Parameters of modern LCD monitors. Which monitor to choose for your eyes? What to look for? Setting and assessing image quality

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In this article we will deal with the question of how to choose the brightness of the TV screen. Basically, the brightness of your TV screen depends on the settings on your TV. So, let's focus on the basic provisions of the settings: what, how, where, why, why and what will come of it.

The first thing to note is that most TVs have two brightness settings: backlight intensity (the brightness of the screen as a whole) and signal brightness. TV brightness is, simply put, an adjustment of the black level in the signal. And if we speak in the language of scientists, then brightness (again, simplified) is the ratio of the intensity of light to the area of \u200b\u200bthe luminous surface. Modern TVs have a screen brightness of 400-500 or more candelas per square meter. Perhaps the only usefulness of excessive brightness is noticed only when watching 3D films, and even then in shutter glasses, since even when open, liquid crystal shutters absorb a decent amount of light.

What does backlight brightness mean? Let's assume that you have adjusted the screen brightness to suit you, considering it the most optimal, but something still creates discomfort, for example, excessive brightness in the evenings or when the lights are off. To adjust the brightness of your LCD TV, find the “Backlight” or “Backlight Brightness” item in the settings menu. If the menu is in English, look for the “Backlight” item. Changing the screen brightness using the menu settings changes the overall brightness of the screen itself without affecting the signal brightness settings. In fact, there are no adjustment rules - you are your own boss and you adjust the screen brightness for your own viewing convenience. The most important thing when adjusting screen brightness is not to overdo it. If this is your first LCD TV, then most likely the bright and contrasting image may seem very pleasant and convenient to you, but over time it will create discomfort, at least for the eyes, which will cause increased fatigue. Also, a lot depends on the actual, real contrast of the TV. If your TV has decent anti-glare and good black depth, then the image will look quite vibrant, deep and bright even with minimal brightness settings. But you should understand that you won’t be able to jump higher than the capabilities of the TV itself. So, the characteristics of the TV itself play a big role.

Here are some facts and tips to become more enlightened about screen brightness: Most LCD TVs come with increased brightness. If there is a lot of lighting in the room, it makes sense to leave high brightness, and vice versa, in the dark it makes sense to reduce the brightness (as with laptops or smartphones, there is no universal brightness value, you constantly change the backlight level), lowering the brightness also reduces the load on eyes. And remember that moderate brightness provides better perception of the image on the screen.

Adjusting TV brightness

Very often, when adjusting brightness, you cannot do without contrast. In fact, calling contrast contrast is a mistake, since contrast is the ratio of the maximum brightness of the white level to the black level, and if we adjust the contrast on a TV, we actually only change the white level, and, accordingly, the maximum brightness of the image.

Here are some tips for adjusting the contrast of plasma TVs:

It is best to adjust contrast in the dark
Set the contrast parameter close to maximum (90-95, for example)
Reduce the “contrast” parameter until the picture with a white level (100IRE) stops putting pressure on your eyes and is perceived comfortably

By the way, Samsung plasma TVs have such a parameter as “cell brightness” in the English menu “cell light”. It has a big impact on the overall brightness of the image. Try setting it to a value close to the maximum (18-20), and follow the tips described above.

With LCD and LED TVs the story is similar, but nevertheless different. They contain a parameter called “backlight brightness” (sometimes there is “backlight contrast”). It plays a decisive role in creating the overall brightness level of the image. And again tips:

Perform setup in the dark
Set the contrast setting closer to maximum (90-95)
Display image with white level window (100IRE)
Set the backlight brightness to maximum or very close to maximum
Next, reduce this parameter until your eyes perceive the image on the screen normally without feeling discomfort.

It is also highly undesirable to set the contrast parameter to the maximum value, since some TV models may experience difficulties with such parameters and non-linearities in color temperature may occur. And, most importantly, do not attach too much importance to the brightness and contrast of the image. Overdoing the adjustment can negatively affect the level of fatigue of your eyes and their condition in general.

