1. A method of verifying whether a product label is genuine or counterfeit which comprises: producing a counterfeit-proof label having an invisible universal product code by printing the code from a plurality of discrete views of the code on the photo chromogenic layer of a lenticular material, with each lenticule having a optical center, said printing being arranged so that at least a portion of the views of the code is printed at a pre-calculated optical blind angle in relation to the optical center of the lenticules at the normal viewing distance of the label; and viewing a label purporting to be a label for the genuine product through a digital camera having a viewing screen, said camera being configured to take a close up view of the code on label so that the invisible code can be viewed on the screen of the camera to determine if it matches the genuine code for the product.