An image processing apparatus comprising: a user input interface configured to receive a user input; a storage configured to store a plurality of user IDs previously registered by a plurality of users and a database for biometric information of the plurality of users, the database comprising a plurality of records, wherein each record has an assigned system ID provided by the image processing apparatus, the system IDs being for distinguishing between the records in the database, wherein the database further comprises a content viewing history of the image processing apparatus by the user corresponding to the biometric information; and a signal processor configured, when an event occurs to identify a current user, to process: to identify whether a user ID input by the user input is authenticated based on the plurality of user IDs registered and stored in the storage, based on the user ID input by the user input being authenticated, to provide a first preset service corresponding to the authenticated user ID, and based on the user ID input by the user input not being authenticated, to retrieve a system ID from the database based on biometric information of the current user acquired by the user input interface and content viewing history of the image processing apparatus, and to provide a second preset service corresponding to the retrieved system ID, wherein, if the system ID cannot be retrieved based on the biometric information of the current user and the content viewing history of the image processing apparatus, to determine the current user as a new user, generate a new system ID and store the new system ID, the biometric information of the current user and the content viewing history of the image processing apparatus in the database, and the controller acquires the biometric information and the content viewing history with respect to the current user at the identifying event, and wherein the controller identifies the current user by comparing the acquired biometric information and the content viewing history with the biometric information and content viewing history in the database, and by retrieving the record in the database with the biometric information and content viewing history having a highest similarity with the acquired biometric information and the content viewing history. a user input interface configured to receive a user input; a storage configured to store a plurality of user IDs previously registered by a plurality of users and a database for biometric information of the plurality of users, the database comprising a plurality of records, wherein each record has an assigned system ID provided by the image processing apparatus, the system IDs being for distinguishing between the records in the database, wherein the database further comprises a content viewing history of the image processing apparatus by the user corresponding to the biometric information; and a signal processor configured, when an event occurs to identify a current user, to process: to identify whether a user ID input by the user input is authenticated based on the plurality of user IDs registered and stored in the storage, based on the user ID input by the user input being authenticated, to provide a first preset service corresponding to the authenticated user ID, and based on the user ID input by the user input not being authenticated, to retrieve a system ID from the database based on biometric information of the current user acquired by the user input interface and content viewing history of the image processing apparatus, and to provide a second preset service corresponding to the retrieved system ID, to identify whether a user ID input by the user input is authenticated based on the plurality of user IDs registered and stored in the storage, based on the user ID input by the user input being authenticated, to provide a first preset service corresponding to the authenticated user ID, and based on the user ID input by the user input not being authenticated, to retrieve a system ID from the database based on biometric information of the current user acquired by the user input interface and content viewing history of the image processing apparatus, and to provide a second preset service corresponding to the retrieved system ID, wherein, if the system ID cannot be retrieved based on the biometric information of the current user and the content viewing history of the image processing apparatus, to determine the current user as a new user, generate a new system ID and store the new system ID, the biometric information of the current user and the content viewing history of the image processing apparatus in the database, and the controller acquires the biometric information and the content viewing history with respect to the current user at the identifying event, and wherein the controller identifies the current user by comparing the acquired biometric information and the content viewing history with the biometric information and content viewing history in the database, and by retrieving the record in the database with the biometric information and content viewing history having a highest similarity with the acquired biometric information and the content viewing history.