A time controller is able to convert and present the LCD display of gray levels within images with a brightness equal to that within the original images. The time controller alternates in operation between first and second modes of gamma correction, each for a specified time duration. In the first correction mode, the time controller corrects the original gray levels in a correction-positive manner and outputs first correction gray levels. In the second correction mode, the time controller corrects the original gray levels in a correction-negative manner, and outputs the second correction gray levels. The first correction gray level is equal to or larger than the second correction gray level, to correspond with original gray levels.