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!