To efficiently extract a partial video image with designated lightness without the use of a special set for a photographed scene.

An AE circuit 102 adjusts exposure based on an image signal or a detected area that is designated by a detection area management section 103 among images received by a video image input section (image pickup means) 101 and generates exposure information denoting the result. A computer terminal 200 converts the exposure into image lightness information and discriminates whether or not the partial area is to be extracted based on the obtained lightness information. An image corresponding to the partial area discriminated to be extracted through the discrimination above among the images received by the image pickup means 101 is pasted on output video data and the resulting data are outputted.