1. An X-ray imaging apparatus comprising: an X-ray source configured to transmit X-rays; an X-ray detection assembly configured to detect the X-rays, and to convert the detected X-rays into an electrical signal; a controller configured to process an X-ray image generated based on the electric signal by changing shades of the X-ray image, and set a region of non-interest of the X-ray image based on the X-ray image and the processed X-ray image, wherein the controller is configured to perform, based on a threshold value, binary imaging on the processed X-ray image having the changed shades, and set a higher intensity region of the processed X-ray image as the region of non-interest in the X-ray image, and wherein the threshold value corresponds to an intensity value of a position having a maximum gradient in the X-ray image.