1. A system for measuring visibility, the system comprising: means for determining a lighting condition for an image; means for calculating a visibility based on the image; and means for adjusting the means for calculating based on the lighting condition, wherein the means for adjusting selects any one of: a set of visibility calculations for a daytime lighting condition, a set of visibility calculations for a nighttime lighting condition, or a set of visibility calculations comprising at least one calculation for a daytime lighting condition and at least one calculation for a nighttime lighting condition according to the lighting condition, and wherein the means for calculating calculates the visibility using the selected set of visibility calculations.