Which TV screen contrast is better, dynamic or static? Tips for the user. TVs Brightness high contrast and

One of the most important characteristics of a TV when choosing is the contrast value of the image on the TV screen. If you choose a TV based on picture quality, be sure to pay attention to the contrast value of different models.

A-priory contrast equals brightness ratio at the lightest point of the screen to the brightness of the point where the image is darkest. In other words, we divide the white level by the black level and get contrast. Only the values ​​of these levels can only be obtained through a special test of the TV using specialized instruments. Therefore, the average user has to trust either the manufacturers or various reviews on sites where TVs are tested. Who to trust more and how to check the contrast, and we’ll talk further.

We said that contrast is one of the most important characteristics of a TV. Therefore, manufacturers try to maximize this value to improve sales. The manufacturer can measure the brightness of a pixel in the laboratory when applying a signal that is never used in real conditions. Then measure the brightness of this pixel in the absence of a signal, which is impossible during normal viewing. After this, the contrast value is calculated. And the values ​​measured under such conditions are included in the product passport. Because of this, we see today that the contrast values ​​of many TVs are simply off the charts. All this is possible because there are no mandatory rules in the world for measuring the contrast of displays.

Separate static (natural) and dynamic contrast. Natural contrast depends only on the capabilities of the display, while dynamic contrast is obtained as a result of the use of additional technologies.

Static contrast is measured by the brightness of points in one scene (brightest and darkest). When measuring dynamic contrast, technologies are used to increase it. When playing a video, the TV itself adjusts the contrast depending on the scene currently shown on the screen. That is, the backlight in the LCD matrix is ​​adjusted. When showing a bright scene, the luminous flux from the backlight increases. And when the scene changes to dark (night, dark room, etc.), then the backlight begins to reduce its luminous flux. It turns out that on bright scenes, due to the increase in light from the backlight, the black level is poor, and on dark scenes, the black level is good, but the luminous flux will decrease. This is hard for us to notice because in bright scenes even backlit black appears completely black. And in dark scenes, the brightness of light objects seems sufficient. This is a feature of human vision.

This backlight control scheme increases contrast, although not as much as the manufacturers claim. And indeed, many TVs with dynamic contrast have superior image quality to devices that do not have such an adjustment scheme.

But still, displays with high natural contrast will be valued higher. This can be demonstrated by displaying a picture of white text on a black background. On a screen with high static contrast, the text will indeed be white and the background will be black. But a display with high dynamic contrast, if it shows a black background, then the letters will already be gray. Therefore, when playing regular video on a screen with increased natural contrast, the picture will be as close as possible to the real image. For example, there will be bright street lights against the evening sky. And against the background of a bright daytime sky, a black car will really be black. This is the image we see in cinemas.

As real as possible, in terms of contrast, the image was on CRT TV screens. But with the advent of the HDTV era, these television receivers gave up their place in the market to other devices. Today, high natural contrast values ​​are achieved using LCOS home projectors. The first place among these devices is occupied by JVC devices with their version of D-ILA. Next we can mention Sony with SXRD technology. In third place you can already put plasma TVs.

LCD TV manufacturers have introduced several technologies in recent years to achieve the level of contrast that is possible in other models. The best results in increasing contrast are achieved by using LED backlighting with local dimming. In this case, it is impossible to adjust the backlight of each pixel and each LED is not controlled individually, but the result is still good. But the producers abandoned the very effective type backlight, when LEDs are located over the entire screen area. Such production turned out to be expensive. Today, so-called side lighting is mainly used. Here the LEDs are located at the top and bottom. Local dimming schemes have also been developed for side lighting. TVs with such backlighting show enough good results by contrast value.

When choosing a TV in a store It is difficult to evaluate the quality of the display contrast. External bright lighting interferes; screens can have different coatings: anti-glare or glossy. The passport does not always contain the true contrast value, because manufacturers measure it in laboratories and by applying special signals to the screen. Even after reading several reviews on the Internet, it is not always clear what the real contrast value is. After all, everyone measures it in their own way.

