The present invention embodies a technique, referred to as Secure QR Codes, which not only provides aesthetically enhanced QR codes but also allows for security. It can embed a standard black and white QR code, referred to as a public QR code, and a secret QR code, both into a secure QR code. The secure QR code produced is composed of colored cells. The public black and white QR code must first be, either aesthetically enhanced into an enhanced colored QR code, or transformed into a colored QR code with cells of uniform color obtained by transforming each of the black and white cells of the public QR code into cells that takes a color from a subset of possible colors, such that the luminance of each colored cell approximates accurately the black or white luminance values of the public QR code.