METHOD AND APPARATUS FOR READING INVISIBLE MESSAGES

An apparatus and method for reading invisible messages is disclosed. Two light sources impinge upon a surface upon which a luminescent message is located. The first light excites the luminescent message, which luminesces and emits a luminescent light. The luminescent light is received by an image sensor and is converted into a first electric signal. The second light has wavelengths substantially similar to the luminescent light, which reflects from the surface and is received by an image sensor and converted to a second electric signal. The first and second signals are processed to compensate for local variations in the reflectivity of the surface.