Low image brightness. Technical characteristics What is cd m2 for a monitor

An LCD monitor is a liquid crystal monitor that uses an active matrix.

Liquid crystal The monitor is designed to display graphic information from a computer, TV receiver, digital camera, electronic translator, etc.

The image is formed using individual elements, usually through a scanning system. Simple devices can have a monochrome or 2-5 color display.

Many owners of LCD monitors have encountered a common problem, namely, uneven picture brightness. To more accurately understand what is happening, it is necessary to take a little look at the structure of LCD monitors.

An LCD monitor consists of two main elements:

• matrix that transmits the image;
• an LED or LED backlight system, which is located behind the matrix and performs the basic function of illuminating the picture on the matrix.

The problem with uneven backlighting is related specifically to the second element of the monitor. It often happens that a defective product arrives from the factory, which for the following reasons shows an uneven image:

• rows of LEDs are not placed correctly;
• there was a failure on the conveyor and a certain number of LEDs were not secured at all, or were placed very close to each other;
• engineering design error. Rows of LEDs are placed close to the sides of the monitor, which is why the light is reflected and, when added to the light from other diodes, creates overexposure in certain places.

To protect yourself from such troubles, you simply need to carefully select a monitor when purchasing. If you do come across such a monitor, then feel free to replace it under warranty.

During operation, the uniformity of the screen backlight may also change. There are several reasons for this:

• failure of one or more LEDs thereby on the screen;
• Due to use, the LEDs began to emit less light, and the monitor darkened or became stained;
• During the engineering design, the wear of the LEDs was not taken into account, as a result of which they were placed too far from each other. After some wear and tear and a decrease in brightness, dark streaks appeared on the screen.

All problems of this kind can be eliminated by replacing all or several LEDs. To repair such a defect, it is best to contact specialists. Professional technicians who have been repairing such faults for a long time will ensure that your monitor is properly repaired.

image source http://4k-monitor.ru

Good and correct display settings are not the last task in order to work comfortably and efficiently not only with images, but also simply at the computer. The factory settings of monitors are always too high for brightness and contrast; manufacturers do not make adjustments at all, and users themselves often simply do not know about it.

I note that we will talk about the simplest screen settings; professional calibration is much more complicated.

You can configure it both software (if your display is connected to a PC with an operating system that has tools for such settings) and hardware. Adjusting using the menu buttons is not much different from adjusting the picture on a modern TV.

Hardware setup

Start by learning the buttons on your monitor. If nothing is clear, then you will have to read the instructions, or use the “unscientific poking method” (not recommended). After you have figured out the control buttons of the device, you can go directly to the settings.

Important note: ensure proper lighting! If the sun or a 200 W light bulb hits the monitor directly, no adjustments will help. Well, this is a separate big topic, but now there are a few basic recommendations:

• The bright light source should not directly illuminate the monitor;
• The light should not hit the eyes;
• It is better to use uniform diffused lighting, for example, in the form of an LED strip.

Setting and assessing image quality

When working with a monitor with a low-quality matrix, errors often occur when choosing colors when processing images, photographs and on print layouts, when creating websites and resources.

The picture below will allow you to evaluate how well the monitor is configured. On each half of the picture there are numbers 1 2 3 4 5

If you see all the numbers on both bars, then the monitor is set up well. The average level will show you the numbers 3. With a very bad setting, only 1 and 2 are visible.

Remember how many numbers you can see. With this, after configuration, you can evaluate the quality of the improvements made.

But, first, a small off-topic “with a beard”:
“...I downloaded the program “Cleaning the monitor from dust”, laughed, installed it, launched it. The monitor was filled with an even dirty gray color, the keyboard turned off, clicking the mouse did not help.
I took a napkin, wiped the dust off the monitor, and saw a barely visible “Thank you, you can exit the program” button. I went out and thought, looking at the blank monitor...”

Therefore, first we put the surface itself in order, after which we move directly to the settings.

Brightness

The brightness should be adjusted so that in the picture the black colors of the suit and shirt do not merge into a single whole and the cross in the background becomes visible. The brightness parameter is responsible for the difference between details and dark colors.

