A display apparatus comprising: a display; a tuner configured to receive a broadcast signal; a user input device configured to receive a user command; and at least one processor configured: to process the broadcast signal received from the tuner, to control the display to display a moving video image comprising a plurality of image frames based on the processed broadcast signal, in response to receiving the user command for displaying a graphical user interface from the user input device while the moving video image is displayed, to obtain an image frame from among the plurality of image frames, to divide the obtained image frame into a plurality of sections (351, 361), to identify brightness values in each of the plurality of sections based on red, green, and blue values of pixels in each of the plurality of sections, to adjust horizontal widths in each of the plurality of sections based on the identified brightness values in each of the plurality of sections, to apply blur filtering to the plurality of sections having the adjusted horizontal widths, and to control the display to display the GUI to be overlaid on a background image comprising the plurality of sections to which the blur filtering is applied, wherein the background image is a full screen image. a display; a tuner configured to receive a broadcast signal; a user input device configured to receive a user command; and at least one processor configured: to process the broadcast signal received from the tuner, to control the display to display a moving video image comprising a plurality of image frames based on the processed broadcast signal, in response to receiving the user command for displaying a graphical user interface from the user input device while the moving video image is displayed, to obtain an image frame from among the plurality of image frames, to divide the obtained image frame into a plurality of sections (351, 361), to identify brightness values in each of the plurality of sections based on red, green, and blue values of pixels in each of the plurality of sections, to adjust horizontal widths in each of the plurality of sections based on the identified brightness values in each of the plurality of sections, to apply blur filtering to the plurality of sections having the adjusted horizontal widths, and to control the display to display the GUI to be overlaid on a background image comprising the plurality of sections to which the blur filtering is applied, wherein the background image is a full screen image. to process the broadcast signal received from the tuner, to control the display to display a moving video image comprising a plurality of image frames based on the processed broadcast signal, in response to receiving the user command for displaying a graphical user interface from the user input device while the moving video image is displayed, to obtain an image frame from among the plurality of image frames, to divide the obtained image frame into a plurality of sections (351, 361), to identify brightness values in each of the plurality of sections based on red, green, and blue values of pixels in each of the plurality of sections, to adjust horizontal widths in each of the plurality of sections based on the identified brightness values in each of the plurality of sections, to apply blur filtering to the plurality of sections having the adjusted horizontal widths, and to control the display to display the GUI to be overlaid on a background image comprising the plurality of sections to which the blur filtering is applied, wherein the background image is a full screen image.