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Title: Methods and apparatus for hiding data in halftone images
Authors: Au, Oscar C.
Fu, Ming Sun
Keywords: Halftone image
Watermark data
Hidden data
Embed information
Issue Date: 6-Jun-2006
Citation: US Patent 7,058,199 B1, 2006
Abstract: Halftoning is a method to represent multi-tone images using only two-tone colors. Such methods are used widely in computer printers, newspaper/magazine/book publishing, fax machines, etc. From a distance, halftoned images resemble images with multi-tones. This new invention uses Data Hiding Error Diffusion (DHED) and Data Hiding by Smart Pair Toggling (DHSPAT), to hide a potentially large amount of watermarking data in halftone images with either minor or negligible perceptual degradation. The two methods are used in different situations. One situation is when the original multi-tone image is available and error diffusion method is adopted, i.e. the DHED. Another situation is when both the original multi-tone image and the halftoning method are not known. When only the halftone image is available, the DHSPAT should be adopted. DHED gives very high visual quality and has low complexity. DHSPAT is even simpler in complexity, though with comparatively slightly lower quality, it is still visually sound.
Rights: This patent is also available at HKUST Technology Transfer Center Patent Search at <>
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