3. The apparatus according to claim 1 , further comprising: a fourth extraction unit configured to extract one or more keywords included in the region of interest; and a display unit configured to display the keywords on the display screen.
3. The apparatus according to claim 1 , further comprising: a fourth extraction unit configured to extract one or more keywords included in the region of interest; and a display unit configured to display the keywords on the display screen. 4. The apparatus according to claim 3 , further comprising: a retrieval unit configured to retrieve, when a keyword is selected from the keywords by the user, information relating to the keyword to output a retrieval result; and a retrieval result display unit configured to display the retrieval result on the display screen.