Patent ID: 7807254

Claim:
A security feature for an identification document, the feature comprising: a base document layer, including a first image printed with a first ink having a first surface tension, the first ink being covert to a human viewer under normal, ambient lighting conditions, the first image bonding to the base document layer; and a personalized image relating to a bearer of the identification document printed over the first image, the personalized image comprising a second ink that is incompatible with the first ink the second ink having a surface tension which is higher than the first surface tension of the first ink, wherein the second ink does not wet out on the first image printed such that the personalized image does not bond to the first image but does bond to the base document layer in areas where the first image is printed and wherein the printed areas of the first image are embedded within the personalized image and become overt and visible to a human viewer upon printing of the personalized image.