多重光譜浮水印於二維條碼圖像防偽設計

Abstract

目前世界各國浮水印技術大多聚集於數位浮水印，應用於紙張載體為主的實體浮水印技術研究與應用則相對較少，當前實體浮水印研究多應用於紙張防偽、光學防偽、文件複印，且為單一各自獨立的圖像防偽浮水印技術。本研究目的為整合數位浮水印技術與實體浮水印技術製作多重光譜（可視光、紅外光及紫外光）浮水印圖像於QR Code之加值應用。圖像防偽設計乃結合二維條碼QR Code數位浮水印與實體浮水印之整合設計，將增加此研究領域之創新加值應用性。本研究目的在於建立一個多重的防偽設計，結合不同光學特性成為綜效防偽，以提高安全文件偽造製作之困難度，隱藏多重光譜浮水印圖像於QR Code之中。研究方法採用數位半色調和印墨材料在紅外線、紫外線照射下的光學特性差異，構成具多重防偽功能的浮水印。在可視的光源中置入QR Code浮水印，於不可視的紅外線與紫外線光譜區藏入不同浮水印，並針對不同網點面積百分比之網點進行資訊隱藏，將顯微結構分散後之調幅網點與調頻網點在相同濃度匹配下達到多光譜浮水印隱藏，作為本研究多重光譜浮水印圖像防偽設計之參考依據，以找到最佳隱藏的濃度組合。文件複印後QR Code因浮水印圖像干擾而失去作用，透過紅外線與紫外光檢驗隱藏浮水印，得知文件是否經過偽造。圖像藉由在不同「光譜」的區段使得人眼和檢驗設備（攝影機紅外光與紫外光）看到不同的影像，ㄧ般民眾可以透過手持裝置讀取二維條碼QR Code，獲取安全文件檢查碼，驗證文件，並透過分光儀設備，在不同光譜區段下驗証文件真偽。 實驗成果顯示QR Code圖像濃度控制在濃度50%以下，IR浮水印濃度控制在10~20%，UV浮水印濃度控制70%，則多重光譜浮水印可以達到資訊隱藏，並且透過攝影機與紫外燈檢驗設備看到隱藏在二維條碼中的不同浮水印。半色調QR Code也能夠同時被手機讀取連結產品訊息。因此進一步將此多重光譜浮水印防偽設計研究整合於安全文件，不但可達到技術的創新加值，也擴展QR Code技術本身的價值。多重光譜圖像浮水印防偽設計其應用不僅可以宣告版權，更能嚇阻非授權複製或偽造。Nowaday, the studies and applications on printed watermark is relatively fewer due to the research and development of digital watermark is the majority. Most of the applications of printed watermark are used in anti-counterfeiting papers, optical anti-counterfeiting technologies, and document authentication. They are always individual and independent image watermarks. In this reaserch, we attempt to integrate both digital and printed watermark technologies into “Multiple Spectrum Watermark in the 2D Bar Code”. By digital half-toning methods and the optical characteristics of ink material, multiple anti-counterfeiting watermarks can be generated. Under the visible light, QR Code was embedded and the watermark was implanted under the invisible light like infrared and UV light. Meanawhile, the information can be hidden from the printed halftone dots in full spectra by using the amplitude modulation (AM) and frequency modulation (FM) at microscopic level. The optimal combination can be applied to the design of anti-counterfeiting. For example, QR Code would not be identified after replication due to the interference of watermark. By the inspection of infrared or UV light, it is able to verify if the document is false or not. People can easily acquire QR Code information from the documents by using smart phone, in the documents can show different images by using the spectroscopic instrument. . The experimental results show when the density of QR Code is controlled below 50%, the concentration of IR watermark is controlled around 10 to 20 percents, and the concentration of UV watermark are higher than 70%, the information can be hidden by the multi-spectrum watermark and different watermark hidden in 2D Bar Code are observed by using camera and inspection instrument. The QR Code invisible light is still readable using smart phone. The multi-spectrum watermark thus can be integrated into the design of anti-counterfeiting technology for the documentary security. Furthermore, the application of QR Code can extend the information from printed media to virtual space.