1. An image processing device for generating images from multiple viewpoints, by shifting coordinates of pixels in an original image, in order to provide depth indicated by a depth image composed of a pixel region defined by a plurality of pixels, a value of each of the pixels in the depth image indicating the depth of a corresponding one of the pixels in the original image, the image processing device comprising a memory and a processor, the processor being configured to execute: conversion processing to convert the depth image by searching within the pixel region composing the depth image for edge pixels that constitute an edge of an object and shifting, in a predetermined direction, coordinates of the pixels in the depth image that are surrounded by the edge pixels; generation processing to generate a viewpoint image from a different viewpoint than the original image by calculating a parallax that provides the depth indicated by the depth image converted by the conversion processing and shifting the coordinates of the pixels in the original image by a number of pixels corresponding to the parallax; and interpolation processing to interpolate an occlusion, occurring due to pixel shifting, in the generated viewpoint image, wherein: the conversion processing includes accepting a level selection from a user when the depth image is converted, and changing the number of pixels corresponding to the parallax according to the level selection, background pixel regions of the original image appear, due to the conversion processing, at a side to a left of the occlusion and a side to a right of the occlusion in generated viewpoint images, one of the background pixel regions between the edge of the object and the occlusion having a width according to the parallax, and the interpolation processing includes linear interpolation using pixel values of the background pixel regions located at the side to the left of the occlusion and the side to the right of the occlusion.