TWI497443B - 浮水印圖像及其製造方法 - Google Patents

浮水印圖像及其製造方法 Download PDF

Info

Publication number
TWI497443B
TWI497443B TW102120135A TW102120135A TWI497443B TW I497443 B TWI497443 B TW I497443B TW 102120135 A TW102120135 A TW 102120135A TW 102120135 A TW102120135 A TW 102120135A TW I497443 B TWI497443 B TW I497443B
Authority
TW
Taiwan
Prior art keywords
amplitude modulation
dots
dot
region
image
Prior art date
Application number
TW102120135A
Other languages
English (en)
Other versions
TW201447806A (zh
Inventor
Hsi Chun Wang
Ya Wen Cheng
Original Assignee
Univ Nat Taiwan Normal
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Univ Nat Taiwan Normal filed Critical Univ Nat Taiwan Normal
Priority to TW102120135A priority Critical patent/TWI497443B/zh
Priority to US14/082,897 priority patent/US9124819B2/en
Publication of TW201447806A publication Critical patent/TW201447806A/zh
Application granted granted Critical
Publication of TWI497443B publication Critical patent/TWI497443B/zh

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32149Methods relating to embedding, encoding, decoding, detection or retrieval operations
    • H04N1/32154Transform domain methods
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32149Methods relating to embedding, encoding, decoding, detection or retrieval operations
    • H04N1/32203Spatial or amplitude domain methods
    • H04N1/32256Spatial or amplitude domain methods in halftone data
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T1/00General purpose image data processing
    • G06T1/0021Image watermarking
    • G06T1/0028Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32149Methods relating to embedding, encoding, decoding, detection or retrieval operations
    • H04N1/32203Spatial or amplitude domain methods
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32149Methods relating to embedding, encoding, decoding, detection or retrieval operations
    • H04N1/32203Spatial or amplitude domain methods
    • H04N1/32208Spatial or amplitude domain methods involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32149Methods relating to embedding, encoding, decoding, detection or retrieval operations
    • H04N1/32203Spatial or amplitude domain methods
    • H04N1/32219Spatial or amplitude domain methods involving changing the position of selected pixels, e.g. word shifting, or involving modulating the size of image components, e.g. of characters
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32149Methods relating to embedding, encoding, decoding, detection or retrieval operations
    • H04N1/32288Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
    • H04N1/32299Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image using more than one embedding method
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T1/00General purpose image data processing
    • G06T1/0021Image watermarking
    • G06T1/005Robust watermarking, e.g. average attack or collusion attack resistant
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00General purpose image data processing
    • G06T2201/005Image watermarking
    • G06T2201/0051Embedding of the watermark in the spatial domain
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00General purpose image data processing
    • G06T2201/005Image watermarking
    • G06T2201/0052Embedding of the watermark in the frequency domain
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00General purpose image data processing
    • G06T2201/005Image watermarking
    • G06T2201/0061Embedding of the watermark in each block of the image, e.g. segmented watermarking
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00General purpose image data processing
    • G06T2201/005Image watermarking
    • G06T2201/0202Image watermarking whereby the quality of watermarked images is measured; Measuring quality or performance of watermarking methods; Balancing between quality and robustness
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00838Preventing unauthorised reproduction
    • H04N1/00883Auto-copy-preventive originals, i.e. originals that are designed not to allow faithful reproduction
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4051Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4051Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size
    • H04N1/4052Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size by error diffusion, i.e. transferring the binarising error to neighbouring dot decisions
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4051Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size
    • H04N1/4052Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size by error diffusion, i.e. transferring the binarising error to neighbouring dot decisions
    • H04N1/4053Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a dispersed dots halftone pattern, the dots having substantially the same size by error diffusion, i.e. transferring the binarising error to neighbouring dot decisions with threshold modulated relative to input image data or vice versa
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4055Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4055Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
    • H04N1/4056Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern the pattern varying in one dimension only, e.g. dash length, pulse width modulation [PWM]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4055Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
    • H04N1/4057Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern the pattern being a mixture of differently sized sub-patterns, e.g. spots having only a few different diameters
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40Picture signal circuits
    • H04N1/405Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
    • H04N1/4055Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
    • H04N1/4058Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern with details for producing a halftone screen at an oblique angle
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/32Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N2201/3201Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N2201/3225Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title of data relating to an image, a page or a document
    • H04N2201/3233Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title of data relating to an image, a page or a document of authentication information, e.g. digital signature, watermark

