1. A method for generating a projection image from tomographic images ( 111 ), the method comprising the following steps: capturing (S 101 ) a plurality of stacked two-dimensional tomographic images ( 111 ) representing a tomographic volume; weighting (S 102 ) pixels of the stacked two-dimensional tomographic images ( 111 ) along a number of projection beams ( 109 ) through the tomographic volume with weighting factors chosen under a constraint that a sum of all squared weighting factors for each individual projection beam lies between a given lower limit and a given upper limit; and summing up (S 103 ) the weighted pixels along the number of projection beams ( 109 ) for generating the two-dimensional projection image.