Eat several contrast measurement techniques. First, a black field is fed to the input and the brightness is measured, and then a white field is applied and the brightness is measured. The result is good contrast, but during actual viewing there will never be a completely white or completely black picture. At the same time, when displaying a regular video signal on the TV, video processing is turned on, which also makes its own changes. More accurate readings are given by the ANSI test, when a checkerboard field with white and black fields is shown on the screen. This is more consistent with the normal image. But in this case, the white fields will affect the measurement of the brightness value of the black fields. So one correct method There is no contrast measurement.

So the recommendations for choosing a TV with good contrast remain the same. If you'll mostly be watching movies in a darkened room, then plasma is your best bet. In a well-lit room, an LCD TV with LED backlight due to its high brightness. Between these models you can put an LCD TV if there is a reserve in light output. And you need to remember the main thing, any TV needs correct setting. Adjust the brightness and contrast of the device correctly to obtain the highest quality image.

Additionally:

Image contrast describes the degree of contrast in a photograph. This is a dimensionless quantity, quantitatively expressed by the ratio of the brightness of the lightest area of ​​the image to the darkest.

Derived from the English Contrast ratio - a technical term used to determine the ratio between the strongest and weakest illumination of a reference screen when projecting white and black colors onto it.

Contrast– one of the main characteristics of the image, directly related to the brightness of the pixels.

As you increase the contrast of an image, the light areas (pixels) become lighter and the dark areas darker. As a result, pixels are redistributed due to the mid-tone range. Some of them turn into light, and some into shadow.

When the contrast of the image decreases, on the contrary, the mid-tone range expands due to the borderline highlights and shadows. Dark pixels become lighter, and light pixels become darker and partially transition into midtones.

A high-contrast image may contain no midtones at all. Conversely, a low-contrast image will have a predominantly gray color.

There are many images taken under unfavorable lighting conditions that have a faded, dull appearance. Such images need increased contrast.

Contrast shows how visually distinguishable certain areas (objects, items) of an image are. It directly affects the visibility of details and image clarity.

How to determine the contrast of an image

It should be noted that image contrast is a subjective value. Some people like contrasting images, while others like softer tones.

By analogy with optical contrast, which characterizes the distinguishability of an object from its surrounding background, the contrast of an image can be quantitatively defined as the ratio of the difference in brightness of light and dark areas to the light one.

K = (B 1 – B 2) / B 1

Here K is the contrast of the image, B 1 is the brightness of the lightest area, B 2 is the brightness of the darkest area.

The brightness of individual pixels in an image can be determined in Photoshop.

If K=1, we have absolute contrast. At K=0 there is no contrast. The image will be a gray background. Details will be indistinguishable.

True, this is only true for black and white images. They are characterized by bright contrast.

In a color image, objects that have the same brightness can be clearly distinguished due to color contrast.

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We continue to understand modern technologies and characteristics of televisions. IN we talked about characteristics such as screen type, diagonal and resolution. Now we will look at equally important characteristics of TVs: matrix response time, contrast, brightness, viewing angles.

Parameter matrix response time began to gain importance with the advent of televisions, the screen of which is a matrix. When choosing a plasma TV, you can ignore this indicator. Response time is measured in milliseconds (ms) and expresses the time it takes for a pixel to transition from one state to another (for example, going from white to black to white again). On average, the response time of LCD screens ranges from 2 to 10 ms.

The response time of the LCD/LED screen matrix becomes important when viewing dynamic scenes. In such cases, televisions with a long response time produce a “blurred” picture: trails of residual glow form behind fast-moving objects. To avoid spoiling your shopping experience, select the response time according to the purpose of using your TV. For watching movies and TV shows, a screen with a response time of 8-10 ms is suitable, but if you plan to connect a computer, limit the value to 5 ms.

