g-band image of NGC 4418 from the KiDS archive (Kuijken et al. 2019) illustrating the internal structure of the outer disk before (top) and after (bottom) subtraction of a disk model (middle). The images are smoothed with a σ = 3 pixels (1.2″) Gaussian kernel to improve the signal-to-noise ratio. The difference image reveals an asymmetric feature, indicated by the arrow, that has the properties of a one-sided tidal tail produced by a minor interaction. From the inside out, the contour levels in the middle panel are at 80%, 60%, 40%, 20%, 10%, and 5% of the surface brightness of the innermost contour. The central pixels in NGC 4418 are excluded from the model fit due to dust structures at this location. The features near the center of the galaxy in the bottom panel are due to undersubtraction of the smooth model from the centrally complex, clumpy data.