Description

浮水印圖像及其製造方法
本發明係關於一種浮水印圖像及其製造方法,特別是關於一種由調幅網點及調頻網點所組成之浮水印圖像及其製造方法。
隨著科技不斷進步,印表機、掃描機等複製設備已可精準複製文件,進而使偽造者利用上述複製設備偽造出高品質的複製品。近年來,文件與書籍受到非法複製之事件時有所聞,使版權保護、品牌保護等相關議題逐漸受到重視,許多應用於實體文件上的防偽技術也不斷應運而生,例如:紙張浮水印、凹版印刷、紅外線油墨、微小字、窗式安全線等,然而,上述防偽技術不僅需要特殊設備,更需耗費高額成本,對於保護一般出版書籍或公司機密文件有所限制。
在眾多防偽技術中,混合網點數位浮水印技術不須使用特殊設備即可達到紙張的防偽功能,該浮水印技術是利用調幅網點(Amplitude Modulation,AM)及調頻網點(Frequency Modulation,FM)的浮水印進行遮罩合成,藉由濃度匹配導表找出較佳的匹配參數,以進行調幅網點及調頻網點的濃度校正,並且將該浮水印輸出於文件上,使該文件再經過複印或掃描,該浮水印就會浮現而達到防偽的功能。
請參閱第1、2圖所示,為混合網點的一浮水印1,該浮水印1包含多個調幅網點11及多個調頻網點12,由於該等調幅網點11及該等調頻網點12的噴墨結構有所差異,使該等 調幅網點11及該等調頻網點12產生不同的網點擴張情形,進而影響該浮水印1的隱藏效果,為確保該浮水印1隱藏品質,在混合該等調幅網點11及該等調頻網點12時,需另外再透過濃度匹配導表,對該等調幅網點11及該等調頻網點12進行濃度校正,另外,由於該等調幅網點11及該等調頻網點12的網點擴張率不一致,使網點的濃度表現在製程中不穩定,該浮水印1的隱藏品質較不易獲得控制。
本發明之主要目的在於提供一種浮水印圖像的製造方法,其係利用在每一該調幅網點填入數個空白部,可分散該等調幅網點的著墨濃度,進而拉近該等調幅網點及調頻網點的網點擴張率。
本發明之次要目的在於提供一種浮水印圖像的製造方法,其係利用在每一該調幅網點填入數個空白部,可分散該等調幅網點的著墨濃度,藉此免除該等調幅網點及調頻網點的濃度校正。
為達上述之目的,本發明提供一種浮水印圖像的製造方法,其包含以下步驟:利用數個調幅網點組成一個人化圖像的一第一區域,其中每一該調幅網點具有數個墨點部及數個空白部,每一該調幅網點之空白部位於同一該調幅網點的二相鄰墨點部之間;利用數個調頻網點組成該個人化圖像的一第二區域;及根據一數位半色調過網技術將該個人化圖像印刷輸出至一原稿文件之表面,以形成一具有在複印後可顯現其原隱藏之浮水印圖像。
為達上述之目的,本發明提供一種浮水印圖像,其印刷形成在一文件表面上,該浮水印圖像包含一第一區域及一第二區域,該第一區域由數個調幅網點組成,其中每一該調幅網點具有數個墨點部及數個空白部,每一該調幅網點之空白 部位於同一該調幅網點的二相鄰墨點部之間,該第二區域由數個調頻網點組成。
在本發明之一實施例中,該第一區域為該個人化圖像的至少一圖像區域,該第二區域為該個人化圖像的至少一背景區域。
在本發明之一實施例中,該第一區域的著墨濃度值為2%至8%。
在本發明之一實施例中,該第二區域的著墨濃度值為2%至8%。
在本發明之一實施例中,該第一區域的著墨濃度值與該第二區域的著墨濃度值相同。
在本發明之一實施例中,在每一該調幅網點中,每二相鄰該墨點部之間的間隔距離相同。
如上所述,利用在每一該調幅網點填入數個空白部,可分散該等調幅網點的著墨濃度,進而拉近該等調幅網點及調頻網點的網點擴張率,藉此免除該等調幅網點及調頻網點的濃度校正。
1‧‧‧浮水印
11‧‧‧調幅網點(AM)
12‧‧‧調頻網點(FM)
21‧‧‧調幅網點(AM)
211‧‧‧墨點部
212‧‧‧空白部
22‧‧‧調頻網點(FM)
3‧‧‧個人化圖像
31‧‧‧第一區域
32‧‧‧第二區域
41‧‧‧中心區塊
42‧‧‧外部區塊
P‧‧‧原稿
P’‧‧‧複印稿
G‧‧‧AM網點
G’‧‧‧FM網點
W‧‧‧遮罩
~W‧‧‧背景區域
M‧‧‧最後影像
第1圖:現有混合網點的一浮水印的示意圖。
第2圖:第1圖的調幅網點及調頻網點的微結構的示意圖。
第3圖:本發明一實施例之浮水印圖像的示意圖。
第4圖:第3圖的調幅網點及調頻網點的微結構的示意圖。
