5. A computer implemented method for replacing an existing text string within an image with a personalized text string to generate a natural text-rendered image, comprising: identifying a location and region within the image containing the existing text string to be replaced; deriving selected features from the existing text string; determining a 3D geometry of a surface upon which the existing text string has been rendered based on one or more of the selected features; determining a normal vector of the surface; erasing the existing text string; receiving the personalized text string; incorporating the personalized text string into the image to appear as if it is rendered onto the surface in place of the previously existing text string according to the estimated 3D geometry; and outputting the natural text-rendered image; wherein deriving the selected features comprises: segmenting the existing text string from a background of the image; and deriving the existing text string edges; wherein a binary search algorithm is employed to establish a predetermined threshold based upon one that produces the largest number of connected components of the existing text string edges.
8. The method of claim 5 wherein identifying the location and region is performed automatically via analysis of the image.