A display device includes a controller, a display processor, a resolution converter, and a display screen. The controller, in response to first request of setting a current signal source type to a first signal source type which is a type of a signal source for providing display data having a target resolution and a first definition, generates and transmits a first control signal corresponding to the first request. The display processor receives and forwards the first control signal from the controller. The resolution converter converts the initial display data into first display data having a target resolution and a first definition in response to the first control signal, and transmits the first display data to the display processor. The target resolution is greater than the initial resolution. The first definition is greater than a definition of display data obtained by stretching the initial display data and having the target resolution.