Quantifying optical and mechanical contributions to dot gain

Abstract The origin of dot gain comes from two primary contributions: optical and mechanical, and therefore two functions describing these contributions have been tested. These contributions are reflected in the asymmetric shape of the Line Spread Function (LSF), which is a critical parameter for analyzing the quality of printed images. This paper uses a robust iterative method to fit LSF curves, incorporating multiple single peak functions to increase measurement accuracy and enhance understanding of the phenomenon. High correlation results demonstrate the plausibility of separating these contributions and determining their percentage share within the profile. Optical dot gain, modeled using a Lorentzian function, accurately reflects its dependence on substrate properties. Mechanical dot gain, on the other hand, is described by a Gaussian function, capturing its link to printing techniques. The high correlation (R > 0.97) between experimental and modeled data validates the robustness of this method, enabling precise determination of the percentage share of each component. The results indicate that optical dot gain contributes approximately 30 % of the total, a much larger share than previously assumed. This highlights the importance of substrate selection and treatment in achieving print quality. In the context of electrostatic printing, a third, previously undetected contribution was identified. Although minor, this additional mechanical component (Gauss1) is reproducible and directly linked to the operational state of the printing machine, adding complexity to the dot gain phenomenon.