely rare situation unless viewing is taking place under a controlled environment, such as that of a dedicated home theater with black painted walls.

There is a very simple reason for this: Black can only be as black as the projection screen surface is in the ambient light present in the room.  Hence, if the room is not pitch dark, the screen surface will reflect some light - thus turning black into dark gray, and therefore reducing image contrast ratio.

Similarly, this applies also to direct-view systems such as plasmas and LCD TVs, in which case black is often nothing more than very dark gray, even though plasma and LED TVs (using local dimming technology), can manage to approach true black better.

LIGHT IN ROOM

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!

With this much light in the room, there is no difference between 500:1 and 10000:1 Contrast Ratio!

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). Why?

Just consider a 'low' 100:1 contrast ratio under 30 LUX of ambient light. Your projector would have to generate at least 3000 LUX for the brightest areas to maintain this minimal contrast. But to maintain this level of brightness over say a 100-inch diagonal 16:9 unity gain screen (30 square ft), you need a your projector with at least 8000 ANSI-Lumens output. In other words, your 2500 ANSI Lumens projector will never maintain its quoted 5000 or 10,000:1 contrast ratio even in a dimly lit room. (For more information on the issue of projector screens and video projector output, please refer to our article: Understanding projector screens.

It is therefore clear that unless you watch your moves in a completely darkened environment, it would be useless to stress too much and pay more for a device with a higher contrast ratio!

IMPORTANT FACTORS WORTH CONSIDERING
Contrast and Brightness: As already stated, contrast does not stand on its own! A higher image brightness level would yield a better perceived contrast ratio for a fixed level of ambient light.  This means that a projector with a lower contrast ratio but with higher rated lumens output - may under certain light conditions - perform better than one with a higher contrast ratio but lower brightness level.

Cinema: Interesting here is how professional digital cinema projectors perform. Present-day digital cinema projection equipment supports a typical contrast ratio of 1000:1; however, this varies according to make and model. For example, one of the world's most popular digital cinema projectors, the Christie CP2000 2K 3-chip DMD DLP Cinema™, despite its 35 trillion colors, has a contrast ratio rating of just 500:1 ANSI, 2000:1 full field.

A point of clarification: We are not discussing image resolution. The reference to the performance of digital cinema projectors applies only to contrast ratio. When it comes to image resolution, traditional 35mm and in particular 70mm movie film systems, support a far greater image detail than that supported by professional digital cinema equipment today.

Grayscale: One cannot talk about displays without mentioning something on the grayscale performance of a display or video projector. As indicated earlier on, grayscale represents a device ability to represent various luminance levels. The truth is that while contrast is an important attribute, yet contrast alone does not provide useful picture information - only the various levels of gray does.

It is the grayscale performance of an imaging device that is the single most important attribute to consider. A larger number of gray scales or shades of gradation would imply a device greater ability to display subtle detail in dark or bright scenes. It is also this element that enables a home theater projector or a video display to create a wide color palette. Without shades of gray, contrast alone is of no use in delivering image detail.

YOUR EYES ARE THE LIMITING FACTOR!

THE HUMAN EYE: An issue on its own!

The eye is not an absolute sensor. Unlike electronic sensors used in digital imaging systems - which are all absolute in their response, the eye has a dynamic response to contrast - also referred to as dynamic range. This in itself alters the whole equation in that what is really important is not some unrealistically high absolute ratio rating, but rather, how the end image is perceived by the eye. Why?

The eye is an extremely complex sensor with far greater response range than any film or digital imaging device. It is able to function both in bright sunlight as well as in very faint light during the night - that's a range of over 10 million to one! In photographic terms, that's about 23 1/2 stops.

At the same time, it is not possible for the eye to see the faint light from a star in the sky during the day. From a photographic perspective, this is like saying that a camera can operate over an extended range, but then the full operating range is achieved by adjusting the film ISO speed, the camera aperture setting, and even the exposure time.

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...

The eyes' ability to detect contrast depends on the scene brightness, with the contrast sensitivity of the eye decreasing to about 8% of its maximum at low light levels; the eye sensitivity also decreases with lower contrast subjects.

To complicate matters, the eye Contrast Sensitivity Function (CSF) is not linear - in as much as it decreases with a decrease in brightness, there is a brightness level above which the eye contrast sensitivity falls once again. It is estimated that the sensitivity of the eye is some 600 times less in bright sunlight.

At low light levels, the eye is able to integrate image information over a period of some 15 seconds to be able to see dimly lit subjects (it is like when you increase the camera exposure time to record subject information during low light level conditions).

