An object is to provide a semiconductor device with low power consumption. The semiconductor device includes a controller, a register, and an image processing portion. The image processing portion has a function of taking image data from a frame memory and a parameter from the register and processing the image data by using the parameter. The frame memory has a function of retaining the image data while power supply is stopped. The register has a function of retaining the parameter while power supply is stopped. The controller controls power supply to the register, the frame memory, and the image processing portion. The register includes first and second scan chain registers. The first scan chain register stores a parameter related to a first display region. The second scan chain register stores a parameter related to a second display region. A parameter is changed by loading of data of the first or second scan chain register.