1. A method of acquiring information about content, the method comprising: receiving a video signal from an external apparatus connected to an image display apparatus; receiving comparative data from a server system; detecting an on screen display (OSD) image from an image that is produced using the received video signal; classifying the detected OSD image according to at least one of a location where the detected OSD image is to be displayed on the image display apparatus and a type of the detected OSD image; identifying an object included in the OSD image using the classification of the detected OSD image to increase the accuracy of the identifying the object; producing a descriptor that describes the features of the identified object; and collecting the information about content by using the identified object and by comparing the descriptor with the received comparative data.