However, moving from one brightness range to another would take time for the eye to adapt.  A 'dark-adapted' eye would be able to see a faint star in the sky, but this dark adoption process by the eye takes 30 minutes or so to complete - provided you haven't been exposed to bright sunlight during the day, otherwise, it may take even up to one hour for full adaptation to take place. Looking at a bright subject by a dark adapted eye would simply kill your night vision.

This implies:  The first 30 minutes or so during a movie are not the best in terms of contrast sensitivity. What's more, looking at a bright movie scene would not help when the next dark scene comes around!

And as if this is not enough, there are other factors as well that affect our contrast perception. For example, the eye would perceive a higher contrast when looking at static images than it would if it were to look at moving pictures even if these were to have similar contrast ratio to that of the static scene.

There is also the issue of the eye contrast sensitivity with spatial frequency.  Technically speaking, spatial frequency is the number of cycles subtended at the eye per degree of vision.

It can be thought of gaps between adjacent image parts that vary in contrast. There is a point above which increasing the spatial frequency i.e. decreasing the gap between adjacent image parts, will reduce the eyes sensitivity to contrast even though the contrast level of the image remains the same.

And what about the loss of contrast sensitivity with age? The amount of light reaching the eye photoreceptors diminishes as we grow older; this in turn affects the eyes' response to brightness and contrast perception.

Message Edited by Snapshot on 08-02-2009 08:08 PM

[#2]

Thank-you for this. This should be stickied and should be standard reading material for the home theatre forums.

[#3]

Excellent reading....

What about my signature....

[#4]

Thank you guys!

I just hope this will help those who have any questions regarding contrast...seems like a lot of companies rely on this to be a selling factor. Trust your senses...like Sonimax mentions in his signature...I totally agree.

[#5]

Here's a related article I found that may be a real eye opener to some buyers. I'm not posting this to criticize FS (this article refers to a different American store) or any specific make or model of TV, but to help consumers make an educated purchase. Most importantly, check out the "Tips" section!

It may be difficult to believe, but just a decade ago cathode ray tube-based TVs (CRTs) were the biggest sellers. CRTs have excellent viewing angles, outstanding black levels and high contrast ratios. The technology’s Achilles heel (aside from sheer bulk) was a lack of brightness compared to today’s flat screen sets. However, for most indoor viewing environments, the light output was adequate.

Not surprisingly, store lighting in the TV departments of major retailers like <store names omitted> a decade ago was subdued to better emulate home ambient lighting conditions so the sets wouldn’t look dim and washed out.

That’s hardly the case today, with store lighting levels purposely cranked up as much as 50 times typical home lighting conditions. Why the change? Because these intense levels can make the best displays with the blackest black levels and highest contrast levels look inferior to cheaper, lower performance displays. Not surprisingly, this leads consumers into buying the cheaper sets because they think they’re getting as good a set, if not a better one, for less.

Contrast, Brightness and Resolution

A TV’s native resolution, black level and brightness (called white level) controls its perceived image sharpness. Resolution of almost all HDTVs falls into two categories, 720p and 1080p, so from a static resolution standpoint, almost all large screen TVs today are about the same (either 720p or 1080p).

“Contrast ratio,” for example 1000:1 (or 1000 to 1) indicates how many times greater is the highest intensity white signal than the lowest intensity black one (the number 1 is the black signal). While that gives you a ratio it tells you neither how bright are the whites, nor how dark are the blacks.

Here is where stores utilize intense lighting to manipulate your judgment. In a typical home environment, the set that will appear to have a better picture and be seen as sharper will be the one with the blackest blacks and reasonably white whites (around 30 ft lamberts) rather than one that’s similarly bright but with lighter black levels.

Viewers perceive just the opposite in a high ambient light showroom. Invariably they choose the set with the brightest picture as having the clearest image, even if the set has poor black levels because the bright ambient lighting masks poor black level performance.

The Measurement Methodology

Last month, using a Konica Minolta T-10 illuminance meter, HD Guru measured the amount of ambient light in the TV sections of  national retail stores and warehouse clubs located around Long Island.

The measurement total depended upon the set quantity at each retailer; the more sets on display, the more measurements taken. See below for average reading per retailer. Daytime measurements in homeowners’ bedrooms, dens and living rooms also published below were taken with window shades and room lighting adjusted by the homeowners to their particular preferences. Not measured were kitchens, which tend to be far brighter than other rooms and where viewing time is limited and their smaller dimensions usually mean smaller screen sizes.

Store and Home Readings

Store averages (measured in lux) were: 411.66, 742.77, 371.38, 180.3, 412.13, and 236.58 <store names omitted>. By comparison, ambient light levels measured in 10 rooms of various homes ranged from just 1.2  to 110.1 lux, with all but two rooms reading less than 35 lux.

