以疊紋技術設計具防偽功能之解合影像

Abstract

隨著數位科技的進步，偽造現象日益猖獗，版權保護已成為重要之議題，故有許多研究者致力於聲音、影像、視訊等數位媒體素材之浮水印技術。但對於實體輸出之列印影像防偽科技，其相關研究則相對較少，但仍有其市場需求性。本研究旨在利用疊紋(Moiré)技術，設計能拆解並重新合併之解合影像(Reassembled Images)，所設計之影像在解密前及解密後具有不同的圖像意函，故可誤導偽造者判讀錯誤，提高其防偽功能；並可調整解合影像排列之疏密濃度，形成不同深淺之階調性結構，進而在一定距離下，形成肉眼可辨視之階調性圖文。本研究所設計之解合影像，將原始臺灣影像拆解成四種不同的動物影像，拆解後之動物影像稱作「解合影像」，並計算在2x2矩陣中不同疏密濃度之解合影像排列方式，形成不同深淺階調之解合影像陣列，進而組成具階調性之圖文，並可將解合影像以不同色彩呈現。研究結果發現，經實際輸出底片，並以微透鏡陣列置於輸出之底片上，可將解合影像正確地還原為臺灣影像輪廓。本研究所製作之解合影像陣列，因其影像圖案十分細微，以肉眼無法直接辨識影像訊息，但若透過放大鏡或高精密度儀器檢視，即可清楚看到所設計之四種動物解合影像，為第一層防偽功能設計；接著再透過微透鏡陣列板觀察，可將動物解合影像還原為臺灣影像，達到第二層防偽功能設計。此外，本研究設計之解合影像，一旦經過複印，其解合影像微結構即遭到破壞，即便再覆上微透鏡陣列亦無法辨識其原有意義之影像內容，即達到第三層防偽功能設計，故可彰顯本技術之多重防偽功能。而本研究之解合影像並可依不同疏密濃度排列形成具階調性之彩色圖文，可增加其多元用途及趣味性，並提高未來應用的範疇。本研究所提之方法印製流程快速、成本低，其設計兼具防偽功能、美觀性及趣味性，在包裝設計、安全文件底紋等都有許多潛在的應用。With the progress of digital technology, copyright has become a significant issue. Therefore, many researchers have dedicated their efforts to watermark techniques for audio, images, videos and other digital media. By contrast, the researches thatrelated to anti-counterfeiting of printed images are much less addressed. However, the anti-counterfeiting technique both in academic research and industrial applications are still important subjects.This research uses the Moiré technique to design an encrypted image which can be dismantled and combined. The designed images are both meaningful before and after decryption to misleadthecounterfeiters. This research also adjuststhe concentrationsof scrambled images to form the variedtones ofthegraphic, whichcan be identified by naked-eyesfrom a certain distance. This research designsthe original image “Taiwan” which can be broke down into four different animal images, referringtothe"Reassembled Images”. In order to construct thetone of the graphic, the different concentrations ofreassembledimageswithin a 2x2 matrix are calculated to form the variedconcentrations of reassembledimagearray, and it can be presented in different colors.Through placing the micro-lens array upon the output negatives, the encrypted images can be restored precisely. The patterns of the reassembledimagearray are too small to be identified by naked-eyes, however, the four kinds of animal reassembledimagescan be observedclearlythrough a magnifying glass, whichisthe first anti-counterfeiting designof this research. Observingthrough a micro-lens array, the reassembledimagesof animalcan be restoredto theimageof Taiwan, whichis the second security design. In addition, the micro-structureof reassembledimageswill be decomposedafter copying, therefore, the original content cannot be restored with the micro-lens array, whichis the third security design. The design has artistic, interesting and anti-counterfeiting features which have many potential applications like package design and security documents.