A method for correcting a shading in a digital image of a three-dimensional observation object obtained by at least one image sensor of an optical observation device is provided. The three-dimensional observation object is illuminated by illumination light and an intensity distribution, and an inhomogeneity in an image brightness is present in the digital image of the three-dimensional observation object. The method includes ascertaining a topography of the three-dimensional observation object, correcting the inhomogeneity in the image brightness of the digital image based on the topography of the three-dimensional observation object and the intensity distribution of the illumination light. In addition, an optical observation system is provided to perform the method.