以綠雜訊半色調資訊隱藏技術結合圖像化二維條碼之多重防偽設計

Abstract

隨著電腦與網路科技的快速發展，各類圖文、影像資訊的處理、傳播及儲存，在電腦網路的環境下變得更為便捷且有效率，但電腦的虛擬世界及人們所處的現實世界仍須互相連結，才能更有效的傳達訊息，而二維條碼則能成為今日虛擬世界與現實世界連結的重要媒介，其中最常用的二維條碼類型為QR code (Quick Response Code)，搭配網際網路後更成為廣告文宣、網路購物以及下載連結等的重要角色。由於條碼外顯圖案設計是供機器所判讀，視覺上並不美觀，尤其在結合商品或證件等產品使用時，可能因產品尺寸或設計版面受限而影響整體外觀，因此有許多學者著手進行QR code圖像美化研究，但礙於條碼本身結構的限制，其美化效果仍有許多的發展空間。另一方面QR code 亦用於產品之防偽認證或網頁連結等，但有些不肖業者卻透過偽造與利用機會詐騙或非法取得個人資料的方式危害使用者安全，因此，條碼本身的安全防衛機制亦須加強。有鑑於此，故本研究使用誤差擴散之半色調技術結合資訊隱藏技術，透過半色調技術在影像數位過網的過程中將QR code資訊藏入，製成圖像化二維條碼。另以綠雜訊半色調技術產生種子網點，計算點之間的距離後進行區域劃分，再將各區域與原灰階影像比對後，佈入大小與間距皆不同的隨機網點，形成綠雜訊浮水印底紋，其網點隨機分佈的特性，結合圖像化二維條碼後，較不易產生干擾問題，並以四種不同解析度(dpi)之綠雜訊浮水印底紋進行結果測試，使圖像化二維條碼兼具視覺美觀及防偽驗證之效果，先以手機或複印設備偵測浮水印後，再透過手機條碼掃瞄判讀條碼內容，實現多重防偽設計的概念。經研究結果顯示，圖像化二維條碼除資訊隱藏效果較佳外，能以低成本達到美觀兼具多重防偽之功能，並在任何解析度之綠雜訊浮水印底紋的環境下皆可成功判讀。

關鍵字：圖像化二維條碼、綠雜訊、半色調、QR code、數位浮水印With the rapid development of computer and Internet technology, it is becoming increasingly more convenient and efficient to process, disseminate and store graphic and video information. Considering the fact that effective communication needs the linking of the virtual world with reality, two-dimensional barcodes are the most important and effective medium of connection between the virtual and the real worlds. As the barcode’s external design is made for ease of machine scanning, it is usually visually unremarkable or even ugly. When combined with merchandise, or important documents, barcodes may be constrained by size and design layout, and in turn affect the appearance of the entire product. Even with many scholars focusing their research on beautifying the QR code, its structural limitations still provide ample space for development in this regard. On another hand, QR codes are also used for authentication processes or links to web pages. However, there are cases of unscrupulous persons using these codes to defraud or illegally obtain personal data of others by forgery and taking advantage of the QR code’s versatile abilities. It is therefore important to increase the security of the QR code’s structure to decrease risk to users. This study will use Data Hiding Error Diffusion (DHED) technique to produce image-combined two-dimensional barcodes. Also, the study will create seed algorithm with a differently sized dotted watermark and shading by using the green noise halftone algorithm as a base. The feature of the randomized dotting means that after combining the graphic with the QR code, the potential for disturbances will be lowered. This will be tested using four different resolutions (dpi) of the green noise floating water shading. Then combine them with green noise halftone watermarks in order to achieve both visual appeal and enhance security. The hidden watermarks and information stored in the image-combined two-dimensional barcodes will then be able to be interpreted by use of a smartphone. The results indicate that not only are image-combined two-dimensional barcodes able to safely hide information, they are a cost-effective ways of functionally achieving both visual appeal and the ability to deter counterfeiting, and in any resolution of the green noise floating shade of the environment can be read successful.

Key words: image of QR code, 2D barcode, green noise, halftoning, QR code, digital watermark