Also, to obtain the highest quality image on your TV screen, it would not hurt to pay attention to parameters such as “color” and “saturation”. However, there are no rules for setting up here either; we can only provide recommendations. Without measurements, it is extremely difficult and almost impossible to establish this parameter. The most optimal solution regarding the brightness of the TV is to display high-quality photographs and pictures of nature on the TV screen (give preference to the green color, since it is the green color that our eyes are most sensitive to, and besides, green very often looks unnatural on TV screens). After that, simply adjust the “color” and “saturation” parameters until the image seems most realistic and “alive” to you. You can also test these settings on high-quality photographs of people, adjusting the settings until the skin tone becomes a natural color.

Well, when asking questions about what brightness of a TV is better, what the brightness of a TV should be, or what brightness is optimal for a TV, it is impossible to answer unequivocally. You yourself can adjust the brightness of your screen to suit your customs and tastes. We hope that this article will help you in this simple matter. Good luck with your purchases and settings with !

This review is an addition to the article about the monitor.

Brightness and contrast are important criteria when choosing a monitor. Perhaps this is one of the few moments in choosing technology when it makes at least some sense to rely on hard numbers.

Brightness is measured in candelas per square meter. This phrase doesn't mean anything to 99% of users, so we'll tell you a little about it. A 100-watt incandescent light bulb has a brightness of about 100 candelas. Don't think that 1 watt = 1 candela, it's just a coincidence. An ordinary candle shines with a brightness of 1 candela. This is the second name for candela - candle, which is no longer used.

Many readers have wondered why brightness is measured in candelas per square meter rather than just candelas. The fact is that if you measure brightness in conventional units, then the larger the screen diagonal size, the higher the brightness will be. The consumer is primarily interested in how intensely each point of the screen will shine.

If the monitor's brightness is 250 candelas per square meter, then calculating the absolute value is not difficult. For example, a 23-inch diagonal monitor has a surface area of about 0.2 square meters. That is, in total it will emit 75 candelas of light. This is a very worthy value.

It is believed that to work with office applications, a brightness of 70-110 cd/m2 is required, which can be provided by almost any modern LCD monitor. Watching videos and playing games often requires high values, especially if the game involves you wandering around a dungeon and it's dark.

In the age of CRT monitors, many users suffered in such situations. Monitors based on a cathode ray tube could not achieve high brightness, since the capabilities of the phosphor coating were limited. In addition, CRT monitors burned out quickly. It's a thing of the past now.

With contrast, everything is much more complicated. Contrast refers to the ratio of the luminosity of a white pixel to a black pixel. Of course, a black pixel cannot glow, so the name “black” itself is very arbitrary.

An LCD monitor cannot produce black at all. For example, CRT displays could do this, since the light there was emitted by a phosphor coating under the influence of a flow of electrons. No electrons means no light, which means you see black.

In LCD monitors, light is emitted by diodes or lamps, and the matrix only controls its level. Liquid crystals are not able to block light completely, so there is no true black in LCD displays. Contrast is the ratio of pixel luminosity in white and black states. 1000:1 means that a white pixel on the screen is 1000 times brighter than a black pixel.

Manufacturers themselves do not measure contrast, they save money that way. They simply copy the passport data of the matrix into their passports. Of course, such a “hacky” approach does not apply to professional models from NEC.

It is not difficult to see such effects. Just take the PAINT editor that comes with any version of the Windows operating system and draw a big black square. Look at it and turn off the monitor. If you see a difference, then this monitor has a contrast problem.

It is worth noting that with modern models the difference between true black and backlit black is difficult to notice in room lighting. If you set out to test this theory, then it is better to experiment in the evening without light or with the curtains drawn.

A serious difference between the passport and real contrast lies in the desire of manufacturers to put as large numbers as possible in the monitor passports. They rewrite them from matrix manufacturers, because they understand perfectly well that the real values will be lower.

At matrix production factories, during testing, maximum electric field voltages are always applied to liquid crystals, whereas in reality, monitor electronics may perform worse. You shouldn't compare expensive laboratory equipment with $200 displays.

