1. A method of searching for an image, the method comprising: determining whether a unique identifier exists in metadata of an input image to be searched for; when the unique identifier exists in the metadata, searching for an original image of having a same unique identifier with the input image in a target device; when the unique identifier does not exist in the metadata, extracting a characteristic value of the input image, and searching for the original image by comparing the extracted characteristic value with one or more characteristic values of one or more images stored in the target device, wherein the input image is an image edited or converted from the original image such that the input image is different from the original image, and the unique identifier has a unique value that is not changed while the original image is edited or converted.