1. An image editing device, for editing a combined photographic image formed by combining a plurality of images, comprising: an image compression section for carrying out lossy compression on the images in accordance with image quality control parameters for controlling degree of variation in image quality; an image expansion section for expanding a combined photograph, that has been formed by combining the plurality of images and then compressed by the image compression section, and expanding compressed images resulting from subjecting the plurality of images to image compression by the image compression section; a combined photograph editing section for carrying out editing of the combined photograph using the combined photographic image and the images that have been expanded by the image expansion section; and an image quality control parameter calculating section, for calculating image quality control parameters for combined photograph data that has been edited by the combined photograph editing section, in accordance with first image quality control parameters for when creating the combined photograph, and second image quality control parameter for when creating the compressed image, wherein in the case where a combined photograph that has been edited by the combined photograph editing section is subjected to image compression by the image compression section, the image quality control parameters that have been calculated by the image quality control parameter calculating section are used.