Device and method for applying flowable material to a substratum that can be rotated about an axis of rotation

A method for applying flowable material onto a substrate that is rotatable about an axis of rotation, according to predetermined image data which are stored in a first memory as pixels or vectors of a specific Cartesian coordinate system, the method comprising:

• determining special polar coordinate grid points comprising a subset of polar coordinate grid points of a specific polar coordinate grid, wherein the specific polar coordinate grid comprises an origin, concentric circles around the origin having a predetermined circumferential distance from one another, and rays extending from the origin and having a predetermined angular distance from one another, each intersection of a circle and a ray defining a polar coordinate grid point, and wherein said subset of polar coordinate grid points determined to be the special polar coordinate grid points comprises fewer polar coordinate grid points on each circle as the circles approach the origin such that a greatest number of special coordinate grid points are located on a circle farthest from the origin and a fewest number of special polar grid points are located on a circle closest to the origin,
• transforming the special polar coordinate grid points into coordinates of the specific Cartesian coordinate system,
• comparing the obtained Cartesian grid points to the pixels or the vectors of the image file, and
• applying material droplets of the flowable material onto the substrate by means of a printing head which has a plurality of nozzles arranged at a nozzle distance from one another, wherein the nozzles of the printing head are controlled in such a way that the nozzles only discharge material droplets when a position of the nozzles relative to the substrate corresponds to a position of a special polar coordinate grid point at which the comparison yields a correspondence.