Conclusions. Don't trust the numbers in your passports. Brightness can be easily assessed by eye. While in the store, just “turn up” the brightness to maximum and you will understand what this or that display is capable of. Checking the contrast is much more difficult. You can also try to “turn up” the contrast to the maximum and look at some very colorful picture.

Knowing the characteristics of a TV can be useful when choosing in a store or when setting up. Some people think that choosing a TV receiver is best based on price. But if you look at nearby turned on devices of different series and manufacturers, you can see differences in picture quality. Of course, if they turn on only one TV and put on the desired content, then it’s hard to notice the shortcomings. Therefore, you need to know the characteristics of TVs and how to evaluate them.

1. Brightness. This is one of the most important characteristics of a TV. Any type of display requires a margin of image brightness. Then it will be comfortable to watch the television receiver at any level of external illumination (daylight, bright electric light, etc.).
The minimum value is 350-400 cd/m², while normal picture quality will be maintained. As the screen diagonal increases, the brightness indicator in the TV passport also increases. If for 19-inch TVs the brightness can be 250 cd/m², then for 36-inch TVs the brightness is already from 500 cd/m².

To check the brightness, when broadcasting a story with normal lighting (for example, news), turn the brightness value on the TV first to minimum and then to maximum. At minimum, the picture should darken noticeably to the eye, but in LCD models there may not be a noticeable darkening. The main thing is that the image should be with a brightness no greater than normal, the eyes should not hurt when viewing (especially relevant for LED backlighting). And at maximum, the image should lighten, also noticeable to the eye.

2. Viewing angle. This characteristic is not as relevant today as it was several years ago. Indeed, unlike CRT TVs, LCD matrices have image quality that depends on the viewing angle. And in early models it was impossible to watch LCD TV from the side. But even today you should still check the quality of the picture when viewing from different angles. To check, you need to step away from the screen and check the image quality, if it satisfies you, then everything is fine.

In the passport, viewing angle values are expressed in degrees. A normal value would be above 175 degrees vertically and horizontally.

3. Connectivity. Look at what you are going to connect to your TV. Do you have enough connectors and where are they located? Today you can connect: a Blu-ray disc player, a video camera, a camera, a game console, a computer, an external USB drive (flash drive), a home theater, headphones, an antenna, a satellite receiver, etc. This means that the TV must have the necessary connectors. These can be tulips, SCART, S-Video, component, HDMI, DVI, USB, etc. USB connectors (at least 3 pcs.) and HDMI 2.0 are relevant today
More details about.
4. Pixels. The characteristics of the TV also include the number of dead pixels. These are pixels that do not operate under the control of an incoming signal and glow in one color. If you look closely at the screen, you can find such pixels. Manufacturers allow in the characteristics the presence of several non-functional pixels on the screen. So it’s better to find them in the store and choose a model with a normal screen.
Read more about checking for .

5. Matrix response time(response time). This parameter shows how long it takes for the crystal to change its position in one pixel for different bandwidths. Today this parameter lies within a few milliseconds. This characteristic is very important for the quality indicator of the LCD matrix, so manufacturers pay great attention to reducing this parameter. Companies define this parameter differently, so it may happen that TVs show the same thing with different response times. For example, in order to achieve a minimum response time, they measure it when a pixel transitions from a fully open state (white color on the screen) to a completely closed state (black screen). But then the greatest voltage is applied to the pixel and, accordingly, the rate of change in the position of the crystals is the greatest. And if you measure the transition time between grayscale levels, which is what happens in a real image, then the response time is not so short.

Therefore, take into account the passport data, but still check the picture quality yourself. The response time can be tested on a very fast changing image (for example, a race). With normal response time there should be no trails behind the image.

