4Ks for checking TV
Digital technologies are developing at a rapid pace, and today viewers can enjoy such a clear and perfect picture that a few decades ago it seemed fantastic.
Modern TV-receivers reproduce a wide variety of formats, including 4K. For comparison, a Full HD picture has a horizontal resolution of 1920 pixels, while 4K is characterized by about 4000 pixels. Buying a new TV is a crucial step, and if a consumer is ready to pay a round sum for a plasma panel, he must make sure that the purchased product is worth that kind of money.
Checking 4K TVs
- Defective pixels. This defect manifests itself only under certain conditions. If a pixel is completely inoperative, it is easy to see with the naked eye, but a partial defect is not so easy to notice. Each point is formed from three components of different colors (red, green and blue). If one of the pixels starts to work incorrectly, then one of the points is displayed in a wrong color. If the screen diagonal is about 50 inches, the “saboteur” can be calculated using test pictures or 4K clIPs. In this case, the TV check is performed as follows: the screen displays content with patterns, strIPes or evenly alternating shapes. If there are elements that are not functioning correctly, they will stand out in the general row.
- Backlight uniformity testing. A black fill will help here. If light spots appear on different parts of the screen or white characters on a black background, then the TV is defective. Most manufacturers do NOT consider uneven backlighting to be a serious defect and therefore is NOT a reason for returning the TV.
- The presence of colored spots. Particular attention should be paid to the white fill as well. The defect appears as green or pink areas on a white background. Experts also recommend checking the TV for banding. This flaw is easily recognized by the developing strIPes of other colors. It is easier to find when watchings that show homogeneous areas as the camera moves.
But not all TVs, which have high resolution, allow viewing in 4K format. When buying a receiver, pay attention to whether it has an Ultra HD sticker on it. It is also worth finding out what standard it meets. TV must play content with a resolution of at least 3840 x 2160 pixels, and the minimum frame rate is 60 units per second.
4K TV rating
To choose a good TV, it is recommended to study the rating of 4K devices. The most popular manufacturers are LG and Samsung. They compete with each other in different areas, including display technology. If a user wants to buy an inexpensive 4K TV, he should pay attention to the Samsung UE43RU7400U or LG 43UK6750 model. The cost varies from 28,000 to 32,000 rubles. PhilIPs 43PUS6503 can also be included in this category, the price of which is kept at about 25,000 rubles.
From the middle class category it is worth highlighting Samsung UE49RU8000U (about 43,000 rubles) and LG49SK8100 (about 45,000 rubles).
Sony is a serious brand. Having financial capabilities, you can pay attention to the KD-49 XF8596 model, its cost is about 62,000 rubles.
Sony KD-49 XF8596
Premium-class products boast wider functionality, including the presence of Smart technology. The ranking includes Samsung QE55Q90RAU and Sony KD-55XF9005. If we compare them in price, then the first model is estimated at about 154,000 rubles, and the second costs about 65,000 rubles.
Among the best 4K OLED panels, LG OLED65C8, Sony KD55AF9 and Panasonic TX-65FZR800 occupy special positions in the ranking. Their cost varies from 130,000 to 194,000 rubles.
Test images for each setting
Such pictures are used for only one setting, in contrast to pictures with MultIPle test zones. Therefore, after performing one setting, you need to change the picture to another and adjust the second parameter. The setting procedure is described below.
MultIPle test zones
Pictures with a large number of test zones (five zones are used here) are intended for setting up the TV by inexperienced users or for quick setup. On each such picture, you can configure five main parameters at once I control them on the screen.
The initial setup of the TV must be carried out either with the help of five primary test pictures or with one of the presented here.
Adjust the screen format or size. For correct adjustment, you need to disable various image scaling functions in the menu. Different manufacturers call these scaling functions (resizing images) in their own way.
After all the settings, you can include real photos in the desired resolution from the set. Using these pictures, you check the naturalness of all settings.
Setting up and adjusting the TV
Various Full HD and Ultra HD tests from Burosch are used as reference and are used to assess the picture quality on a TV or monitor.
With the help of such tests, you can optimize and adjust the image. You just need to achieve the correct display of pictures from the test on the screen and we can say that your TV is set.
