1. A computer-implemented method for generating a composite image, comprising a decorative image having a plurality of pixels, a bar code having a plurality of cells, and one or more filter patterns; wherein the composite image visually approximates the decorative image, yet the composite is machine-readable by a scanner capable of reading the original bar code, and the composite encodes the same data as the original bar code; the method comprising: positioning the bar code to coincide with some region of the decorative image; assigning one or more filter patterns to each bar code cell; and processing each pixel within the decorative image, thus forming the composite image; the processing of pixels within the decorative image comprising, for each pixel position: retrieving the pixel color in the decorative image at that pixel position; retrieving the values of all filter patterns at that pixel position; and updating the pixel color by applying the set of filter pattern values.