6. Screen resolution. This parameter shows how many dots are used to create a picture on the screen. Resolution is denoted as the ratio of the number of horizontal pixels to the number of vertical pixels. For example, the designation 1920x1080 indicates that this TV has a screen consisting of 1920 pixels horizontally and 1080 pixels vertically. These dots are called pixels, and each pixel consists of three components: red, green and blue. If you look at the screen from a very close distance, you can see the pixels and three multi-colored dots that make up the screen. The more pixels on the screen, the better the signal the TV can display, but accordingly, the more expensive it is. In addition to the fact that the screen consists of a certain number of dots, the signal entering the TV input also has its own resolution. For example, a television signal from the air has a resolution of 720x576. Therefore, you can only take full advantage of high resolution if you view the signal at the same resolution as the display is designed for. If a television signal of 720x576 pixels is supplied to a screen with a resolution of 1920x1080, the result may be even worse than that of a CRT TV. But if you feed this TV a signal with a resolution of 1920x1080, the result will be magnificent.
More details about.

A signal with a resolution of 1920x1080 is called HDTV or otherwise Full HD. To play it you need blu-ray players and appropriate discs. There are also TVs with a screen resolution of 1366x768 pixels. Today, most models come with 4K Ultra HD resolution (3840 × 2160).

8. Screen diagonal. The screen diagonal is measured in inches and is also recorded in the passport. The diagonal size is in the very name of the TV; it is a number, for example 32, 21, 42, 37 or another. When choosing a screen diagonal, you need to take into account the distance from which you will watch TV. The distance to the TV should be approximately 3-4 screen diagonals. It should be taken into account that the closer you are to the screen, the more noticeable the distortions in the picture will be, but these distortions will be less, the higher the screen resolution. In other words, the higher the resolution of the TV, the closer you can watch it, but you don’t need to watch from such a distance that you have to turn your head, you can get tired quickly.
Read more about.

9. Image contrast. The contrast value shows how many times one area of the image is brighter than another area of the picture. In the TV passport, the contrast can be written in the form: 800:1, showing the ratio of the white level on the screen to the black level. For LCD TVs, a distinction is made between static and dynamic contrast.
Static Contrast indicates the LCD matrix parameter, which shows how many times the brightest picture will be lighter than the darkest picture on the screen. This value is limited due to technological difficulties. A cell with a liquid crystal cannot completely block the passage of light from the backlight, so it is difficult to obtain completely black light on an LCD screen. But the color saturation and clarity of the picture depend on the contrast of the TV. With low contrast, the black areas of the image will appear gray. Dynamic contrast has large values in the passport and reaches tens of thousands.
Dynamic Contrast differs from static in that it changes depending on the characteristics of the displayed image. When displaying a brighter image, the brightness of the matrix backlight increases, and in dark scenes, the backlight brightness decreases. Indeed, in scenes with high brightness, dark areas of the image are not so important, because our eye perceives them as very dark, so increasing the brightness of the backlight will not distort the overall picture. Likewise, in dark scenes, our eyes perceive light areas differently, which makes it possible to reduce the brightness of the backlight. Therefore, to measure dynamic contrast, take the white level at the brightest backlight, and the black level at the most minimal backlight. This is how we get such large values. But at any given time, the screen contrast does not exceed the static contrast value. Dynamic contrast only works when the picture is changing. Therefore, the value of static contrast is of greater importance.

Today, the development of televisions is as rapid as that of computers. More and more new technologies are appearing. In such conditions, information becomes outdated very quickly, and advice on choosing TV that worked yesterday may be useless today. It is important to be able to navigate all this variety of manufacturers, because it often happens that in order to attract buyers they resort to various tricks. There are many models that at first glance do not differ from each other. But don't worry, this article will clear things up. After reading it, you can go to the store yourself and consciously choose exactly the TV model that will meet all your requirements.

The choice may depend on many parameters. Here, it all depends on your needs. You need to decide whether you will watch high-definition movies or regular news broadcasts on it; Do you need support for digital channels? whether you will connect the TV to your computer using HDMI or Ethernet connectors; watch photos and movies from or . The price of the future device, its size and set of functions depend on this. But first things first.

First, let's define the screen types. Naturally, we will not consider CRT TVs, as is done on most sites. They are completely hopelessly outdated, and this technology is absolutely not in demand. Today you only have to choose between two really successful types of screens: Liquid crystal (LCD or LCD) and plasma. Each of them is good in its own way, so it makes sense to understand the issue in more detail.