Contrast

Responsible for light colors and their details.

In the image, to adjust the contrast, you should select a quality such that the folds and buttons on a white shirt are clearly visible. Set the contrast to zero and gradually increase it. As soon as these details begin to disappear, it is worth going back a little.

Gamma

The next important parameter is gamma. The exact ideal setting cannot be performed on all monitors, but it is still worth getting closer to the ideal. A good gamma setting will be indicated by missing spots of light and dark shades in the center of the test image.

Gray setting

Eliminates unnecessary shades that distort the colors on the display. This is done either software or hardware by adjusting the 3 primary colors (red, green, blue). Ideally, a picture with gray stripes should not be interrupted by extraneous shades. Only shades of gray.

Ideal gray setting.

Software setup

We launch the calibration tools programmatically (described for Windows).

In Windows 7, click the “Start” button and write the word “calibration” in the search bar. Launch. You will be given a series of image adjustment tests. There are very few of them. Go through them.

In Windows 10, enter the command cttune in the search bar, ClearType will launch, turn it on and select the display that is most convenient for your eyes. Then enter the dccw command. The calibration of screen colors, gamma, brightness and contrast will begin. Everything is described in the tests, read and follow the advice.

Checking the result

Now go back to the beginning of the article and look at the first image with numbers. At the very beginning, I asked them to remember. If you have improved the settings, you will see at least one more number.

Set it up correctly and in the end you will be pleasantly surprised at what your monitor can do!

Have you set up your monitor? Get to work: profession "".

In order for the monitor to have less of a negative impact on the eyes, it is necessary to minimize the impact of its rays and the load on the visual apparatus. If you are deciding which monitor is better for your eyes, pay attention to the following characteristics:

• In working condition, the screens should be free of any glare;
• It should have a matte body, as well as a keyboard;
• The screen contrast should be high (at least 600:1 - 700:1).

Most computer stores use marketing gimmicks. And in the specifications they indicate a contrast ratio of 1,000,000:1. This is not cheating at all. But there is one caveat. This data is an indicator of a completely black or completely white picture on the screen. When adding any other color (which is necessary), such a characteristic is simply impossible.

LED screens are good eye monitors. They cause minimal harm to the visual apparatus due to the presence of LEDs. Such screens have the following positive characteristics:

• The contrast required for the eyes;
• High picture clarity;
• High brightness;
• Low energy consumption;
• Affordable price;
• Environmental friendliness.

If you are thinking about which monitor is best to choose for eye health, then pay attention to LCD screens. LCDs are the most expensive on the market. This is due to the fact that cyanophenyl is used in their production. Although this substance is in a liquid state, it still retains all the properties of crystals. The price of such screens directly depends on the size. Small in size, accessible to almost everyone. In addition to the fact that such a monitor practically does not tire the eyes, it also does not emit electromagnetic waves. And this has a positive effect on the general condition of the body.

Types of matrix

If you care about your vision, then purchase a monitor with a VA matrix (MVA, PVA and others) or S-IPS. They cause the least harm to your eyes.

Matrices VA, MVA, PVA have less negative impact on the visual apparatus. They allow the screen to project images with high definition. But the price for them, thanks to their excellent characteristics, is not small.

The S-IPS matrix is ​​quite rare. But a monitor with it has fairly high performance and causes minimal harm to eye health. Its cost is quite high. But you must admit, no money can replace health.

Other required characteristics

When purchasing a monitor, also pay attention to the following parameters:

1. Good color rendering performance.
2. Minimum response time.
3. Large viewing angle.

What is needed to minimize negative impact

So, after you have purchased a computer monitor, following all the recommendations listed above, its negative impact can be further reduced. To do this, you need to install the screen at a certain distance.

Final choice

So, having studied all the characteristics of screens, the best for our eyes are screens with the following characteristics:

• Economical option. Equipped with a TFT-TN matrix. Has a brightness of 200 cd/m2. Has a contrast ratio of 600:1. The screen size is 17-19 inches.
• Standard option. TFT-MVA matrix. Brightness 250 cd/m2. Contrast ratio 800:1. Monitor size 19-23 inches.
• High class. Matrix TFT-IPS. Brightness 300 cd/m2. Contrast ratio 1000:1. Size 23 inches or larger.