第5圖:本發明一實施例之浮水印圖像進行數位半色調過網流程的示意圖。
第6、7圖:本發明一實施例之浮水印圖像實施在濃度匹配導表的示意圖。
第8、9圖:現有混合網點的一浮水印分別實施在兩種不 同紙張材質的濃度匹配導表的示意圖。
第10、11圖:本發明一實施例之浮水印圖像分別實施在兩種不同紙張材質的濃度匹配導表的示意圖。
第12、13圖:本發明一實施例之使用狀態的防複印紙之原稿及複印稿的示意圖。
為了讓本發明之上述及其他目的、特徵、優點能更明顯易懂,下文將特舉本發明較佳實施例,並配合所附圖式,作詳細說明如下。再者,本發明所提到的方向用語,例如上、下、頂、底、前、後、左、右、內、外、側面、周圍、中央、水平、橫向、垂直、縱向、軸向、徑向、最上層或最下層等,僅是參考附加圖式的方向。因此,使用的方向用語是用以說明及理解本發明,而非用以限制本發明。
本發明係提供一種浮水印圖像及其製造方法,其主要係藉由使用調幅(AM)網點及調頻(FM)網點之混合網點數位浮水印技術來設計個人化圖像於一原稿文件上,並將該個人化圖像列印輸出至該原稿文件上成為浮水印圖像,其中該原稿文件能在複印後造成複印件之原隱藏浮水印圖像內容可顯現,故可藉此顯示版權保護,以有效嚇阻非授權複製。
請參照第3及4圖所示,本發明一實施例中,該浮水印圖像的製造方法主要包含下列步驟:利用數個調幅網點21組成一個人化圖像3的一第一區域31,其中每一該調幅網點21具有數個墨點部211及數個空白部212,每一該調幅網點21之空白部212位於同一該調幅網點21的二相鄰墨點部211之間(如第4圖所示);利用數個調頻網點22組成該個人化圖像3的一第二區域32;及根據一數位半色調過網技術將該個人化圖像3印刷輸出至一原稿文件之表面(如第12圖所示),以形成一具有在複印後顯現(如第13圖所示)原隱藏浮水印圖像。本發明將 於下文逐一詳細說明上述各步驟的實施細節及其原理。
本發明實施例之浮水印圖像的製造方法,首先提供一個人化圖像3。該個人化圖像3(原稿)包含一第一區域31及一第二區域32,在本實施例中,該第一區域31為該等調幅網點21組成的至少一圖像區域,該第二區域32為該等調頻網點22組成的至少一背景區域,其中該第一區域31的著墨濃度值與該第二區域32的著墨濃度值相同,例如該第一區域31的著墨濃度值為2%至8%,該第二區域32的著墨濃度值為2%至8%。
本發明在進行過網時,原稿之個人化圖像3可分為兩個部份:(1)以該等調幅網點21設計的第一區域31與(2)以該等調頻網點22設計之第二區域32,其中該第一區域31及第二區域32最後整合於一原稿文件上,以下將對於該等調幅網點21、該等調頻網點22及數位半色調過網方法等進行說明:該數位半色調過網(digital halftoning)方法可以區分為點陣調色法(ordered dithering)及誤差擴散法(error diffusion)。其中,點陣調色法(ordered dithering)主要用以形成該等調幅網點21,而誤差擴散法(error diffusion)主要用以形成該等調頻網點22。
點陣調色法之演算原理在於比對連續調原稿與臨界值矩陣(threshold matrix),以決定個別像素點生成為1或0的訊號值,先把影像分割成與臨界值矩陣相同大小的許多區塊,因臨界值矩陣內所設計數值排列之不同,可以產生不同的網點結構影像,對於數位印刷設備來說,點陣調色法就是指引數位印刷設備如何著墨的方式。更具體來說,就是對區塊影像進行半色調處理,其臨界值的產生就是先將原灰階影像g(i,j),透過公式(1)將原灰階值量化成臨界值矩陣的階調數g’(i,j),其中N1 與N2 代表臨界值矩陣的長和寬。
得到臨界值矩陣的階調數g’(i,j)後,再透過公式(2)與臨界值矩陣t(m,n)作比對以決定像素點成為1或0的訊號值:
舉例而言,若在一區塊之階調數為29,且在此區域之子區塊大小為8×8的像素(pixel),數位印刷輸出設備會依照臨界值的數值來著墨,其結果為在64個子位置中,有29個位置被填上黑墨。而本發明在該等調幅網點21的基礎上,針對每一該調幅網點21再填入該等空白部212,使該等墨點部211皆為單獨排列,而且在每一該調幅網點21中,每二相鄰該墨點部211之間的間隔距離相同。