Types of screens

Liquid crystal display (or LCD, LCD)

The most common technology today. This TV screen includes a matrix and backlight. In this case, the matrix is a fine grid of pixels, each of which, respectively, consists of subpixels (red, green and blue). To form a picture, the property of the crystals in the matrix is used - under the influence of an electric field, they are able to change their position, thereby either opening or closing the light from the backlight located behind the matrix.

Pixel circuit:

A special chip controls the transparency of subpixels. If all three are completely transparent, then the color of the entire pixel will be white; if all three subpixels are opaque, the pixel will be black. To form other colors and their shades, the microcircuit mixes red, green and blue in a certain proportion.

There are several disadvantages to using such an algorithm. One of them is the installation of powerful lamps to illuminate the not completely transparent matrix. The brighter the backlight, the more colorful the picture. Which, in turn, entails an increase in energy consumption and the price of the TV. The second drawback is the inability to achieve a perfectly black color, since the matrix cannot completely block powerful streams of light. And if the first problem can be partially dealt with by, then the second problem is still relevant. Previously, there was also a problem with viewing angles, but modern models have already done a lot of work in this direction, and today the situation is satisfactory.

The advantages of liquid crystal screen technology include, first of all, low cost and a huge selection of models. Everyone will be able to choose a decent TV that they can afford. Such displays have fairly good contrast (from 500:1 to 1,000,000:1) and brightness (250-1500 cd/m2). Thanks to LED backlighting, which was mentioned above, it is possible to reduce the energy consumption of LCD TVs, and the technology itself involves the use of small-thickness matrices. Such screens are lightweight and can be safely mounted directly on the wall.

In general, liquid crystal displays are very successful. Their only alternative today is plasma TVs, which have both a number of advantages and several disadvantages.

Plasma panels

A plasma TV is a matrix of small sealed sections, each of which is filled with xenon or neon. Special transparent electrodes supply the cells with an electric current of such strength that the gas inside the section turns into a plasma state, emitting ultraviolet radiation. It hits the phosphor, which is applied to the cell wall and, depending on the composition, glows red, green or blue. Accordingly, the higher the voltage applied to the electrode and the cell, the more it glows. By mixing three colors we get any shades we need.

These TVs are distinguished by excellent picture quality: rich and bright colors, high contrast. All this is based on technology. A cell in its inactive state, that is, when no voltage is applied to it, is completely black, unlike a pixel in an LCD display. And in the presence of voltage, its light passes through the matrix unhindered, therefore, it is characterized by high intensity. In terms of picture brightness, plasma TVs are approximately 3 times superior to LCD displays.

But it was not without its drawbacks. The main problem is the difficulty of manufacturing small sections with gas. Large cells for plasma panels are easier to manufacture, which is why wide-format (50 inches and larger) plasma TVs appeared much earlier than LCDs of the same size. However, if you need a small plasma TV (up to 32 inches), then difficulties arise; such models are very expensive and rare.

Thus, plasma panels with large diagonals, excellent color rendition and contrast are the best option for film buffs and just people who love high-quality images and are willing to put up with large dimensions and high power consumption.

Now let's move on to the characteristics of the TVs. What you should pay special attention to when choosing.

TV specifications

Screen diagonal

In fact, this is one of the most important parameters for a TV and, in general, any screen. It is the diagonal that primarily affects the size, weight and thickness of the screen, and its price. You need to take your choice very seriously, because in order to enjoy watching, everything must be balanced.

All over the world, screen sizes are indicated in inches. In this case, 1 inch is equal to 2.54 centimeters. The diagonal size is indicated, for example, like this: 32”.

When choosing a TV, do not forget that its size should match the size of your room. The most common formats today are diagonals from 26" to 42". It is logical that you need to put a large TV (from 32”) in the living room, because the whole family and friends can gather there. It is better to connect high-definition digital television and home theater with high-quality acoustics to it.

