Experiment III: sensitivity of readability.
To compare the performance of halftone QR code with original QR code, we randomly selected 5 out of 91% successful results and corresponding original QR codes, then separately applied to images Gaussian noise with various amounts from 10% to 100%, Gaussian blur with kernel radius from 0.5 to 6 pixels, and scanned the code at tilted angle from 10 to 75 degrees. Each QR code was scanned by three users using four barcode readers. As shown in Figure 7((c)-(e)), the halftone
QR codes stop being functional under excessive setting of Gaussiannoise (40%), Gaussian blur (2 pixels) and viewing angle (40 degrees), while the original QR codes crash at Gaussian noise (80%), Gaussian blur (6 pixels) and viewing angle (60 degrees). In fact, this tradeoff allows our algorithm to create visual QR codes.