first, we used a default value of λ = 0.0 to generate one hundred halftone QR codes and run the
manual scan procedure as in experiment I. We found that 91% of the results can be successfully read by all barcode readers, meaning that our representation model could handle large type of images with no difficulty. For the rest of 9% results which failed in one or more barcode readers, we regenerated results with λ = 0.3 and λ = 0.6, and repeated the experiment. We hypothesize that the readability of these results could be effectively improved as we increase the λ (see Figure 8). Figure 7(b) shows the average success rates against