1. A user device comprising: a storage configured to store data; and a processor configured to recognize a person included in an image captured by the user device or received by the user device from an external source, determine a degree of closeness in a relationship between the recognized person and a user who is registered as an owner of the user device based on whether at least one picture of the recognized person is stored on the storage, determine that the degree of closeness is lower than a predetermined level in response to any picture of the recognized person not being stored on the storage, determine that a location where the image is captured is a photographing restricted location in response to the image comprising a sign indicating that photography is prohibited, change a part of the image corresponding to the recognized person to be unrecognizable in response to the degree of closeness being lower than the predetermined level, and replace the image with another image in response to the location being determined as the photographing restricted location.