The passport photographs of the future could turn out to be more than just another pretty picture if a new computer technique developed by Israeli scientists catches on. Researchers at Ben-Gurion University, in Israel, have invented a way to hide information such as a fingerprint or signature in color images. They believe this could improve passport safety or be used to produce product bar codes  or designs that cannot be seen. "The papers can be faxed, scanned  and reprinted without hidden data disappearing," New Scientist magazine said last week. Joseph Rosen and a team of scientists worked out the new instrument by creating a mathematical model. The model turns a fingerprint or signature into a series of numbers which are used to shape the dots that make up a color picture. "Each dot can be forced out of the usual place slightly without noticeably changing the final appearance of the image," the magazine said. Several images that can be hidden in a single picture are scanned into a computer which does the work. The hidden images or fingerprints cannot be shown until the picture is scanned again. The computer rebuilds the fingerprint by measuring the displacement of the dots in the picture. The magazine said that if he model is used for passport checkpoints the picture can be unscrambled  to show the fingerprint or signature and checked against the person holding the passport. The researchers are now working on a handheld, and instrument which could make unscrambling the hidden information easier. The new passport photos will probably contain all EXCEPT   _  .
one's picture one's fingerprint one's signature one's blood type