Why Do Stores Crank Up The Brightness?

Today, there are two basic retail categories: aided stores with salespeople, such as <store names omitted>, and unaided (self-service) ones like <store names omitted>. Price generally drives consumer purchases in unaided, brightly lit stores where the lower priced, poorer performing sets can appear to be as good as, or better than the more expensive sets. Get the set home and with no reference point, you’ll end up assuming you’re getting the level of performance observed in the store.

Management directs aided store salespeople to maximize profits. While there’s nothing inherently wrong with that, it does conflict with making the right HDTV choice. How? Let’s assume you have a budget of $1500.  HDTVs pricing is very competitive and store margins are low. Stores maximize profits by convincing you that a $1000 TV looks as good, if not better than the $1500 set placed next to it. That leaves you with $500 to purchase high profit margin items such as service contracts, “high speed” HDMI cables and power conditioners, when a perfectly adequate HDMI cable can be had on-line for under $10 and a relatively inexpensive surge protector is all you really need. Read this before buying a service contract: <link omitted>

Vizio TVs offer retailers lower profit margins compared to other brands according to industry sources. Not surprisingly, with the exception of (competitor), which is an aided store, Vizio’s retailers are unaided stores, where high lighting levels and Vizio’s low prices allow it to compete with and beat Sony and other established brands to win top sales positions.

The MHT Exception

<store name omitted> sells the best and most expensive HDTVs, including top of the line plasmas and LED backlit LCD flat panels not found on the main showroom floor.In order to demonstrate the best displays’ rich inky blacks, guess what <store name omitted> does? Correct! They match the store’s lighting  to about the same levels found in a typical home environment. Measurements taken at our local <store name omitted> measured from 24.4 to 49.2 lux with an average level of just 34.7 lux!  Yes, <store name omitted> understands that for its customers to see and appreciate the deep blacks, high contrast ratios and superior image quality produced by the more expensive sets it sells, it needs to duplicate home light levels.

Tips

Setting optimal black level for a given display requires adjusting user controls via the TVs remote control, with ambient lighting set to levels similar to what’s found in your similar level found in your home and specialized test signals.

Unfortunately, these conditions are not possible in the big box retailers and warehouse clubs listed above, so you’re stuck with the store’s showroom mode settings. However, you can get a relative idea of the black level of a given display regardless of the stores high ambient light levels by using this trick.  Cup your hands forming a tunnel with your thumbs and index fingers making the front opening. Place the pinky side of your cupped hands against the TV screen and place your eye against the front opening. You will need to find or black area of the picture, if you’re lucky, black bars will be present at the top and bottom of the screen on a letterboxed demo material. This will give you an idea of just how light the blacks are on different displays.

Contrast Ratios Specs Are Useless

No accepted TV industry standard exists for measuring contrast ratios. Numbers provided by manufacturers are meaningless. The fake spec race is getting worse with many vendors now providing two contrast ratio specs, standard and dynamic. “Standard” is with white and black areas on the screen at the same time. “Dynamic contrast” is measured using a black screen with no content, versus brightness with a white area on the screen, resulting in a useless number. Who cares how dark a blank screen looks? HD Guru continues to get stonewalled when we query set makers for the methodology of their respective published contrast ratio numbers. The current record absurd claim is a published dynamic contrast ratio spec of 7,000,000 to 1. To add to the confusion, there is a natural maximum eye contrast resolution of just 300:1, according to a paper published by Siemens Technology <link omitted>.

[#6]

Found another good article:

TV Contrast

Also called picture, contrast represents the total light output of the picture. Setting contrast too high will obscure fine details and if your TV is a CRT or a plasma it will shorten the lifespan.

Contrast is usually overdriven by factory defaults and purposely left too high in the store. Manufacturers reason that the TV with the highest light output will get the attention of shoppers. If you bring a new TV home you might notice contrast is set to 100%; this should be turned down to around 50%. At first, your eyes might miss that extra light from the picture but set the contrast properly against certain images and you'll see what you've been missing.

A contrast test pattern like this can be found on home theater tune-up DVDs like Avia.

Contrast test pattern sometimes found on DVD extras.

In lieu of a test pattern, an image like the one below showing fine details between black and white will suffice. Pause a suitable image on a DVD, turn the color control all the way down so you only see grayscale (black and white). Now you're ready to begin setting contrast.

Delicate details in sand can be used to find perfect contrast.

Start setting contrast by turning the contrast down until the picture looks too dark. Bring contrast back up slowly.You'll notice there is a point where the fine lines between black and white become blurred - this is where contrast is too high. Once this is set correctly, more detail will emerge. Explosions, flame, ice, snow, wrinkles in a shirt all contain details that get glossed over when contrast is too high.