But in the kitchen or bedroom you can get by with a smaller screen. Previously, there was information about the ratio of the diagonal to the distance from which this TV should be viewed as 1 to 3. That is, a 32” TV should be viewed from a distance of approximately 2.4 meters. But today this ratio is practically irrelevant. A comfortable distance is already taken as 1 to 2 or even 1 to 1.5, that is, the same 32 inches can be viewed from a distance of about one and a half meters. Therefore, for the kitchen we recommend TVs with a diagonal of up to 26 inches, and in the bedroom you can try installing slightly larger sizes – up to 32”.

In order not to make a mistake with your choice and not to buy a device that is too large, we advise you to roughly estimate at home how your future TV will look. In stores, displays are specially displayed in large halls, where the buyer cannot adequately imagine the size of the screen. As a result, it turns out that the TV looks normal when you buy it, but at home it turns out to be simply huge.

Display resolution

Choosing the right resolution today is not so difficult. To begin with, it is worth noting that in general, resolution is the number of pixels on the screen. The larger it is, the smaller each of the cells and, accordingly, the higher the quality of the picture.

The resolution is written in two numbers, for example, 1920x1080. The first of them is the number of pixels horizontally (width), the second is the number of pixels vertically (height).

TVs with the same diagonal may have different resolutions. And the one that has a higher resolution will show a clearer and more detailed picture. For example, with a 42” diagonal, you can find copies with a resolution of 1920x1080 and 1366x768. Obviously the first one will be much better.

The highest quality TVs are those that support high-definition formats, which have several standards:

720p: 1280x720, progressive scan;
1080i: 1920x1080, interlaced;
1080p: 1920x1080, progressive scan.

Interlace scanning (labeled "i") is not very good, so we recommend that you buy devices that support progressive scanning (letter "p"). Progressive scanning algorithms practically eliminate the ladder effect at the boundaries of objects.

Generally speaking, we recommend choosing TVs with FullHD, that is, a resolution of 1920x1080 and support for progressive scan. Many companies provide access to high definition television, that is, HDTV. Only with a FullHD screen you can appreciate all the charm and beauty of the picture. Movies and TV shows also look much better on this display. Don’t settle for less; besides, today such TVs are quite affordable.

Brightness and Contrast

The brightness of the screen determines the comfort of watching TV, as well as the richness and colorfulness of the picture. Brightness is measured in cd\m2 (candelas per square meter) and represents the luminous intensity per unit area. Here, if we compare LCD screens with plasma panels, it is obvious that the latter win. Although LCDs have recently been catching up with them in this regard, the design differences are making themselves felt.
The most common values for this parameter are 300-600 cd/m2 for LED-backlit LCDs and up to 1500 for plasma TVs. Focus on these values when choosing your device.

As for contrast, the point here is as follows. It expresses the ratio of the lightest point on the screen to the darkest. For example, if you see a contrast value of 1000 to 1, then this means that the white area on the TV is 1000 times lighter than the black area. Accordingly, the parameter also affects eye fatigue, picture quality, and so on.

Now it’s worth talking about acceptable values and the ratio of brightness and contrast. For a standard LCD TV with a brightness of 300 cd/m2, the optimal contrast will be from 1000:1. For a brightness of 400-500 cd/m2 it will be from 5000:1 to 10000:1. Well, the most advanced models have a brightness of 600 cd/m2 and higher, with a contrast of 20,000:1.

Don’t be afraid to buy TVs with excessive brightness, because in extreme cases it can be reduced programmatically, but choosing a display that is too dark will be a big mistake.

Response time

This parameter refers specifically to the matrix itself; therefore, it was not used in non-matrix televisions (CRTs). Now it is quite important, and it is also worth paying attention to when choosing a TV. Response time is the average time it takes a matrix element to transition from one state to another. According to the standard, this refers to the transition of a pixel from black to white and back. However, some companies measure the parameter according to the “GtG” scheme, that is, from gray to gray.