CONTRAST

Under contrast It is customary to understand the ratio of the brightness of the light part of the TV screen to the dark part. For example, a value of 10,000:1 means that the white areas are 10,000 times brighter than the dark areas. Contrast level is determined by how saturated a dark color appears and how bright it appears White color. The higher the contrast, the more details and shades can be seen on the screen.

For high-quality video playback in HD format, the matrix’s own (static) contrast is not enough, so manufacturers have come up with a technology that allows them to increase this indicator. Modern TVs automatically adjust screen brightness based on frame content analysis. For low-light scenes, less backlight is emitted, giving more depth to dark colors; bright frames, on the contrary, become brighter.

This is where the concept arises dynamic contrast, i.e. contrast measured taking into account automatic brightness adjustments. LED backlighting of the matrix has significantly increased the contrast, so LED TVs have a clear and deep image (unlike ordinary LCDs).

BRIGHTNESS

In order for the eyes to be comfortable watching TV in any lighting (natural or artificial), the TV must have high brightness. Otherwise, watching TV will cause excessive strain on your eyesight and lead to fatigue.

The brightness index is measured in luminous intensity per square meter. (cd/m2). “Plasmas” have the highest brightness, this is obvious, because the technology of plasma TVs itself involves the self-luminescence of screen elements. LCD matrices have not yet reached such brightness levels, because the stream of light emanating from lamps or LED backlights must overcome a layer of not entirely transparent liquid crystals.

Typically, the brightness value of LCD and LED TVs lies in the range of 300-600 cd/m2, while the brightness of a plasma TV is 1000 cd/m2 and higher. But don't rush to conclusions! Too high brightness entails a loss of contrast (however, some unscrupulous manufacturers, for obvious reasons, prefer not to mention this). There must be a golden mean in everything.

To make it easier for you to choose the optimal combination of contrast and brightness, consider the following data:

• budget TV - brightness from 300 cd/m2, contrast from 1000:1;
• mid-price TV - brightness from 400 cd/m2 , contrast from 5000:1;
• expensive TV model - brightness from 600 cd/m2 , contrast from 20,000:1.

And yet, there is no such thing as too much brightness, especially since it can be easily adjusted. The only rule to follow is that you should not install your TV in front of windows, otherwise sunlight will ruin the whole experience.

VIEWING ANGLES

Viewing angle is the angle to the screen plane from which the image is visible without distortion. The characteristic became relevant with the advent of digital TV. Possible image distortions are associated with the structure of the LCD matrix itself. The fact is that the screen backlight (lamps or LEDs) is located at a very small, but still distance from the pixels of the matrix. Because of this, light enters the “gap” between the pixels and the lamps, limiting the scattering area.

In practice, this is expressed in the fact that as the viewing angle increases, we notice a decrease in brightness and contrast, and the picture quality gradually deteriorates. The most best picture we see while being perpendicular to the screen. Within +/- 60 o we observe an image of acceptable quality. Consequently, a picture without distortion is available at a viewing angle of approximately 120 o.

Expensive and thin TVs have a larger viewing angle (170-175 o). Budget models are characterized by values ​​of about 160-170 r. There's a little trick here: with proper installation, you can easily avoid "inappropriate" corners! Therefore, it is important to think about where you are going to install the TV.

For “plasma” this characteristic is not so important. A fundamentally different technology provides a large viewing angle (175-180 o).

Contrast

Contrast- in the most general sense, any significant or noticeable difference (for example, “Russia is a country of contrasts...”, “contrast of impressions,” “contrast of the taste of dumplings and the broth around them”), not necessarily measurable quantitatively.

Contrast- the degree of contrast, most often expressed quantitatively as a dimensionless quantity, ratio or logarithm of ratios.

Basic values

Quantitative characteristics

Contrast as a transfer characteristic

At quantitative measurement, unlike the previous group of meanings of the term, the ratio of the differences between two measured quantities, the output signal and the input, is used.

In the context of optical and photometric measurements, the term is used contrast ratio or contrast ratio. A similar parameter of the transfer characteristic in electronics is called AC gain.

