1. A method for an electronic device to detect an overlay area within an image, the method comprising: defining, by the electronic device, first and second areas within the image, the first and second areas non-overlapping; calculating, by the electronic device, an alpha-blended value of a mean color value of the second area with an overlay color value; and if a mean color value of the first area is closer to the alpha-blended value than it is to the mean color value of the second area, then defining an overlay area comprising at least one pixel within the first area, wherein the method is further performed separately on a first image, and on a second image, where the second image is a temporally averaged image, the method further comprising: determining a common overlay area based on an intersection of the overlay area for the first image and the overlay area for the second image.