斜向網點雙重加密之研究

Abstract

本研究主要目的是透過斜向網點雙重加密的設計，應用於有價證券（郵票）中。藉由數位半色調技術，將連續調影像轉換為斜向網點的半色調影像，利用擬隨機亂數的方式，將八位元編碼轉換的資訊，隨機加入於影像資訊中，並將準備隱藏的影像資訊同時嵌入，達到雙重加密。影像經由實際輸出後，可透過人眼、特殊解碼器（光柵）、電腦程式解密，達到防偽效果。本實驗所設計之雙重加密影像，兼具條碼隱藏資訊功能更顯示有意義的色彩影像。

The main purpose of this research is to design the double encrypted binary image by tilted halftone dots. The modified digital halftoning technique is applied to covert the continue image into binary image with titled halftone dots. Both the figurative watermark pattern and the hidden data according to the pseudo-random number are encoded in the binary image printed. The hidden image and data can detected the by human eyes, optical decoder and digital image processing. The double encrypted binary image not only has the bar code capability but also displays meaningful image.