Method for automatically generating an optical blend mask per projector, which blend mask is arranged in the beam path of a projector in a projection system comprising at least two projectors, including the following steps: - determining a geometrically distorted actual state of the projection system by a measurement, i.e., the capture of the real actual state of the projection system, - on the basis of the measurement, generating an ideal blending which would facilitate an absolutely error-free projection of a partial image by influencing the brightness of the image or video signals of the partial images, - ascertaining an individual distortion for each partial image to be projected by the projector, said distortion being caused by inaccuracies during the manufacture of a lens or of a plurality of lenses of a projector, by means of a front or back projection surface introduced in the beam path of the projector in a blend mask plane which is located in front of each projector at a location in the beam path of the respective projector at which the optical blend mask to be generated should be used, using patterns from which points are derived, wherein the alignment and the position of the front or back projection surface which is introduced within the blend mask plane is ascertained in relation to markers on a frame, which form a local reference coordinate system, and wherein the position of the points is determined in the local reference coordinate system, - calculating an optical blending for each partial image to be projected by the projector, wherein the ideal blending is positioned and/or transformed on the blend mask plane, wherein the ideal blending is adjusted to compensate for a blur in the beam path, wherein the optical blend mask to be generated is used in the blend mask plane and not in the focal plane of the projector, and wherein the ascertained individual distortion of the projector is applied to the calculated optical blending, - ascertaining data on the basis of the optical blending, and - generating the optical blend mask on the basis of the ascertained data. - determining a geometrically distorted actual state of the projection system by a measurement, i.e., the capture of the real actual state of the projection system, - on the basis of the measurement, generating an ideal blending which would facilitate an absolutely error-free projection of a partial image by influencing the brightness of the image or video signals of the partial images, - ascertaining an individual distortion for each partial image to be projected by the projector, said distortion being caused by inaccuracies during the manufacture of a lens or of a plurality of lenses of a projector, by means of a front or back projection surface introduced in the beam path of the projector in a blend mask plane which is located in front of each projector at a location in the beam path of the respective projector at which the optical blend mask to be generated should be used, using patterns from which points are derived, wherein the alignment and the position of the front or back projection surface which is introduced within the blend mask plane is ascertained in relation to markers on a frame, which form a local reference coordinate system, and wherein the position of the points is determined in the local reference coordinate system, wherein the alignment and the position of the front or back projection surface which is introduced within the blend mask plane is ascertained in relation to markers on a frame, which form a local reference coordinate system, and wherein the position of the points is determined in the local reference coordinate system, - calculating an optical blending for each partial image to be projected by the projector, wherein the ideal blending is positioned and/or transformed on the blend mask plane, wherein the ideal blending is adjusted to compensate for a blur in the beam path, wherein the optical blend mask to be generated is used in the blend mask plane and not in the focal plane of the projector, and wherein the ascertained individual distortion of the projector is applied to the calculated optical blending, wherein the ideal blending is positioned and/or transformed on the blend mask plane, wherein the ideal blending is adjusted to compensate for a blur in the beam path, wherein the optical blend mask to be generated is used in the blend mask plane and not in the focal plane of the projector, and wherein the ascertained individual distortion of the projector is applied to the calculated optical blending, - ascertaining data on the basis of the optical blending, and - generating the optical blend mask on the basis of the ascertained data.