另一方面,誤差擴散法(Error Diffusion)是由Robert Floyd和Louis Steinberg提出,影像在兩階化的過程中所造成的誤差,由最左上角的像素之誤差開始擴散至鄰近但尚未二階化的像素點上,其他吸收誤差且尚未二階化的像素點再繼續執行兩階化及誤差擴散,直到最後一個像素點為止,其演算法可以透過方程式(3)來表示,其中X為原始像素點的灰階值,在與臨界值T比較後,產生最後的兩階值b。而誤差擴散遮罩如方程式(4)所示。
請參照第5圖所示,本發明實施例之浮水印圖像之製造方法接著係:根據該數位半色調過網的技術,將該個人化圖像3印刷輸出至一原稿文件之表面,以形成一可在複印後顯現原隱藏浮水印圖像。在本步驟中,經由第5圖的流程圖進行數位半色調過網,可將浮水印圖像3輸出到一原稿文件之中,其中該原稿文件例如為筆記本、書籍、身份證件、證書或具有安全加密需求之其他文件等。再者,第5圖的流程圖之方程式如方程式(5)所示:M=(G∩W)∪(G’∩~W)............(5)
其中W為遮罩X,G為AM網點,~W為遮罩X之背景區域,G’為FM網點,M為最後影像,∩表示交集,∪表示聯集。
藉由上述浮水印圖像之製造方法,可以製作完成一種浮水印圖像3,其印刷形成在一原稿文件(即印刷品)的表面上,如第3及4圖所示,該浮水印圖像3包含一第一區域31及一第二區域32,該第一區域31由數個調幅網點21等間距排列組成,該第二區域32由數個調頻網點22不等間距排列組成,其中每一該調幅網點21具有數個墨點部211及數個空白部212,每一該調幅網點21之空白部212位於同一該調幅網點21的二相鄰墨點部211之間,且該第一區域31的著墨濃度值與該第二區域32的著墨濃度值相同。同一該調幅網點21的二相鄰墨點部211之間的空白部212之間距(尺寸)明顯小於各二相鄰調幅網點21之間的間距(尺寸),例如該空白部212之間距與各二相鄰調幅網點21之間的間距具有1:10至1:20之比例,但並不限於此。
請參閱第6、7圖所示,第6圖為方格形狀的濃度匹配導表的示意圖,中心區塊41採用8X8或其他尺寸臨界值矩陣形成調幅網點(AM),而外部區塊42以調頻網點(FM)進行半 色調過網,第7圖為組合2%至8%的濃度匹配導表的示意圖,其中將調幅網點及調頻網點的著墨濃度值同樣設定為2%至8%,藉此檢視調幅網點及調頻網點兩種網點輸出後之著墨濃度的匹配情形。
請參閱第8、9圖所示,為傳統式混合網點分別印刷於兩種不同紙張材質上的濃度匹配導表的示意圖,由於網片在晒版及印刷輸出的製程中產生網點遺失及不同程度的網點擴張,使調頻網點濃度數值需高於調幅網點才能達到濃度平衡,因此產生期望值(虛線箭頭)與實際值(實線箭頭)之間的落差,比較第8、9圖可知,列印在第二種紙張材質上的實際值(實線箭頭)比列印在第一種紙張材質上所產生的偏移更為嚴重。由此可知,利用傳統式混合網點所製作之浮水印,在不同印刷條件下(不同紙張材質),浮水印的隱藏效果並不穩定。
請參閱第10、11圖所示,為本發明浮水印圖像之製造方法分別印刷於兩種不同紙張材質上的濃度匹配導表的示意圖,其中所產生的期望值(虛線箭頭)與實際值(實線箭頭)趨於一致,即相同濃度數值之調幅網點及調頻網點皆可相互匹配達到濃度平衡效果,進而可平衡調幅網點及調頻網點的網點擴張率,另外,如第12、13圖所示,分別為防複印紙之原稿P及複印稿P’的示意圖,該原稿P由本發明浮水印圖像之製造方法製造而成,再經過影印機複印而產生該複印稿P’,該複印稿P’會產生該浮水印圖像3,藉此達到嚇阻非授權複製的效果。
如上所述,利用在每一該調幅網點21填入數個空白部212,可分散該等調幅網點21的著墨濃度,進而拉近該等調幅網點21及調頻網點22的網點擴張率,藉此免除該等調幅網點21及調頻網點22的濃度校正。另外,本發明浮水印圖像之製造方法在不同的材質上印刷,可將該等調幅網點21及調頻網點22的網點擴張率維持相同,並克服網點耗損或擴張程度不 一致的問題,使浮水印的隱藏品質也能獲得控制。
雖然本發明已以較佳實施例揭露,然其並非用以限制本發明,任何熟習此項技藝之人士,在不脫離本發明之精神和範圍內,當可作各種更動與修飾,因此本發明之保護範圍當視後附之申請專利範圍所界定者為準。
21‧‧‧調幅網點(AM)
211‧‧‧墨點部
212‧‧‧空白部
22‧‧‧調頻網點(FM)

