Frame rate control (FRC) is a method for achieving higher color quality in low color resolution display panels such as TN+film LCD.
Most TN panels represent colors using only 6 bits per RGB color, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available from graphics cards. Instead, they use a dithering method that combines adjacent pixels to simulate the desired shade.
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 flicker. FRC tends to be most noticeable in darker tones, while dithering appears to make the individual pixels of the LCD visible.
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).
8 bit TN+film panels with dithering are sometimes advertised as having "16.2 million colors".