1. A method for combining two images into a combined image, comprising: acquiring a first image comprising pixels with a computer system; acquiring a second image comprising pixels with the computer system; designating either the first or the second image as being a threshold image, and the other as being a non-threshold image, based on a predetermined designation criteria; segregating pixels in the threshold image into foreground pixels and background pixels according to a predetermined threshold criteria; applying an alpha value representing a degree of contribution for a merged image to each pixel of the threshold image, wherein a respective pixel alpha value represents a zero degree of contribution for the background pixels, and greater than zero degree of contribution for the foreground pixels; applying an alpha value representing a degree of contribution for a merged image to each pixel of the non-threshold image, wherein the alpha value for each pixel of the non-threshold image is chosen to represent a full degree of contribution minus the alpha value of a corresponding pixel in the threshold image; combining respective pixels in the threshold image with pixels in the non-threshold image to produce a combined image, the relative contribution of a threshold image pixel and non-threshold image pixel being defined by the appertaining alpha values of the pixels; and outputting the combined image via an output device.