Claims (11)

  1. 一種浮水印圖像的製造方法,其包含步驟:利用數個調幅網點組成一個人化圖像的一第一區域,其中每一該調幅網點具有數個墨點部及數個空白部,每一該調幅網點之空白部位於同一該調幅網點的二相鄰墨點部之間,且同一該調幅網點內的二相鄰墨點部之間的空白部之間距明顯小於各二相鄰調幅網點之間的間距;利用數個調頻網點組成該個人化圖像的一第二區域;及根據一數位半色調過網技術將該個人化圖像印刷輸出至一原稿文件之表面,以形成一具有在複印後顯現原隱藏浮水印圖像。
  2. 如申請專利範圍第1項所述之浮水印圖像的製造方法,其中該第一區域為該個人化圖像的至少一圖像區域,該第二區域為該個人化圖像的至少一背景區域。
  3. 如申請專利範圍第1項所述之浮水印圖像的製造方法,其中該第一區域的著墨濃度值為2%至8%。
  4. 如申請專利範圍第1項所述之浮水印圖像的製造方法,其中該第二區域的著墨濃度值為2%至8%。
  5. 如申請專利範圍第1項所述之浮水印圖像的製造方法,其中該第一區域的著墨濃度值與該第二區域的著墨濃度值相同。
  6. 如申請專利範圍第1項所述之浮水印圖像的製造方法,其中在每一該調幅網點中,每二相鄰該墨點部之間的間隔距離相同。
  7. 一種浮水印圖像,其印刷形成在一文件表面上,該浮水印圖像包含:一第一區域,由數個調幅網點組成,其中每一該調幅網點具有數個墨點部及數個空白部,每一該調幅網點之空白部位於同一該調幅網點的二相鄰墨點部之間,且同一該調幅網點內的二相鄰墨點部之間的空白部之間距明顯小於各二相鄰調幅網點之間的間距;一第二區域,由數個調頻網點組成一個人化圖像的第二區域,該第一區域及第二區域構成該個人化圖像。
  8. 如申請專利範圍第7項所述之浮水印圖像,其中該第一區域的著墨濃度值為2%至8%。
  9. 如申請專利範圍第7項所述之浮水印圖像,其中該第二區域的著墨濃度值為2%至8%。
  10. 如申請專利範圍第7項所述之浮水印圖像,其中該第一區域的著墨濃度值與該第二區域的著墨濃度值相同。
  11. 如申請專利範圍第7項所述之浮水印圖像,其中在每一該調幅網點中,每二相鄰該墨點部之間的間隔距離相同。
TW102120135A 2013-06-06 2013-06-06 浮水印圖像及其製造方法 TWI497443B (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
TW102120135A TWI497443B (zh) 2013-06-06 2013-06-06 浮水印圖像及其製造方法
US14/082,897 US9124819B2 (en) 2013-06-06 2013-11-18 Watermark and manufacturing method therefor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
TW102120135A TWI497443B (zh) 2013-06-06 2013-06-06 浮水印圖像及其製造方法