The response time should be between 2 and 8 milliseconds. This is done so that when viewing dynamic scenes with fast-moving objects, such as on sports channels, a trail does not appear and the picture does not blur. When connecting a TV to a computer as a main monitor or even an extended one, it is better to choose models with a matrix response time of up to 5ms.

All of the above applies only to LCD displays; when buying a plasma panel, you can ignore this parameter, it is negligible there.

Screen viewing angles

An important characteristic, however, it is not critical when choosing a TV. The thing is that liquid crystal displays are built in such a way that their cells are isolated from each other by special polarizing filters. In their normal position, that is, perpendicular to the screen, the filters are not noticeable, but if you deviate to the side at a certain angle, they can significantly degrade the brightness and contrast of the picture.

So, for most models, the most comfortable angles are 60 degrees on each side, that is, 120 in total. After them, the picture begins to deteriorate little by little, but up to about 160 degrees it is still barely noticeable.

And only flagship models, that is, the most advanced and expensive, can reach the result of 175-178 degrees. The polarizing filters there are very tiny and have virtually no effect on the picture. It is worth noting that for plasma TVs, viewing angles are always close to 180 degrees, since the matrix there is arranged differently, as already mentioned in the first paragraph of the article.

Sound system

If we are talking about a widescreen TV for the living room, where the quality of both picture and sound is important, then it is recommended to connect a separate speaker system with several satellite speakers, as well as a subwoofer. But, if you choose an option for a bedroom or kitchen, then to save space you can get by with built-in acoustics, which, by the way, in modern models are at a fairly high level.
The power of the speakers of the built-in audio system is selected in such a way as to meet the needs of users. Thus, if the screen diagonal is not large and you will be watching TV from a short distance, then you can make do with 5-watt speakers. If the diagonal is large, that is, from 32” inches, then the speakers have a power of 10-15 W and higher to cover the size of the room where the device is installed.

Also, when choosing a TV for the living room, we recommend paying attention to the presence of a Dolby Digital processing processor if you are going to connect it to an external speaker system. Such a processor will independently decode the sound signal and send it to the acoustics, otherwise you will have to connect, in addition to the acoustics itself, a digital decoder, which means extra space, tangled wires and financial expenses.

Interfaces and connectors

HDMI is one of the most modern data transfer interfaces between a TV and a computer. It is also used when connecting to a multimedia system or home theater. The cable is multi-channel, usually up to 5 meters long. It transmits video in resolutions up to 2560×1440, as well as sound.

USB is a connector that was originally intended for computers, but can now be found on televisions as well. To put it simply, you need it to connect flash drives and external hard drives to it. From such storage media you can watch movies and videos, listen to music, view photos, and all this without any additional conversions or manipulations.

Ethernet – connector for connecting devices via twisted pair. Specifically, there will be a TV, and then a router for external storage devices and a computer. Thus, the device gets into your home local network, which gives you a lot of possibilities. The most important thing here is access to DLNA for sharing media content between your TV and computer or any other devices on the network.

Wifi provides the same capabilities as an Ethernet port, but without wires. All information is transmitted by radio waves.

These parameters are quite enough to understand how to choose a TV. Now all that remains is to use the acquired knowledge and recommendations and still go to the store and choose the right model.

In the physical world, everything is related to measurements and everything can be described and measured. And for every object or phenomenon there are units of measurement. For example, distance is measured in meters, temperature in degrees, and mass in kilograms. Light also has measurable parameters: luminosity, brightness, luminous intensity, which also have their own units. For example, the unit of brightness is candela per meter squared.

Light emission parameters

Light as a physical phenomenon is characterized by many parameters. The main ones used in physics are:

The power of light;
Luminosity;
Brightness;
Illumination;
Light temperature.

Luminous intensity determines the amount of light energy emitted by a light source over a period of time. In other words, this is how powerful the luminous flux a light source is capable of emitting.

Luminosity is the luminous flux per unit of luminous surface. The greater the luminosity, the lighter the emitting surface appears. The unit of luminosity is lumen per square meter.

Brightness is the luminous flux in a certain, narrow direction. This quantity is usually spoken of in the context of a point source of radiation. If the luminous area is large, its average brightness is determined.