Such customization occurs regardless of the screen size and is assessed by eye, each user customizes for himself.
All pictures are static to give time for the eyes to identify inaccuracies in the display on the screen.
Test images are divided into five groups:
- Basic samples for initial visual adjustments
- Test images for metrological calibration with light sensor
- Professional static reference images for image optimization
- Dynamic test rollers
- Professionally made real pictures
These are the common characteristics of tests that may be encountered. In our tests, there are only a few pictures, but they are quite enough for setting up the TV.
Each test image serves for setting a separate parameter.
Our test has:
- Five basic images for the first basic setting of the picture quality on the screen:
Other test pictures
For example, solid color images are needed to test the health of the pixels on the screen. Various grid images can also be used to detect broken pixels that stop working at a certain position of neighboring pixels.
Colored strIPes are used to check chromaticity. Different shades of gray are used to check the white balance (there are color tints) and to check the brightness and contrast.
Download test pictures in Ultra HD 4K resolution (3840×2160) here.
Test images with Full HD resolution (1920×1080) here.
How many dead pixels are acceptable? The answer to this question is contained in the international quality standard for LCD TVs ISO 13406-2. It identifies 3 types of defective points:
- Open or white. such pixels freeze in the open state and constantly glow white.
- Closed or black. such pixels freeze when closed and constantly glow black.
- Colored. in such pixels the control transistor fails, and they are constantly lit in one of 3 colors: red, green or blue.
Also LCD devices are divided into 4 classes. The first class is the highest, the presence of defective points is generally not allowed in the matrix of devices of this class. The bulk of devices on the market are second class. The standard defines the allowable number of different types of defective dots depending on the maximum resolution it supports. Information for popular 2nd class devices is shown in the table below.
|Pixel Type \ Max Resolution||1280 × 720 (720p, HD Ready)||1920 × 1080 (1080p, Full HD)|
Why are some dead pixels allowed? The fact is that the technology for the production of LCD matrixes is very complex, and not even every device manufacturer can afford their own production. And such a defect can only be detected on the assembled device. If the manufacturer scraps screens even with minor defects, then the price of TVs and monitors will increase several times. Therefore, such a compromise was found:
- Manufacturers keep production at the same level and do NOT raise prices.
- Buyers admit the presence of a certain number of dead pixels, which is NOT a warranty case. In this case, the buyer has the right to check the display before purchasing.
How to check
To check the screen for defects, you need to successively submit pictures of the primary colors to it, and at the same time carefully look at it, trying to find points of the second color. This is what broken pixels look like. For example, when there is a white picture on the screen, it is easy to detect black and colored dots. If black is served, then it is easy to detect white dots, etc. Before testing with the TV off, make sure there are no dust particles or other debris on the screen.
Test the screen for dead pixels yourself
When buying a TV or monitor, sellers offer to use an additional service. check for dead pixels. over, the service is paid, costing from 500 rubles and more. If you find a defect at home, you will NOT be able to return the TV back, they explain. After all, this is not a guarantee case, and they are right. In fact, you can perform such a matrix test yourself and for free, there is nothing complicated about it. It is enough just to bring a special one or pictures for verification with you on a USB flash drive, read our article before.
There are several ways to recover dead pixels found during the test. They give the result extremely rarely and only in the correction of colored dots (3rd type). Tests also show that it usually helps for a short time, the next day the pixel fails again. Plus, you can easily mess up neighboring points. Therefore, we highly do not recommend doing recovery, but we will still consider the methods:
- Programmatic approach. A matrix picture is displayed on the screen, in which dots of different colors are randomly displayed. The problem pixel should be restored within 20 minutes;
- Mechanical approach. I turn off the TV, press on the broken pixel with a napkin, turn on the device and stop pressing. This method can harm the matrix.
What to check first on TV
External inspection upon purchase
First, we check the packaging for various damages (dents, tears), if during transportation there were any blows to the packaging, then the TV got it. Then we check the presence of all correctly completed documents, such as a passport for the device, a warranty card. The coupon must be filled out correctly by the seller (warranty period, date of sale, stamp), the serial number on the coupon must match the number on the TV.
