Opacity maps are, besides gaze plots and heatmaps, a graphical representation of eye tracking study results. They demonstrate which areas of a website are viewed more often or for a long time by one or several participants. Thereby, the image of the website is obscured by a black shadow. The more often or the longer an area has been looked at, the more transparent the shadow gets. If an area was not fixated at all, it is black on the opacity map. This enables to quickly identify which areas of the website were seen by participants of the eye tracking study. Opacity maps are the reverse of heatmaps.