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. 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. 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. 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. 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. 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. 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).






7. 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.


8. 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.

In this article we will look at the main characteristics of LCD monitors, omitting such an important characteristic as the type of matrix. We will try to understand the types of matrices of LCD monitors in a separate article.

LCD monitors are classified according to their operating resolution. Unlike CRT-based monitors, whose resolution can be changed very flexibly, LCD displays have a fixed set of physical pixels. Therefore, they are designed to work with one fixed resolution, which is called working. For example, monitors with a diagonal of 17 to 19 inches often have a working resolution of 1280 x 1024, which means that a given monitor actually contains 1280 pixels horizontally and 1024 vertically. Accordingly, the higher the resolution, the better the picture quality.

The LCD monitor is capable of displaying images in a different resolution. This mode is called interpolation, but it has its drawbacks. In this mode, in most cases, image deformation may occur: the edges of elements on the screen may become jagged, etc. Therefore, when purchasing an LCD monitor, you should understand that you can only work comfortably in the working resolution.

Brightness

The high brightness of an LCD monitor is its advantage, as it is sometimes twice as high as the same parameter in CRT-based monitors. Today, the brightness of LCD monitors ranges from 300 to 600 cd. The brightness of the monitor is a very important parameter, since if the brightness of the monitor is insufficient, you will not be able to comfortably play games or watch movies. But you should still understand that a significant increase in the brightness of the monitor will also increase the strain on your eyes, so you need to maintain a balance of brightness.

Recently, the contrast of monitor images has increased significantly. Nowadays this figure often reaches 1000:1, and sometimes more. This parameter is defined as the ratio between the maximum and minimum brightness on a white and black background, respectively. As practice shows, if the documentation for the monitor indicates a parameter of more than 500: 1, then this is quite enough for comfortable work.

Viewing angle

The maximum viewing angle is defined as the angle from which the image contrast is at least 10:1. True, for most users contrast is not particularly important; the correct color rendering is a higher priority when changing the viewing angle. For example, red turns into yellow, and green turns into blue. Such distortions manifest themselves differently in different monitor models, so it makes virtually no sense to compare monitors by viewing angle.

Pixel response time

Now we will talk about the pixel reaction time (response time). Very often this characteristic is called the weak point of an LCD monitor. In CRT monitors, the response time is measured in microseconds, and in LCD monitors - in tens of milliseconds, which, when changing the picture in some cases, can be noticeable to the naked eye (although in practice such cases are excluded). When choosing a monitor, pay attention to this characteristic; it is advisable to give preference to models where the pixel response time is shorter.

Monitor interface

For LCD monitors, which are digital devices, the DVI interface is considered native; connection via the D-sub connector is also allowed. The advantage of the DVI interface is that there is no signal conversion in an analog video card (DAC), but it is sent directly in digital form, which reduces the risk of distortion. True, in practice, such distortions do not occur, so you can connect the monitor via any interface, as long as the corresponding connector is present on the video card.

DVI

Let's move on to the new connection standard that replaced DVI - DisplayPort. In the near future, it should become a single interface for connecting various types of monitors. This interface has taken root on Apple laptops and computers. But in the PC world, despite its promotion by AMD/ATI (video cards from this manufacturer have had a corresponding connector since 2007), it is somewhat stalled. NViDIA still prefers HDMI. The new version of the DisplayPort 1.2 connector will provide bandwidth for working with a resolution of 3840x2160. Main Link technology will provide speeds of up to 5 Gbps per lane (there can be up to four lanes in total).

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When purchasing a monitor, you may find dead pixels. These may be glowing black dots that remain unchanged regardless of the dynamics of the image, and these dots may also appear over time. The above means that one or more pixels have failed. This cannot be repaired, but in some cases it can be replaced under warranty, although here you need to read the documentation. Some developers guarantee 100% absence of dead pixels, while others allow the presence of a small amount.