Publications (2)

Publication Number Publication Date
TW201447806A TW201447806A (zh) 2014-12-16
TWI497443B true TWI497443B (zh) 2015-08-21

Family

ID=52005252

Family Applications (1)

Application Number Title Priority Date Filing Date
TW102120135A TWI497443B (zh) 2013-06-06 2013-06-06 浮水印圖像及其製造方法

Country Status (2)

Country Link
US (1) US9124819B2 (zh)
TW (1) TWI497443B (zh)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI611372B (zh) * 2016-03-02 2018-01-11 China Engraving&Printing Works 以影像分區佈置異質防僞網點和虛擬灰色平衡之方法
US10027847B2 (en) * 2016-09-22 2018-07-17 Kyocera Document Solutions Inc. Selection of halftoning technique
CN111988488B (zh) * 2020-09-03 2021-12-17 北大方正集团有限公司 网点生成方法、装置、电子设备及存储介质

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001071960A1 (en) * 2000-03-18 2001-09-27 Digimarc Corporation Transmarking, watermark embedding functions as rendering commands, and feature-based watermarking of multimedia signals
US20090031134A1 (en) * 2001-12-13 2009-01-29 Levy Kenneth L Digital watermarking with variable orientation and protocols
TW201015444A (en) * 2008-10-06 2010-04-16 Univ Nat Taiwan Normal Manufacturing method of printed article having hidden bar code
TW201322174A (zh) * 2011-11-22 2013-06-01 Univ Nat Taiwan Normal 文件複印後呈現內容意義改變之浮水印製作方法

