Method to adjust the print quality of print images in an electrophoretic digital printer

In a method to adjust print quality of print images in an electrophoretic digital printer with at least one print group, the print group generates charge images of the print images. The charge images are developed with a developer station into toner images using liquid developer having carrier fluid and toner. The toner images are transfer-printed onto a carrier medium in a transfer station. A first control marking is generated on the recording medium with elements of the first control marking being aligned transverse to a printing direction. A shape of the elements of the first control marking is measured to generate a first measurement signal. The first measurement signal is compared with a predetermined nominal value, and given a difference, an adjustment signal is generated via which an amount of the carrier fluid in the liquid developer is modified so that the first measurement signal approaches the predetermined nominal value.