We present a quantitative study of the simultaneous effects of surface topography and friction in atomic force microscopic imaging of octadecyltriethoxysilane-on-glass self-assembled monolayers, patterned by illumination with ultraviolet radiation through a mask. The ultraviolet light leaves a similar to 1 nm deep topographic depression in the exposed areas, and produces larger surface-tip friction which can be the dominant contribution to the apparent topography.