In TVs and monitors, there are two main parameters that have a very strong effect on image quality: brightness and contrast. Such parameters are present in all monitors and TV sets, but few people have thought about what these parameters mean and how the screen physically reacts to changes in brightness and contrast parameters. These are two interrelated parameters and the image settings shall be made taking into account the specifics of both parameters.

Contrast in LED, QLED, OLED TV and monitor

Contrast is the ratio of the brightest part of the screen to the darkest part of the screen. If 2500:1 is specified, it means that the brightest part of the screen can be 2500 times brighter than the darkest part of the screen. In other words, if you look at a black screen, the white screen will be 2500 times brighter than the darkest part of the screen.

But to tell you the truth, there is no single measurement technique, and the manufacturer can measure this parameter at will, sometimes even grossly violating the logic of measurement. Ideally it is necessary to establish in the TV brightness on some parameter, for example 50 % and to carry out measurements of brightness of the black screen with contrast 0 and the white screen with contrast 100, you never will receive a parameter 2500:1 and if to establish brightness and contrast on 0 and to carry out brightness measurement, and then to establish brightness and contrast on 100 % it is possible and to receive just 2500. But as you understand, nobody will constantly change brightness and contrast when watching a movie.

How the contrast works in the TV and monitor LED and OLED

How Contrast works in LED and QLED screens – LED screens have backlit light passing through pixels of a certain color and create an image. Pixels are crystals that change the amount of light transmitted, pixels are made as crystals of rotating cells and can transmit from 0% to 100% of light flow. Contrast sets how much light flux a pixel should transmit (by how much it should rotate in a cell). At contrast 0 pixels transmit about 10-20% of light flux, at contrast level 100,
pixels of the screen transmit all the light stream. Contrast in LED screen sets how much light flux a pixel should pass.

image 50% brightness, 0 contrast

As we can see the contrast change on the LED screen, the image will fade as the contrast decreases.

How Contrast works in an OLED screen – since OLED is a screen in which a pixel emits light, contrast works differently from LED. In OLED, contrast sets how much the brightness of the black pixel should differ (turned off from turned on to the maximum brightness).
But brightness plays a big role in OLED, brightness adjustment sets the minimum level of pixel glow. Therefore, contrast in OLED is a part of brightness adjustment. When contrast is changed in OLED, the brightness level changes.

How to set the contrast level when adjusting the TV or monitor.

Practice shows that the higher the contrast level, the better at any type of screen. Therefore, as a rule, the contrast level is set to 80-100. Contrast came from kinetoscopic TVs, then it really was the right setting. In modern digital TVs, the contrast can be removed from the settings in general, but everyone is used to the settings is the contrast, so this option is used in TVs and monitors, but for example, in laptops and phones do not adjust the screen contrast, there is only brightness.

Brightness in LED TVs and monitors

Brightness in LED screens is a change in the brightness of the backlighting LEDs. In LED screens, the brightness is greatly influenced by the very technology of manufacturing panels. At very high brightness, light begins to penetrate through the edges of pixels in the cells and the image loses contrast and color.

Brightness in OLED screens is the brightness level of all pixels on the screen. Brightness is then affected by the image, if the video part of the image is bright, pixels will glow more strongly, if the image part is black, then pixels will be turned off at all in this part of the screen.

Why do you need brightness in TVs and monitors?

Brightness is only needed to increase the visibility of the screen in different external light conditions. For example, in a dark room the brightness should be set lower, because at high brightness will hurt your eyes. Brightness should be set higher in the light room, and you will not see the image in dark tones if image brightness is insufficient.

What are the brightness parameters?

There are three types of brightness indicated by TV and monitor manufacturers

  • Standard brightness is the brightness at normal TV settings, usually it is 350cd/m2.
  • The minimum brightness is the brightness when adjusting the brightness level 0 and the brightness level is 300cd/m2.
  • Peak brightness – the brightness at the maximum brightness level of 100 and on white background is about 600cd/m2.

The parameters may change depending on the screen type. But when choosing a TV and monitor, there is no point in paying attention to the minimum and peak brightness parameter, you will never watch video with such brightness. It is best to pay attention to the standard brightness, but for example, on TVs, manufacturers may not specify this parameter.

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