Method for determining whether printed encoding information is not falsified
Related are a method and system for embedding information into encoding information. The method comprises the steps of first embedding the information into an embeddable image or a virtual image using a frequency domain embedding method, and then overlaying the embeddable image or the virtual image into a printed file in need of a variable code or a fixed code using a spatial domain processing method. In this way, the information not perceived by human eyes may be embedded into the encoding information using frequency domain and spatial domain transformation, the counterfeiting difficulty is extremely large, the cost is high, and the anti-counterfeiting purpose is achieved; and furthermore, the printing cost is not increased, thereby being beneficial to wide promotion and application.
1. A method for determining whether printed encoding information is falsified, comprising:
performing a gray transformation on a Red-Green-Blue (RGB) image, a Cyan-Magenta-Yellow (CMY) image or a virtual image to obtain a gray image G after the gray transformation;
performing a frequency domain transformation on the gray image G after the gray transformation to obtain an amplitude;
embedding an information into the amplitude after the frequency domain transformation according to a rule;
performing a frequency domain inverse transformation to obtain a gray image G′ of the information embedded, and calculating a difference between the gray image G′ and the gray image G;
generating a two-dimensional code, the two-dimensional code being a black-white two-dimensional code or a color two-dimensional code, and converting the two-dimensional code into an image information B;
performing a spatial domain processing on the difference, embedding into the image information B that needs to be embedded actually to obtain an image information B′ of the information embedded, and outputting the image information B′ to a digital printer to print;
after the image information B′ is printed out, extracting the information embedded out from the printed information so as to determine whether surface information of the printed information is falsified.
2. The method according to claim 1 , wherein the step of embedding an information into the amplitude after the frequency domain transformation according to a rule specifically comprises two steps: (1) performing the frequency domain transformation on the image G after the gray transformation to obtain the amplitude; and (2) when the information embedded is m-bit W, and information W (i) at an ith bit is 0 or 1, i=1, 2, . . . , m, each bit of the information W (i) is embedded into the amplitude of the gray image G after the frequency domain transformation according to the following rule:
ampG (i)′=ampG (i)+X, when the W (i) is 1;
ampG (i)′=ampG (i)−X, when the W (i) is 0;
where X is a given positive real number and i is the ith bit of the information embedded;
alternatively,
ampG (i)′=ampG (i)*(1+a), when the W (i) is 1;
ampG (i)′=ampG (i)*(1−a), when the W (i) is 0;
where a is a given positive real number less than 1 and i is the ith bit of the information embedded.
3. The method according to claim 1 , wherein the step of extracting the information embedded out from the printed information so as to determine whether surface information of the printed information is falsified comprises the following steps:
obtaining an image information B2 of the printed information;
performing the gray transformation on the image information B2 to obtain an image information GB2 after the gray transformation;
performing the frequency domain transformation on the image information GB2 after the gray transformation to obtain an amplitude ampGB2;
comparing the amplitude ampGB2 with an amplitude ampG in a database to obtain embedded information Wx having m bits in total, wherein the information of the ith bit is as follows:
when ampGB2 (i)>ampG (i)>=0, Wx (i)=1;
when ampGB2 (i)>ampG (i)<0, Wx (i)=0;
comparing the embedded information Wx having the m bits with embedded information W having m bits in the database so as to determine whether the surface information of the printed information is falsified; and
performing two-dimensional code reading on the image information B2 or the image information GB2 after the gray transformation, and comparing with two-dimensional code information in the database so as to determine whether the two-dimensional code read on the image information B2 or the image information GB2 is falsified.
4. The method according to claim 3 , further comprising: before the gray transformation is performed on the image information B2, preprocessing the image information B2.
5. The method according to claim 3 , wherein a sequence of 0 and 1 for the m bits of the embedded information W is composed of information by direct conversion, or is composed of encrypted or additionally verified codes, or is combined with the two-dimensional code information.