Hi Terence, thanks for including my alien QR in your blog post! I guarantee it reads perfectly (and quickly) in Optiscan, although I know others have issues. Error correction helps, but – as you say – getting the balance right between light and dark is essential. One complete failure of QR Code use recently was in a print piece for the Vatican – the QR Code colours were reversed to fit the ad better and so consequently didn’t read at all!