The present technology allows for easily checking whether a moving part is in focus. A video signal at a first frame rate is acquired from a captured video signal at a second frame rate N times higher than the first frame rate. N is an integer larger than or equal to two. Each frame of the captured video signal at the second frame rate is filtered in horizontal and vertical high pass filter processes so that an edge signal is detected. An edge signal corresponding to each frame at the first frame rate is generated in accordance with the edge signal of each frame. Synthesizing the generated edge signal onto the video signal at the first frame rate provides a video signal for a viewfinder display.