1. An image processing device comprising: a face detector configured to detect a face based on a taken image; and an output processor configured to have a function to execute privacy-mask processing for privacy protection for an image of a face detected by the face detector or an image of a background of the face, wherein the output processor includes a function to output a first image of a face detected by the face detector and a first image of a background of the face which are each subjected to the privacy-mask processing, output a second image of the face detected by the face detector and a second image of the background of the face which are each not subjected to the privacy-mask processing, combine the first image of the face with the second image of the background to generate a combined image or combine the second image of the face with the first image of the background to generate a combined image, such that when the combined image of the face is subjected to privacy processing the privacy processing performed on the face of the combined image can be undone without use of the background of the combined image.