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4924301A (en) * 1988-11-08 1990-05-08 Seecolor Corporation Apparatus and methods for digital halftoning
US5171040A (en) * 1991-03-29 1992-12-15 Invisible Images, Inc. Copy-invalidating document
US6000728A (en) * 1991-07-12 1999-12-14 The Standard Register Company Security document
US5953988A (en) * 1995-09-12 1999-09-21 Agfa Gevaert, N.V. Screen printing process using rotated screens
US5954368A (en) * 1996-11-19 1999-09-21 The Standard Register Company Security document containing a non-orthogonal array
US5790703A (en) * 1997-01-21 1998-08-04 Xerox Corporation Digital watermarking using conjugate halftone screens
US6118935A (en) * 1997-04-01 2000-09-12 Professional Software Technologies, Inc. Digital halftoning combining multiple screens within a single image
US5892588A (en) * 1997-10-02 1999-04-06 Professional Software Technologies Inc. Digital halftoning combining dot size modulation screen with dot frequency modulation screen within a single image
JP4324278B2 (ja) * 1999-05-21 2009-09-02 富士フイルム株式会社 網点による階調再現方法、網目版出力装置、および網目版
US7307761B2 (en) * 2002-12-12 2007-12-11 Electronics For Imaging, Inc. Methods and apparatus for watermarking digitally printed documents
US7359091B2 (en) * 2003-01-15 2008-04-15 Xerox Corporation Multi-bit output sampled threshold array halftoner
US7126724B2 (en) * 2003-03-11 2006-10-24 Kodak Graphic Communications Canada Company Flexographic printing
US8363282B2 (en) * 2003-10-31 2013-01-29 Hewlett-Packard Development Company, L.P. Halftone screening and bitmap based encoding of information in images
US20060284411A1 (en) * 2004-12-16 2006-12-21 Wu Judy W Digitally printed anti-copy document and processes and products therefor
TWI298231B (zh) * 2005-01-28 2008-06-21 Univ Nat Taiwan Normal

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001071960A1 (en) * 2000-03-18 2001-09-27 Digimarc Corporation Transmarking, watermark embedding functions as rendering commands, and feature-based watermarking of multimedia signals
US20090031134A1 (en) * 2001-12-13 2009-01-29 Levy Kenneth L Digital watermarking with variable orientation and protocols
TW201015444A (en) * 2008-10-06 2010-04-16 Univ Nat Taiwan Normal Manufacturing method of printed article having hidden bar code
TW201322174A (zh) * 2011-11-22 2013-06-01 Univ Nat Taiwan Normal 文件複印後呈現內容意義改變之浮水印製作方法

Also Published As

Publication number Publication date
US20140362414A1 (en) 2014-12-11
TW201447806A (zh) 2014-12-16
US9124819B2 (en) 2015-09-01

Similar Documents

Publication Publication Date Title
JP5285642B2 (ja) 高解像度のスケール変更可能なグロス効果
US7580155B2 (en) Tools to embed information into digital visual works
JP6394975B2 (ja) 偽造防止用印刷物
US8355179B2 (en) Multi-tonal copy evident document methods and products
EP2015940B1 (en) Security enhanced print media with copy protection
TWI497443B (zh) 浮水印圖像及其製造方法
US8164799B2 (en) Digitally printed color anti-copy document in any resolution and processes and products therefor
JP4441634B2 (ja) 偽造防止用印刷物
TWI494896B (zh) 防偽浮水印圖像及其製造方法
CN107589921B (zh) 一种防复印底纹的生成方法和装置
JP6909471B2 (ja) 偽造防止印刷物用データの作成方法、偽造防止印刷物用データの作成用ソフトウェア及び偽造防止印刷物の発給システム
JP6991514B2 (ja) 偽造防止印刷物及び偽造防止印刷物用データの作成方法
TWI457852B (zh) 文件複印後呈現內容意義改變之浮水印製作方法
US20190109961A1 (en) Full color, digitally printed copy evident documents
JP6876221B2 (ja) 偽造防止印刷物
JP2003244428A (ja) スキャンしたイメージを識別する方法
JP6756953B2 (ja) 偽造防止印刷物用データの作成方法及びその作成用ソフトウェア
JP5215654B2 (ja) 偽造防止印刷物
TW201325935A (zh) 調變網點結構組合、應用該組合製作具有隱藏圖文印刷品的影像檔的方法及由其所製得的印刷品
TW201725130A (zh) 隱藏式圖文及其製造方法
JP6920719B2 (ja) 電子透かし装置および方法
JP4811588B2 (ja) 画像形成装置および印刷物
JP5190621B2 (ja) 秘匿情報を有する偽造防止印刷物
JP2021102284A (ja) 偽造防止帳票
WO2005006641A1 (en) Applying image watermarks to previously halftoned images