#frameinterpolation

Correct settings when connecting the TV to a PC significantly affect the playback quality. Basically, they depend on the algorithm of video signal processing. Usually, modern LCD TVs of the middle price range provide a frequency of up to 100-200 Hz. An increase in frequency is achieved by interpolation of frames. But companies use different names for this technology. For example, this technology is called True Motion in LG TVs, Motion Plus in Samsung TVs, Perfect Natural Motion in Philips TVs or Real Cinema in Panasonic TVs.

Operation principle

The TV receives input signals with a frequency, for example, 50 Hz, forms an additional intermediate frame from two adjacent frames and then plays back all frames, including the newly formed one.

Accordingly, the frequency increases, for example, to 100 Hz. This process is called anti-aliasing and ensures smooth and realistic video playback. Interpolation algorithm reproduces incoming frames with a delay, calculating the offset difference between neighboring frames to create its own intermediate image. CPU calculates scene, object displacement, background and other parameters with the help of appropriate algorithms and creates frame on the basis of these parameters. It's designed to smoothing the transition between neighboring frames at the entrance. This effect becomes noticeable at panoramic shooting with offset of background. The intermediate frame reduces this offset between frames. Interpolation provides the smoother playback, increasing it by 2-4 times.

Playback with PC video card

PC has a video card with a HDMI yield. The maximum frequency of transmission for HDMI cable is 60 Hz in 1080p resolution. Most modern digital movies typically have a frequency ~ 24 frames / second. The video card of PC also generates an intermediate image with the help of video CPU and software. This process is as follows. PC increases a frequency with 24 Hz to 50 Hz. After that, the image is directed to the TV input. TV is trying increase the frequency up to 100 Hz. As a result, the image on the screen starts to "float". It accelerates, slows down or "hangs" for a second. Of course, viewing video in this mode is very inconvenient. The problem is double video processing. Processing algorithms on PC and TV are not synchronized that leads to a chaotic sequence of their work.

Decision

Turning off anti-aliasing in the TV at first glance seems like an obvious solution to this problem. But the TV creates an image with a frequency of 100 Hz, and the computer’s video card only provides up to 50 Hz. Thus, disabling an image processing on a computer is more efficient. This is done as follows. The auto-tuning function of the image frequency at the output of the player is switched. This option ensures that the output frequency matches the original video file frequency. In this mode, the player determines the frame rate at the input (24 Hz) and automatically converts the HDMI video output at this frequency. As a result, the TV receives a video stream at a rate of 24 frames per second without preliminary processing. The anti-aliasing mode on the TV provides image playback without jerks and braking. This method is great for video playback. But the interface and the program will work slowly because of switching the image frequency to 24 Hz. This setting is performed by the videoplayer (for example, the XBMC-player has this function) or using an autofrequency program.

Of course, the playback quality is one of the main criteria for choosing a TV. It, in turn, depends on the technical characteristics of the model and on the settings. Some of them are complex and require special equipment for calibration. But many basic settings are easily performed by the user themselves using the settings menu and test pattern. Optimum adjustment of TV settings significantly affects the image quality. Brightness, Sharpness and color / saturation are some of the basic parameters of the image.

Brightness

This value characterizes the maximum possible level of white in the center of the screen, is measured in candelas per square meter (1cd / mВІ = 1nit) and is one of the most important characteristics of a TV. It provides a comfortable viewing in any external lighting, for example, in daylight or electric lighting. A modern TV provides normal image quality with a minimum brightness of 250 cd / square meter or higher. This value should be directly proportional to the screen diagonal. For example, 250 cd / square meter is enough for a 19" model, but a 36" TV requires already 500 cd / square meter. The backlight brightness behind of crystals does not affects on the image brightness. The image brightness depends on the crystals quality, their location and from correct adjust of polarizing filters. Thus, the electronics significantly affects on value of this parameter. Brightness setting regulates primarily black level. Special pattern test image is intended for the correct setting this parameter. All gradations of black should be clearly distinguished. The left diagram corresponds to the correct brightness setting, and the right diagram shows a non-optimal setting of this value.

Sharpness

Correct setting of this parameter provides an equally sharp image for any viewing distance. Sharpness test image is designed for adjustment of this parameter. Setup is as follows: - the user is located on a comfortable for him the distance from TV; - the Sharpness test image is displayed on the TV screen.

- its value increases to the maximum or until the appearance of artifacts due to excessive sharpness, which manifests itself as bright halos around objects and thickening for fine lines; - the value is reduced to the disappearance of artifacts. This sharpness is optimal.

Saturation

The correct setting of this parameter is difficult without a special device for calibration. However, this can be done with the help of photographs. It's carried out by the following algorithm. High-quality photos of nature with the different shades of green are displayed on the TV screen.

Green color is the most preferred due to maximum sensitivity of the eyes to it. Additionally, the many TVs reproduce this color with a maximum distortion. Next, the color / saturation value is adjusted before the maximum image realism. User can also to adjust this parameter with the help of high-quality people photos. In this case, the natural skin tone is the criterion of the settings correctness.

Motion-Compensated Frame Interpolation (MCFI)

This technology is designed to smooth out the playback of dynamic scenes and is based on the formation of intermediate frames.

Many consumers pay attention to the differences in the playback quality of TVs in stores. This is especially noticeable during simultaneous work of several TVs on one channel. Unfortunately, modern TV manufacturers primarily are interested in increasing sales. Therefore, the optimal pre-settings are not a priority for some companies. Manufacturers often try to present in their TVs maximally "bright blue" and "red" colors, increasing the brightness of these colors. Marketers know that the buyers majority choose the brightest TVs or models with maximally deep color. However, the most TVs provide the similar playback quality when properly setting. This factor can be useful in choosing the optimal TV.

Main settings

The calibration provades the maximum correct image playback. This method uses a reference image at the TV input. The values of reference image parameters are compared with the image on the screen. Complex Delta E characterizes the deviation degree from standard color. For example, Delta E = 0 corresponds to the ideal setting. The reference colors are very deep, bright and saturated. A calorimeter provides a measure of the color temperature of the output signal. Specialist achieves of the images identity on the screen with reference colors during the calibration process. Only top models usually provide full calibration. Typically, Delta E value after calibration is 2-3. The human eyes do not perceive such distortion. However, this calibration is laborious, requires knowledge and equipment. The TVs are adjusted before the maximum possible identity to international standards. The TV must minimally to distort the original content that is always created on basis of standards or recommendations. Correct playback of the sky at sunset, skin color of actor and the image details provides realness. Abbreviations PAL, NTSC or HDTV are designation of these standards. They contain requirements and recommendations to the video signal parameters and the allowable values of various image parameters. Most of the standards are outdated after the HDTV emergence. Today OLED TVs provide maximum color gamut.

Main technical values