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; an image processor configured to generate an X-ray image based on the electrical signal; and a controller configured to process the X-ray image 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.