The invention relates to an image generation apparatus for generating an image of an object. An image providing unit (11, 16) provides a first image of the object and a second image of the object, wherein the first image has a smaller noise level than the second image. A display window providing unit (12) provides a display window being indicative of the range of image values shown on a display (14), and a combining unit (13) generates a combination image by combining the first image and the second image depending on the window width of the provided display window. This allows considering the influence of the display window on the noise appearance. Thus, by taking into account the first image and the second image having different noise levels and the provided display window, a combined image can be generated, which has an improved noise appearance.