We check the external condition of the TV and the remote control. Look for scuffs, chIPs, cracks, etc. The screws on the back of the TV must NOT show signs of tampering, otherwise your TV was already on sale and under repair.
By model name, serial number and product code, you can find out where and when this TV was made and for which country.
After that, you can turn on the TV and check its operation. Correctness of the remote control, work with external sources (USB flash drives, players, etc.). You can take your USB flash drive, pre-recorded high-resolutions on it, and pictures to check for dead pixels.
Check for dead pixels
When forming a picture on a TV screen, all display pixels must be involved. At a Full HD screen resolution, the entire display field consists of 1920 x 1080 pixels, which is just over 2 million points.
According to the rules, a certain number of non-working pixels is allowed, different norms allow a different number of defective pixels. So, having identified this defect at home in the form of one or two broken pixels, you will NOT be able to return the TV back, so it is better to do this check before buying.
To search for defective pixels on the screen, you need to submit an image with a certain picture and examine the screen from a close distance. You can also use a magnifying glass. You need to look for a pixel that does not glow in the same color as all the others. The image must match the screen resolution exactly.
Completely inoperative pixels that DO NOT respond to the signal and are in a constant position can be found in a uniform picture (filled with one color). White, black and primary colors (red, blue, green) pictures are alternately fed to the screen and pixels of the second color are looked for on them.
Broken pixel on black background Broken sub-pixel on screen
There are such defective pixels, which begin to work poorly when the matrix heats up. You can identify them after the TV has been running for a while.
There are pixels that do not work correctly depending on the work of the neighboring sub-pixels. You can detect such defects if a picture is presented to the screen in the form of a checkerboard fill, color strIPes, gradations, a grid. Incorrectly working pixels will stand out from the general structure of the picture.
The necessary pictures for checking the picture on the TV can be downloaded here. Resolution of verification images 1920 x 1080 pixels.
To test Ultra HD 4K TVs test pictures here.
How to use these images can be read here.
Non-uniform screen illumination
When a signal with a uniform color fill (colored with one color) is input to the TV input, the screen should have this color without any color shades. But, due to the technological peculiarities of manufacturing displays with LED backlight, such a uniform illumination is difficult to achieve. Therefore, it is advisable to check the uniformity of the color field before purchasing. Usually, such a defect is not considered a breakdown and the TV cannot be returned or repaired.
Such screen defects are called banding, flashing and Tinto.
Tinto can be translated as “color tone” and it shows how correctly white is displayed on the screen. When viewing normal, you may NOT see this defect, because the picture is constantly changing there. But if the picture is static, then the interference can be very noticeable and interfere with normal viewing.
To identify Tinto, you need to apply a white or gray field to the screen. Interference in the form of strIPes, spots and other shapes, painted in a different tone, against a uniform background, may indicate the presence of a Tinto defect. Such noise is usually pink or greenish and is located near the edges of the screen.
If the defect is very noticeable, then it is better to choose another TV.
Tinto large and clearly visible Tinto interference tolerance
Level of banding is unacceptable
Glare can only be found in LED TVs. To evaluate the quality of the display by the level of light, you need to do this in a completely dark room (Turn off the light and shade the windows). In this case, on the TV, you need to select the maximum backlight level, for this you can select the Corresponding mode (it can be called “bright”, “dynamic” or in another way). You need to disable image enhancement modes such as Dynamic Backlight, Black Level Correction, Eco Sensor, and others. This is done so that the TV does NOT adjust the backlight when checking.
But even so, errors may arise due to the automation of the TV receiver, when a completely black frame is fed. Indeed, with a black picture, the TV turns off the backlight. Therefore, to detect highlights, it is better to submit a black picture with some bright elements, for example, white titles on a black background at the end of the film.
Then, from a distance, look for screen glare, especially in the corners. Some minimal highlights are quite acceptable for normal GoPro viewing.
The level of glare is unacceptable
Finding an LED TV completely free of THESE defects (Tinto, banding, light) is unlikely to work, but you need to choose a model with a minimum level of THESE interference.