• Reduced lens contrast- an integral characteristic that describes a decrease in the contrast of the image formed by the lens compared to the contrast of the optical object. Depends on lens aberrations, coating, lens processing, frame features, scene and lighting. Typically not standardized or described with an exact numerical value or graph.

Other meanings and terms

• Contrast (statistics)(English) en:Contrast (statistics)) - a linear combination of two or more average values. In the simplest case, it is the difference between two average values.
• Cold and hot shower- alternating change of water temperature from maximum cold to maximum hot and back.
• Language, or semantic contrast(English) en:Contrast (linguistics)) - opposition (English) opposition) between two parts of the argument.
• Contrast agent(English) en:Contrast medium) - a substance added during medical examinations (usually during radiography and fluoroscopy) to body fluids to obtain a more contrasting image of the organs being examined. For example, Barium Sulfate, Iodolipol.

Notes

• Photocinema technology: Encyclopedia / Chief editor E. A. Iofis. - M.: Soviet Encyclopedia, 1981. Articles:

Wikimedia Foundation. 2010.

See what “Contrast” is in other dictionaries:

CONTRAST, contrast, plural. no, female (book). distracted noun to contrasting; presence of contrast. Dictionary Ushakova. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary

CONTRAST, oh, oh; ten, tna. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

When talking about the contrast of a projector, first of all you should separate the contrast of the device itself and image contrast.

For example, to test a projector, I need to measure the contrast of the device itself, but when building a home theater, I need to know the contrast of the image, which consists not only of the contrast of the projector. In general, there are several ways to measure contrast, and the differences between them are not always obvious or intuitive.

What is contrast?

Another long introduction...

When talking about an image, contrast is the ratio of the brightness of white to the brightness of black.

To be pedantic, the “brightness” of the image (measured in foot-lamberts or nits) is measured from the screen, and there is also the luminous flux (lumens) or illuminance (lux), which is measured measuring device aimed at the projector.

All of these parameters can be used to determine contrast, but each has its own specifics, which will be discussed later.

The main thing for now is to understand the principle that we divide the “brightest” by the “darkest” - and get contrast. High contrast means high maximum brightness with "deep black levels". Low contrast is when blacks look like gray, but whites are not bright enough.

The peculiarities of our vision are such that there is a certain full range of brightness perceived by the eye with adaptation, and there is a range of brightness perceived without adaptation. For example, there is a story that pirates allegedly used an eye patch so that, upon breaking into the hold, they would have one eye already prepared for dark conditions. In other words, the eye is definitely not able to simultaneously cover the range of brightness that would include the darkness of the hold and the bright Caribbean sun on the deck - adaptation is required.

To create a contrasting scene at the projector, we, thank God, do not have to blind the viewer, although this is assumed by the HDR/UltraHD standards. For the familiar SDR, it is quite enough to repeat the brightness range that would be perceived by the eye as “contrast” without adaptation. It’s worth remembering here that SDR assumes that 100% white is the color against which you are currently reading this text, and not the blinding light of some spotlight or desert sun in the viewer’s face.

I briefly inquired about the sensitivity of the eye. There is an opinion that without adaptation the eye perceives, in the language of photographers, “from 10 to 14 stops,” which in theory should correspond to a contrast (the ratio of bright to dark) from 1024:1 to 16384:1 (though I don’t know in which ones exactly) conditions).

1024:1 is usually not a problem for an entry-level DLP projector for a home, but 16,000 and more is definitely the top segment, although it is far from the limit of the projector’s capabilities. In general, there is nothing outrageous about creating a contrasting picture.

But an important note right away. If I, as it were, propose to “prohibit the eye from using adaptation,” then let the projector’s specified contrast levels also be “fair” or “native.” The opposite of "native" is "dynamic" contrast, which is achieved using techniques such as automatic iris. In other words, we cannot see dynamic contrast in one image, but only sequentially - first on a dark, then on a white scene. And we should be able to see the “native” contrast on one stage.

