1. An image converter, comprising an image converting unit and a determining unit, wherein the image converting unit sequentially acquires frame image groups each including one or a plurality of frame image(s) from original image data that is constituted by these frame image groups, and outputs the frame image(s) included in each of the acquired frame image groups by converting an image quality of the frame image(s) based on a result of determination by the determining unit, thereby to generate a foreign-device-use image data that is constituted by the frame image groups including the frame image(s), the determining unit determines whether it is necessary to retain the frame image(s) of each frame image group at a first image quality or not based on whether the frame image(s) of the frame image group satisfies/satisfy a predetermined condition or not, in a case where the determining unit determines that it is necessary to retain the frame image(s) of the frame image group at the first image quality, the image converting unit outputs the frame image(s) of the frame image group at the first image quality, and in a case where the determining unit determines that it is unnecessary to retain the frame image(s) of the frame image group at the first image quality, the image converting unit outputs the frame image(s) of the frame image group at a second image quality.