摘要:
Methods are provided for creating a fluorescent watermark within an image on a substrate, such as paper. The method involves creating a halftone image using two different halftone strategies. The halftone method is combined with a binary watermark mask to form two color patterns (e.g., one in a background region of the image and one in a watermark region of the image) and two successive-filling halftone algorithms, such that the ink droplets deposited by one color pattern cover more of the substrate than the ink droplets deposited by the other color pattern, with the two color patterns having approximately the same reflectance under normal light. However, under UV illumination, a visible difference (e.g., the watermark) is seen in the two patterns.
摘要:
Disclosed are systems and methods directed to digital watermarks, and more particularly, the generation of invisible correlation-based digital watermarks embedded in halftone images.
摘要:
A method for generating an authenticable color image, the color image including a plurality of color separations, wherein an authentication image inserted in the multicolor image is not readily visually perceptible, includes halftoning image data corresponding to a first color separation using a single halftone screen, wherein the halftone screen includes means for generating an authentication image in a color image; and halftoning image data corresponding to a second color separation using the halftone screen and dot placement information for the image data corresponding to the first color separation to form a multicolor image; wherein halftoning of image data corresponding to the second color separation includes placing dots for the second color separation in thresholds of the halftone screen relative to those thresholds occupied by the first color separation in the halftone screen in accordance with a predetermined relationship.
摘要:
Disclosed are moiré-free color halftoning methods, apparatus and systems to digitally reproduce an original color image. The disclosed embodiments are particularly useful for rendering a color image with a color printing device. According to one exemplary embodiment, an image forming method utilizes three or four rotated hexagonal screens which can include regular shaped hexagon screens or convex tessellated hexagon screens.
摘要:
Methods and systems for utilizing conjugate cluster halftone screens to embed patterns or images as invisible watermarks into both digital halftone image files and corresponding printed documents are disclosed. In general, two or more two-conjugate halftone screens can be configured to provide a basic information carrier for embedding a digital watermark into a document. Thereafter, one or more clusters can be created from the two-conjugate halftone screens, wherein such clusters include the same centroid position relative to a grid defined by fundamental halftone frequencies. Two halftone patterns can then be blended from the two-conjugate halftone screens in a cluster-to-cluster basis so that virtually no loss of image quality occurs in comparison with an output of either the two-conjugate halftone screens, thereby permitting the digital watermark to be embedded into the document utilizing the two-conjugate halftone screens.
摘要:
The present invention relates to the manipulation of differential gloss as may be inherent in halftoned images by utilization of tags. By selectively applying halftones with anisotropic structure characteristics, which are significantly different in orientation while remaining identical in density, as directed by tag settings, a gloss image may be superimposed within an image without the need for special toners or paper. Conventional copier systems will not typically be able to copy such a superimposed gloss image.
摘要:
A method for characterizing a printing device response for a halftone screen includes (a) generating a plurality of test patches, each test patch comprising a dot pattern having less than three different base patterns for the halftone screen; (b) measuring the luminance of selected ones of the test patches; (c) plotting the luminance measurements to provide a set of calibrated points on a printer calibration curve; and (d) generating the printer calibration curve between adjacent calibrated points using an equation establishing a relationship between ink area coverage and reflectance of the image.
摘要:
Visible digital watermarks enable a robust tracking method to be associated with one or more input images. Specifically, by modifying a halftone screen within a certain area by setting a gray-scale range within that area to a threshold, and halftoning an input image based on this modified halftone screen, visible watermarks can be embedded into an input image.
摘要:
A system and method for digital watermark embedding and retrieval using phase shift stoclustic (stochastically clustered) screens. Watermarks are embedded based on the phase shift of clustered halftone screens. Therefore, the hidden information, or invisible watermark, can be detected and visualized by correlating clusters as opposed to the pixel-based correlation required by other methods. Therefore, the detection of watermarks is much easier, especially when distortions have been introduced into the embedded image. By replacing regular cluster halftone screens with stoclustic screens for hidden watermarks, watermarks can quickly be embedded and retrieved
摘要:
As set forth herein, computer-implemented methods and systems facilitate halftoning using a parametrically controlled spot function based on triangle tessellation, which in turn facilitates dot growth control of periodic halftone using an irregular seed structure. The spot function determines the shape of the halftone dot used to reproduce a given pixel. The spot function is well suited for growing halftone dots arrayed on a non-regular grid and can also be used for grids with regular order. The spot function includes adjustable parameters for controlling its sharpness and slope.