1. A method for determining a navigation image configured to display features of a region of interest of a patient, the method comprising: recording a first X-ray image and a mask image with an X-ray device; determining, by the X-ray device, a first subtraction image by subtracting the mask image from the recorded first X-ray image; recording a second X-ray image with the X-ray device; determining, by the X-ray device, a second subtraction image by subtracting the mask image or a further mask image from the recorded second X-ray image; determining, by the X-ray device, the navigation image by superimposing the first subtraction image and the second subtraction image; and outputting the navigation image on a display device, wherein at least one of the subtraction images is preprocessed before the superimposition by transfer from a gray-value space into a color space that is different from a color space of the other subtraction image, wherein the navigation image is determined in color, and wherein dynamics of at least one of the subtraction images are compressed.