If your TV is older and you find that you cannot set the contrast high enough, this could be a sign that your TV has outlived the picture tube. If your TV's contrast control has an obvious limited range and isn't able to get bright enough, it's time to get it serviced or replaced. After about ten years of steady use a CRT is sure to lose some of its picture.

Message Edited by Snapshot on 08-22-2009 09:13 PM

[#7]

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Evan_H wrote:

Contrast Ratios Specs Are Useless

No accepted TV industry standard exists for measuring contrast ratios. Numbers provided by manufacturers are meaningless. The fake spec race is getting worse with many vendors now providing two contrast ratio specs, standard and dynamic. “Standard” is with white and black areas on the screen at the same time. “Dynamic contrast” is measured using a black screen with no content, versus brightness with a white area on the screen, resulting in a useless number. Who cares how dark a blank screen looks? HD Guru continues to get stonewalled when we query set makers for the methodology of their respective published contrast ratio numbers. The current record absurd claim is a published dynamic contrast ratio spec of 7,000,000 to 1. To add to the confusion, there is a natural maximum eye contrast resolution of just 300:1, according to a paper published by Siemens Technology <link omitted>.

---

I couldn't say it better....

BTW, LG is announcing LCD tv's with a 7,000,000 to 1 CR.

[#8]

A 7,000,000 to 1 contrast rating? Oh my...that's pretty impressive and how will it look beside a 20000:1 CR TV?...perhaps in my livingroom, probably very close. We can only see so much with our eyes regardless whether you wear corrective lenses or don't, what do these companies take us for?...some they take for suckers. Let's increease the contrast to 7,000,000:1 and jack the price $500 or $1000 more. Great! Now we have this super-contrast TV which looks just as good as our 20000:1 and 50000:1 TVs...well done LG.

Was just looking for contrast comparisons on the site here and noticed they only have Dynamic Contrast numbers, no Static numbers available. That's interesting...  

[#9]

Here's an interesting site I found:

http://www.clarkvision.com/imagedetail/eye-resolution.html

Here's some interesting points: 

- 74 megapixels to show detail at the limits of human visual acuity

- The eye is not a single frame snapshot camera. It is more like a video stream

- 576 megapixels - the full angle of human vision would require even more megapixels. This kind of image detail requires a large format camera to record.

- Its estimated that the dark adapted eye is to be about ISO 800

- The 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 range of the human eye is greater than any film or consumer digital camera.

- Aperture for human eye is f/3.5 when dark adapted

- Maximum aperture of 7mm, this implies about a 25mm focal length

Message Edited by Snapshot on 10-05-2009 10:19 PM

[#10]

From another site that I cannot mention.  

The Human Eye

The human eye, at any particular instant, can perceive contrast ratio over a range of 400:1 to 10,000:1 according to numerous references. However, the human eye is a dynamic organ and can adjust, both chemically and via iris movement, over some 30 minutes in steady light conditions to perceive higher contrast ratios of up to between 1,000,000:1and 10,000,000:1. One can think of the eye as an adaptive detector. Age is a factor influencing what contrast ratio might be perceived by the particular individual.

The images displayed can affect the perceived contrast ratio with the human eye being able to detect higher contrast ratios for static images as opposed to moving images.

Ambient Light Conditions

Even small amounts of ambient light (one LUX – a candle flame) significantly reduces the ability of display devices to render higher contrast ratios (in the 1,000’s). A black area can only be as black as whatever incident light is reflecting from it. You cannot “project” the color black. Doubly detrimental is the rapid drop off of the eyes contrast sensitivity with higher ambient light levels.

Spatial Frequency

The eye is sensitive to the spatial frequency which is a factor related to the distance between the contrasting image elements in relation to each degree of field of vision at the eye. Consider that the frequency is the count of the number of alternating vertical stripes of black and white across an arc of one degree with the eye as its origin. Increasing the number of vertical stripes across the arc (making them thinner) will, beyond a certain point, reduce the eyes ability to perceive contrast ratio – even though the actual contrast between the white and black stripes remains the same.

CONCLUSION

Differences in contrast ratios in the multi-thousands should only be a consideration in choosing between display devices when you are going to place them in a strictly controlled, very low ambient light environment – something like a windowless home theatre room with dark finishes on all walls and surfaces.

For higher ambient light viewing environments brightness should be a much higher rated selection criteria than contrast ratio.

There is no substitute for judging between the image quality of displays than viewing them side by side with your own eyes in a viewing environment with an ambient light level similar to where they would be located. (Is this not in Sonimaxs' signature?)

Message Edited by Snapshot on 10-05-2009 10:18 PM