1. A method, comprising operating a computer processor to perform operations comprising: ascertaining a respective score for each of multiple positions of a graphic object in a background image, wherein the ascertaining of each of the scores comprises evaluating a function that depends on characteristics of the graphic object and characteristics of the background image and provides a quantitative assessment of a placement of the graphic object at the respective position in the background image, the ascertaining comprises determining values of color contrast between the graphic object and the background image, and the ascertaining further comprises determining the scores from the determined color contrast values; selecting one of the positions based on the scores; and producing an output image, wherein the producing comprises superimposing the graphic object on the background image at the selected position.