A code is displayed on a screen with a first set of indicia, the code designed to be read only by a computer system. A second code is displayed only when it is determined that the code is being read. This determination is made by an optical sensor, such as a camera, detecting a particular wavelength of light above a threshold, the wavelength associated with an expected reader device. While the particular wavelength is detected the second code is displayed. Once the light is no longer detected, the display reverts back to the first code. In this manner, the second code, such as a barcode to be read is only displayed while the barcode is actually being read, but is otherwise hidden from view. The entire process can take place in under a second or in a fraction of a second, such as 1/10th of a second or less.