Experimental results have been obtained to assess aerodynamic effects on droplet sizes and nonlinear wave shapes for low-speed jets with forced perturbations. One-dimensional digital image processing used previously with anamorphic optics is successfully adapted to measurement of droplet images from circularly symmetric optics. These digital image processing techniques are demonstrated for automated subpixel edge detection, thereby yielding unambiguous quantitative information such as droplet sizes and leave shape in an automated manner. The imaging and signal processing techniques and their rigorous calibration are discussed in detail. The techniques have been used to assess the influence of excitation frequency and aerodynamic influence (from the gas phase) on droplet size and jet behavior. Results are also compared to those from previous experiments and from theoretical calculations using boundary-element methods.