1. A method for combining automatically detected demographic, group, and behavior features of people in a retail transaction area with transaction data, comprising the following steps of: a) acquiring facial images of the people from first input images captured by at least a first means for capturing images, including a visual sensing device, b) determining demographic categories of the facial images to generate a demographic data, using at least a demographic feature extractor, c) acquiring person images from second input images captured by at least a second means for capturing images, including a visual sensing device, near the transaction area, d) determining shopping group membership of the people to generate group data from the second input images, e) analyzing the movement of the people for behavior analysis by determining checkout behaviors of the people based on analysis of the second input images by recognizing interactions of the people with merchandise in the transaction area, f) associating transaction data with the demographics data, the behavior analysis, and the group data, and wherein the analysis of the second input images comprises body orientation estimation of the people, proximity calculation between the people and checkout shelves, and foreground object analysis, in the transaction area, wherein the first means for capturing images comprises a face view camera that captures the facial images of the people waiting in the checkout queue for face detection, wherein the second means for capturing images comprises a top-down view camera that captures the top-down view and person images of the checkout queue for person detection, wherein the face view camera and the top-down view camera are placed and oriented so that the image positions of the facial images and the person images are translated into a common world-coordinate system, and wherein the steps are performed in a control and processing system that is connected to the means for capturing images.