Conversion principle based on color space in special color printing
What is Al technical title?
Al technical title is built by PatSnap Al team. It summarizes the technical point description of the patent document.
A technology for printing images and digital watermarking, which is applied in image watermarking, image data processing, image data processing, etc., and can solve the problems of detection security, robustness against printing, and increased printing costs, etc.
Active Publication Date: 2018-08-28
DALIAN POLYTECHNIC UNIVERSITY
View PDF8 Cites 12 Cited by
Summary
Abstract
Description
Claims
Application Information
AI Technical Summary
This helps you quickly interpret patents by identifying the three key elements:
Problems solved by technology
Method used
Benefits of technology
Problems solved by technology
[0004] In 2003, Alattar, O. and Reed, A. et al. proposed the spot color digital watermarking algorithm for the first time. First, calculate the spot color brightness mapping factor and yellow saturation to modulate the watermark signal, and then embed it into the spot color channel. At the same time, pass the intensity The factor dynamically adjusts each pixel, and the algorithm is effective for most spot colors, but not for some spot colors, such as: silvery yellow, silvery gold, silver and gold, etc.; 2015, Reed A. and Filler T. et al. proposed a spot color watermarking algorithm in packaging printing. This algorithm uses CMY three-color overprinting for a certain proportion of spot colors, and embeds watermark information in the CMY three-color channel, such as PANTONE 221 spot color, which can be decomposed into 75% The spot color channel and 25% of the CMY channel are superimposed, and the watermark is embedded in the 25% of the CMY channel, but the use of CMY to simulate the spot color will produce a certain color difference, and three additional printing plates of C, M and Y are added, which increases the printing cost. cost
However, the SVD watermarking algorithm also has defects. Based on the SVD watermarking algorithm, only the singular value eigenvector S of the carrier image is used when embedding the watermark information. Because the singular value S of the image only represents the brightness information of the image, and the two U and V The orthogonal matrix reflects the texture and geometric structure characteristics of the image. If U and V are used to synthesize the S vector of the image without watermark when extracting the watermark, an image similar to the original watermark image structure can also be reconstructed. resulting in detection security issues
For this problem, the solution based on the digital signature mechanism is relatively mature, but the robustness against printing needs to be improved
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more
Image
Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
Click on the blue label to locate the original text in one second.
Reading with bidirectional positioning of images and text.
Smart Image
Examples
Experimental program
Comparison scheme
Effect test
Embodiment 1
[0111] Such as figure 2 As shown, the spot color printing image digital watermarking method, the specific steps are as follows:
[0112] (1) Watermark preprocessing
[0113] In order to improve the security of the watermark, Arnold scramble encryption is performed on the watermark image to generate scrambled encrypted watermark image information; the watermark image after scrambling is a garbled image with no regular shape, no obvious texture features, and no rules; through To scramble the watermark, the distribution points of the error bits can be redistributed by moving the spatial pixels. Therefore, the scrambling and encryption processing of the watermark image can enhance the security and robustness of the watermark.
[0114] (2) spot color separation
[0115] For the color image, use the Neuschberg mathematical model to calculate the amount of spot color ink, and obtain the spot color separation map. The L*, a* and b* of the spot color image are known, and the tristi...
Embodiment 2
[0192] In order to verify the effectiveness of the present invention, the inventor has carried out a series of experiments; by fully consulting the literature, there are few watermarking algorithms for spot color printing images in recent years, only the literature Reed A, Filler T, Falkenstern K, et al.Watermarking spot colors in packaging[C] / / SPIE / IS&T Electronic Imaging. International Society for Optics and Photonics, Bellingham, WA, US, 2015, (9409): 061-0613. (hereinafter referred to as "existing technology"), in previous research Based on this, a spot color image printing watermarking algorithm is proposed, so a comprehensive comparison is made between the experiment and the spot color printing image watermarking algorithm proposed in the prior art, mainly including watermark transparency evaluation, digital signature extraction test and resistance to printing-scanning Process robustness testing.
[0193] 1. Experimental environment and parameter settings
[0194] In th...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more
PUM
Login to view more
Abstract
The invention provides a conversion principle based on color space in special color printing, and a special color printing image digital watermark method and system combining IWT and SVD. According tothe method and the system, a carrier image is decomposed into a special color channel, and the special color channel is subjected to IMWT conversion, then the watermark information is directly embedded into the singular value of each sub-band of the first-stage IWT. In order to improve watermark safety, Arnold scrambling encryption processing is conducted on the watermark image, and digital signature capable of resisting the printing-scanning process is embedded in the U and V of the image. In order to improve the robustness of digital signature and watermark, a step correction model for scanning a special color image is provided, and the scanned images are corrected, the digital signatures are extracted for verification, and the watermark information can be extracted if the digital signature is verified. The method has excellent performances in terms of watermark transparency, robustness and capacity, and can resist the printing-scanning process of the offset plate. The algorithm complexity is low, the execution efficiency is high, and the extraction time is not less than 1 second.
Description
technical field [0001] The invention belongs to the technical field of digital watermarking of printed images, and in particular relates to a method and system for digital watermarking of spot-color printed images. Background technique [0002] There are two ways of color reproduction of printed images: the first is subtractive color reproduction, which uses cyan (C), magenta (M), yellow (Y) and black (K) inks to overprint to achieve color image reproduction; the second The first is spot color printing reproduction, which refers to the method of using other inks other than CMYK four-color ink to reproduce the color of the original. Such as figure 1 As shown, when the spot color PANTONE168C uses four-color printing, it can be decomposed into four channels of C, M, Y, and K, while it is only decomposed into one spot color channel when using spot color printing. Therefore, there are fewer channels for spot color printing images to embed watermark information, and the requirem...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more
Application Information
Patent Timeline
Application Date:The date an application was filed.
Publication Date:The date a patent or application was officially published.
First Publication Date:The earliest publication date of a patent with the same application number.
Issue Date:Publication date of the patent grant document.
PCT Entry Date:The Entry date of PCT National Phase.
Estimated Expiry Date:The statutory expiry date of a patent right according to the Patent Law, and it is the longest term of protection that the patent right can achieve without the termination of the patent right due to other reasons(Term extension factor has been taken into account ).
Invalid Date:Actual expiry date is based on effective date or publication date of legal transaction data of invalid patent.
Login to view more 
Login to view more