Method for operating a display device of a motor vehicle, wherein the display device is arranged to output a digital image on a transparent display surface of the motor vehicle, the method comprising the steps: - capturing, by a first sensor device, a viewing direction of a user situated in an inner space of the motor vehicle toward the display surface (10, S1), - determining, by a control device, in dependence on the captured viewing direction, a display parameter of the digital image (26, S2), which parameter specifies an absolute visual form of the digital image and in so doing takes account of the fact that from the viewing direction of the user on the absolute visual form of the digital image a relative, perspective-dependent form of the digital image results, so that the relative, perspective-dependent form corresponds to an intended form of the digital image, - producing the digital image by the control device (24, S3) in dependence on the determined display parameter and transmitting the digital image to the display device, and - output of the digital image on the display surface (10, S4), the method comprising the step: - capturing, by a second sensor device of the motor vehicle, the environment of the motor vehicle (14, S5), and characterised by the steps carried out by the control device: - on the basis of the captured viewing direction, determining the environment of the motor vehicle (14, S6) that is visible to the user through the display surface, - determining a real object in the environment that is visible to the user and an outline and colour of the real object using sensor data of the second sensor device (28, S7), and - depending on the detected outline and colour of the real object, adjusting the display parameter, so that the absolute visual form of the digital image has an outline that corresponds to the outline of the real object and a colour that differs from the colour of the real object, - depending on a connection line between an eye of the user and the real object lying through the transparent display surface, determining a point of intersection of the connection line with the transparent display surface (10, S9), - adjusting the display parameter, which describes the determined point of intersection as a position of the digital image on the display surface, to mark on the display surface the real object that is visible to the user, and - determining a perspective from which the user sees the digital image; wherein the determination of the display parameter takes into account the determined perspective and wherein the display parameter describes a perspective equalisation of the digital image, so that the digital image can be viewed from an intended perspective. - capturing, by a first sensor device, a viewing direction of a user situated in an inner space of the motor vehicle toward the display surface (10, S1), - determining, by a control device, in dependence on the captured viewing direction, a display parameter of the digital image (26, S2), which parameter specifies an absolute visual form of the digital image and in so doing takes account of the fact that from the viewing direction of the user on the absolute visual form of the digital image a relative, perspective-dependent form of the digital image results, so that the relative, perspective-dependent form corresponds to an intended form of the digital image, - producing the digital image by the control device (24, S3) in dependence on the determined display parameter and transmitting the digital image to the display device, and - output of the digital image on the display surface (10, S4), - capturing, by a second sensor device of the motor vehicle, the environment of the motor vehicle (14, S5), - on the basis of the captured viewing direction, determining the environment of the motor vehicle (14, S6) that is visible to the user through the display surface, - determining a real object in the environment that is visible to the user and an outline and colour of the real object using sensor data of the second sensor device (28, S7), and - depending on the detected outline and colour of the real object, adjusting the display parameter, so that the absolute visual form of the digital image has an outline that corresponds to the outline of the real object and a colour that differs from the colour of the real object, - depending on a connection line between an eye of the user and the real object lying through the transparent display surface, determining a point of intersection of the connection line with the transparent display surface (10, S9), - adjusting the display parameter, which describes the determined point of intersection as a position of the digital image on the display surface, to mark on the display surface the real object that is visible to the user, and - determining a perspective from which the user sees the digital image;