A method of video analysis may comprise tracking a state of each target in a video through multiple frames of said video, each state indicating a visibility condition of a target. Each of the fins includes a main body. The lamp assembly may include a camera. The printer unit develops the input image file, prints the corresponding image, and outputs it. A relaxation time when charge is stored in the display element of the pixel and other capacitors connected to the display element in parallel is focused on, and the voltage applied between the source and the drain of the transistor in the writing period is suppressed by changing the video signal applied to the signal line step by step and finally setting it at the desired level.