Disclosed is a method of finding a reference object within a coded object having a plurality of regions. Each region has a plurality of subregions, and at least a majority of a first one of the subregions has a different color from a second one of the subregions. The reference object has a known relative position to other objects within the coded object so that the reference object is utilizable to locate the other objects within the coded object. A first one of the subregions within a selected one of the regions within the coded object is selected. A first region and a second region within the coded object are also selected. The selected first and second region form a plurality of subregion pairs. Each subregion pair includes a subregion from the seleced first region and a subregion from the selected second region. Luminosity values of the subregions within each subregion pair are compared. It is determined whether the selected subregion is the reference object based on the comparisons of the luminosity values for each subregion pair.