Designed to determine a number of frames of data for acquisition from video data on the basis of image quality setting data that allows image quality to be set for an image output by an image output device; and to acquire from the video data the determined number of frames of data, and synthesize the acquired number of frames of data to generate image data representing tones of an image by means of a multitude of pixels. Since image data can be generated by synthesizing frames of data in a number appropriate to the image quality of the output image, the process of generating image data representing a still image can be performed efficiently, and a still image derived efficiently.