Black depth

If we talk about contrast effects, then for starters we can separately mention the effect of brightness and black depth. It's clear that brightness is needed to make you believe you're on a sunny beach, or that the water is actually throwing reflections in your face. Especially high brightness is important in order to draw sunny weather...

The problem is that if there is a bright object, the eye will adjust to it and will be less picky about black. On a bright scene, even a “bad black” will look black, not only due to the adaptation of the eye, but also psychologically:

It turns out that we take two projectors with a contrast ratio of, for example, 2000:1. One will have deep blacks, the other will not, but will have extra brightness. That is, the level of black color should be discussed separately from contrast.

This suggests that the owner of an overly bright projector has two simple options: enjoy high brightness while sacrificing blacks, or reduce brightness, improving blacks. For classic HD content, there is a recommended image brightness, which in most cases is achieved at 1000 lumens or less (in the appropriate picture mode). If, let’s say, the projector produces 2000 lumens in the exact mode, and your screen size is 90 inches (that is, small), then you should probably worry about reducing the brightness. For budget projectors, one of the options is lamp mode (normal/eco), while top models have a lamp mode for this. manual setting aperture, or precise adjustment of the brightness of the light source - for “laser manufacturers”. If you are the owner of a budget projector and want to reduce the brightness, then you can look towards gray screens, or even try attaching an ND (neutral neutral) filter to the lens. However, I can’t give any exact recommendations.

ANSI contrast

Let's move on to measurements.

ANSI contrast measured from the projector screen, that is, we are talking specifically about his brightness. To measure contrast using the ANSI method, a test image is displayed on the screen in the form chessboard(black and white squares). This parameter is greatly influenced by a number of factors in addition to the projector’s capabilities:

• properties of the screen fabric;
• distance from the walls and room size;
• lack of background lighting;
• quality of darkening walls and ceilings, etc.

In this regard, it is important to understand that ANSI contrast is used to evaluate not the projector, but home theater, that is, a projector + screen + room system.

The first thing that catches your eye when trying to display a black and white checkerboard in an unprepared room is that the light from the white checkers, reflected from the ceiling, returns to the black checkers, significantly degrading the black level and contrast level. In most films, it is the simultaneous depth of black and the brightness of white that gives the picture realism and the immersive effect, creating an impression of volume and three-dimensionality in high-quality content. Therefore, ANSI contrast is exactly what you need to evaluate a home theater.

However, compare projectors Using ANSI contrast is difficult. If the author of the comparison is ready to guarantee that all measurement conditions will remain unchanged throughout the years during which he will make reviews, then (probably) you can take his word for it. However, one reviewer's ANSI contrast will be difficult to compare with another reviewer's ANSI contrast.

Why is this parameter so popular when testing projectors? The answer is that it completely eliminates the dynamic contrast factor. By measuring contrast using a checkerboard pattern, we don't give the projector any chance to engage the auto iris, which can increase contrast by 100 times or more, darkening blacks. Projectors with a laser light source, for example, allow the light to be turned off completely at any time, producing perfect blacks. But this will be useless when testing for ANSI contrast.

Full On/Off contrast (full on/off)

If ANSI is “simultaneous” contrast, then Full On/Off is “sequential”, that is, black and white measured one by one. This eliminates the influence of white on black and in almost any dark room we can quite accurately measure the brightness of black and determine the contrast the projector itself, if the measuring device is pointed at the projector (although there should not be a significant difference compared to measuring light reflected from the screen).

The key factor when using this method is whether the projector has automatic iris or similar methods of dynamic contrast enhancement (lamp, laser) activated. If they are turned on, then the black color may be 100 times darker or more, and we will measure dynamic contrast. If all this is turned off, then we get native(“fair”) contrast. In any case, we must be 100% sure whether "black enhancement" is used.

What contrast is indicated by the manufacturer?

Most likely dynamic. If it’s native, the numbers will seem too low. For example, when an expensive projector has a contrast ratio of 2000:1, then this is most likely the native contrast.