The term illuminance is applied to the illuminated surface. This is the ratio of luminous flux to surface area, that is, how well it is illuminated.

Light temperature indicates the perceived color of a radiation source. It is measured in temperature units - Kelvin - and corresponds to the temperature of the radiating body heated to these degrees. Subjectively, it is perceived as warm or cold. The higher the color temperature, the cooler the color will be. Warm is yellow and reddish, cold is blue and violet.

Brightness measurement

Since light has measurable parameters, brightness as a parameter of light has its own units of measurement. Now, according to the international SI system, brightness is measured in candelas per square meter, the value of this unit corresponds to the ancient unit of nits, the value of which was expressed as the ratio of one candela to one meter squared. In addition to nits, brightness units were also:

Stilb;
Apostilbe;
Lambert.

Apostilbe is currently an obsolete quantity, having fallen out of use in 1978. It indicated the brightness of a surface with an area of 1 square meter and emitting a luminous flux of 1 lumen.

The stilb size is used in the GHS measurement system. In this system, the main measures are measures of length, weight and time, which in the decoding of the abbreviation GHS corresponds to the values centimeter, gram, second. In later versions of the system, electrical and magnetic extensions of SGSE and SGSM appeared. This is where the stilbe is located, as a unit of measurement of electromagnetic radiation.

Lambert is a non-system unit. Appeared and is used mainly in America. Its name comes from the name of the German physicist Johann Lambert, who conducted research in systems theory, irrational numbers, photometry and trigonometry. One lambert is a unit of brightness a luminous surface with an area of one square centimeter and a luminous flux of one lumen.

Physical representation

And in physics, the quantity under consideration can be expressed through the concept of work. Work is understood as the exchange of energies between the system and the external environment. The exchange can occur in the form of electromagnetic radiation. The intensity of the radiation will determine the brightness. If you understand how work is measured in physics, you can determine the physical representation of brightness. Work in physics is measured in joules, which can be thought of as watt-seconds. That is, the radiation power multiplied by time will be considered work. The greater the power of light radiation, the brighter the light source will be.

Application in astronomy

Astronomy also uses units to measure brightness for celestial bodies. They characterize celestial bodies by emissivity or reflectivity. The reflected light of celestial bodies can be very bright; just remember the light of the Moon or the morning Venus eclipsing the light of many stars. Both of these celestial bodies shine with reflected light from the Sun.

The unit of brightness of celestial bodies is expressed as the magnitude of a section of the sky measuring one square second. In simple words, magnitude can be defined as the luminosity of a point object in the starry sky. A square second is 1/648,000 of a volumetric angle called a steradian.

Astronomical brightness can be compared with normal brightness. One magnitude per square second is equal to 8.96 microcandelas per square meter.

The brightness of the sky on a moonless night is expressed as 0.0002 cd/m2. Measuring the lightness of dark objects is important for photometry: in this way you can understand which object in the starry sky and how much it overlaps other objects with luminosity. By reducing the intensity of the light of stars, they judge the possible occlusion of their luminous disk by planets, and even the size and composition of the atmosphere of these planets! This quantity plays an important role in astronomy, photography and videography, as well as from artists and workplace lighting specialists.

For TV screens

Modern plasma and LCD TV screens can reach a brightness of 400−500 cd/m2. However, this is a dubious advantage, since an increase in this value leads to increased eye fatigue and requires an increase in the frequency and duration of rest. This especially affects the eye when watching TV or working on a computer in the dark or in low light. For the human eye, a comfortable value is set within 150−200 candelas per square meter. Sanitary rules and regulations set a limit on screen brightness during operation of 200 cd/m2.

An increased radiation intensity value is only welcome when watching films with a 3D effect, since the 3D glasses used in this case strongly absorb the radiation of the screen, making it darker. When choosing devices with LCD and plasma screens, you should pay attention to the uniformity of the backlight. Poor quality screens display the center brighter, and the decrease in backlight power towards the edges of the display turns out to be very noticeable.