Frame rate control

Frame rate control (FRC) is a method for achieving greater color depth in TFT LCD displays.

Older TN panels represented colors using only 6 bits per RGB color, or 18 bit in total, and were unable to display the 16.78 million color shades (24-bit truecolor) that display devices like graphics cards, video game consoles, tablet computers and set-top boxes can output. Instead, they could use a dithering method that combines adjacent pixels to simulate the desired shade. As of 2021, most TN panels are capable of displaying 24-bit color without any form of dithering.

FRC is a form of temporal dithering which cycles between different color shades with each new frame to simulate an intermediate shade. This can create a potentially noticeable 30 Hz (half frame rate) flicker. FRC tends to be most noticeable in darker tones, while dithering appears to make the individual pixels of the LCD visible.[1] TFT panels available in 2020 often used FRC to display 30-bit deep color or HDR10 with 24-bit color panels.[2][3]

This method is similar in principle to field-sequential color system by CBS and other sequential color methods such as used in Digital Light Processing (DLP).

In the demonstration video green and cyan-green are mixed both statically (for reference) and by rapidly alternating. A display with a refresh rate of at least 60hz is recommended for this video. Pausing the video shows that the perceived color of the bottom-right square during playback is different from the color seen in any individual frame. In a monitor that uses FRC, the alternating colors would be more similar, further reducing the flicker effect.