Dynamic aperture is useful if implemented well. It is also useful to the manufacturer because it allows any contrast to be specified in the specifications. As for, in fact, the correct operation of the diaphragm, there is a lot of uncertainty. For example, at what brightness does it start to work? Or will it turn on if there is a very small bright area on the screen? There are a lot of nuances, and the apertures of expensive projectors usually work more quietly and accurately.

The native contrast of the projector is highly dependent on the color rendering mode. The highest contrast ratio is usually achieved in the brightest mode, as color correction and calibration is inevitable reduce maximum brightness, but the black brightness remains the same.

Here's an example: in the bright mode, the white is slightly green, and to create an accurate mode for watching movies, we reduce the brightness of the green, which ultimately gives us the correct shade of white (neutral, colorless). As a result, the brightness of white decreased due to the loss of excess green, and the brightness of black remained the same (as much excess light as the projector matrix let through, so much does it let through). As a result, the mode seems to be intended for cinema, and the contrast turned out to be lower than in the bright mode, intended for a lit room.

Illuminated room

Rooms without prepared surfaces have a significant impact on the black level, but any external light simply kills it. In this regard, if there is possible flare in the room, the black produced by the projector itself (black depth) becomes less significant the brighter the light, and the maximum brightness becomes more significant. As a result, for office and school projectors, if they are operated in the light, everything turns upside down. The contrast of the projector is no longer important (since it is measured in the dark), but the brightness is important, which will increase the level of real ANSI contrast.

Sometimes contrast in such conditions refers to legibility (for example, text). The minimum contrast level that produces relative legibility is approximately 4:1, although an image with a contrast ratio of 7:1 or 10:1 can be considered adequate. For office projectors, color quality in the brightest modes is of particular importance, since poor color reproduction at maximum brightness may force the user to switch to a less bright mode, losing contrast/legibility.

It is worth noting that, despite the fact that black can be considered lost in illuminated rooms, this does not prevent you from creating a beautiful and colorful bright image with an emphasis on illuminated objects.

Screen influence

There are several ways the screen can affect black levels. Speaking about the most budget solutions, we are unlikely to go far from choosing between a regular matte and gray screen. The latter equally absorbs “white” and “black”, and therefore is only suitable for removing excess brightness. As a result, black becomes darker, and white... also darker. If the projector does not have very high contrast, then this may be a suitable option if you want to use it in a dark room.

The next level is reflective screens. Unlike conventional matte screens, which scatter light evenly in all directions, these screens also have a slight “mirror effect” or “glossy effect” in the sense that they reflect the light incident on the surface more directionally, according to the principle “the angle of incidence is equal to the angle reflections." Therefore, the viewing angle of these screens is lower, as is the uniformity of brightness. But they tend to reflect unwanted light falling from the side not at the viewer, but “somewhere else,” as a result of which the black level improves (especially in rooms that are not ideal from the point of view of a home theater). As a trade-off for this, spectators must be positioned in a narrower area.

At the forefront of technology are multi-layer ALR (Ambient Light Rejection) screens. They “eat up” side light more effectively, although they are significantly more expensive - this is clearly not a solution for a budget home theater. Typically, it's also about reflecting or absorbing light coming from the side and enhancing light coming from the side of the projector.

demonstration of the effect of ALR screen fabric CineGrey 5D

Gamma correction

Gamma correction is what happens to the brightness of the projector between black and white. In other words, the projector's response curve to the signal. For example, what percentage of maximum brightness will the projector output if it is commanded to “show 10% brightness”? Answer: not 10%.

In a lit room, a sharper increase in brightness is required for dark shades (shadows) so that they are distinguishable and do not merge. If you use a projector set for a lit room in a dark environment, the detail of dark objects will be overly emphasized and the image will be look low-contrast. In order for the picture to look contrasty and natural, gamma correction must be set correctly. You can read more about gamma.

Conclusion

I just wanted to say that the topic is extensive and this article will be updated. But that's all for now. Thank you for your attention!