TV response time

One of the important characteristics that determine the image quality of a TV is the response time. It means the necessary time to change the brightness of the pixel.

A pixel is the smallest element of a two-dimensional digital image, or an element of a display matrix that forms an image. Response is measured in milliseconds (ms). The less time it takes to change color, the higher the image quality.

Measurement options

Each manufacturer uses its own standards and rules for measuring response time. Therefore, do not trust the numbers indicated in the characteristic of the TV. Basically, the response speed of a pixel is measured when changing colors according to the following methods:

1. From one shade of gray to another (GtG);
2. From black to white and vice versa (BtB or BWD).

REFERENCE! In this case, the measurement of the response speed is carried out not to a complete color change (100%), but to the level of 90%. It is impossible to determine unequivocally which of the methods is more accurate.

Upon initial consideration, the BWB technique, which covers the largest pixel variation range, should more accurately characterize the response speed. In reality, shots with a sharp transition from white to black are very rare. Most cases are intermediate color transitions. Based on this, none of the methods gives an exact answer to the correctness of the response measurement.

Information characteristics about the time of change from the manufacturer should be considered for a preliminary assessment.

The main measurement option

The method of measuring the response from black to white and back has another name - Time rising, Time falling (TrTf). The largest television companies prefer the TrTf method. This measurement method was adopted as the standard of the first LCD TVs and approved by the Video Electronics Standardization Association (VESA).

In accordance with the standard, the optimal time is 20-25 ms. This indicator of time is comfortable for the perception of rapid changes in video scenes. For some scenes, this time is not enough to eliminate the loop effect on the screen. With an indicator of 8-12, this problem is almost completely exhausted.

REFERENCE! Televisions with high change rates can have a negative effect in the form of flicker. If the lack of televisions with slow response is noticeable in active scenes, then the flicker effect occurs constantly.

If we compare the screen frequency of 50 Hz with the response, then the pixel change time will be equal to 14-16 ms.

The most common and accurate method is considered TrTf. Despite the adopted VESA standard, it is not mandatory for all TV manufacturers. Therefore, do not trust the information specified in the technical specifications. In some models, the response time is simply not indicated. A full speed estimate is performed by comparing one action scene on different TV models.

Reference: Lateral vision is more susceptible to image changes, as well as to flicker. Therefore, the comparison of models must be performed by viewing with side vision, and not with a direct look.

At the moment, VESA is working towards a unified measurement system.

Although response time is an important feature, you should not choose a TV model based on one indicator. It is necessary to take into account such parameters as: diagonal, expansion, brightness, contrast, color reproduction.