摘要:
The present disclosure relates generally to embedding auxiliary data and data hiding. One claim recites a method including: receiving data representing a media signal; using a programmed electronic processor, calculating perceptibility characteristics of the media signal, in which the perceptibility characteristics include contrast; using a programmed electronic processor, calculating a non-linear contrast to gain mapping using the perceptibility characteristics; using a programmed electronic processor, embedding an auxiliary signal in the media signal with reference to the non-linear contrast to gain mapping. Other claims and combinations are also provided.
摘要:
A perceptual model performs an analysis of a media signal, such as an image or audio signal. The model may be used in media signal processing applications such as digital watermarking and data compression to reduce perceptibility of changes made to code the signal. For image applications, the model computes the sensitivity of an image to changes based upon local image contrast, while taking into account the sensitivity of connected directional edges. By comparing the local image strength of various directionally filtered versions of the image, the model creates a directional control vector. This control vector may be used to reduce changes to an image in text and edge regions, and thus, avoid perceptible artifacts in those regions. The model takes into account the local contrast of the image and the directional control vector to create a gain vector. Using the local contrast measurements, the model follows the eye's nonlinear response to contrast discrimination.
摘要:
The present disclosure relates generally to embedding auxiliary data and data hiding. One claim recites a method including: receiving data representing a media signal; using a programmed electronic processor, calculating perceptibility characteristics of the media signal, in which the perceptibility characteristics include contrast; using a programmed electronic processor, calculating a non-linear contrast to gain mapping using the perceptibility characteristics; using a programmed electronic processor, embedding an auxiliary signal in the media signal with reference to the non-linear contrast to gain mapping. Other claims and combinations are also provided.
摘要:
A perceptual model performs an analysis of a media signal, such as an image or audio signal. The model may be used in media signal processing applications such as digital watermarking and data compression to reduce perceptibility of changes made to code the signal. In one implementation, a method of reducing human perceptibility of visible artifacts attributable to embedding a digital watermark in a media signal is provided. The method determines a contrast measurement for local areas of the media signal; adjusts a contrast measurement for a local area if the contrast measurement is above a predetermined level; and embeds the digital watermark in the local areas in a manner determined at least in part by their respective contrast measurement.
摘要:
The present invention relates to digital watermarking. In one implementation, a system is provided to read a digital watermark from digital imagery which includes data representing a number of pixels. Each pixel of the number of pixels is defined by a set of values representing color components of the particular pixel. The digital watermark is embedded in the digital imagery through modifications to at least some data representing the digital imagery. The system includes a filter to calculate values of pixels along a preferred projection axis, the preferred projection axis corresponds to a direction of embedding determined based on color characteristics of at least some pixels associated with the digital imagery; and a digital watermark reader which operates on values calculated by the filter. Other implementations are provided as well.
摘要:
The present invention relates generally to embedding auxiliary data and data hiding. One claim recites a method including: calculating with a processor or electronic circuitry characteristics of a media signal comprising audio or video; based at least in part on calculated characteristics of the media signal, providing a map of the media signal, wherein the map identifies at least one portion of the media signal in which plural-bit data should be steganographically encoded; transforming at least some portions of the media signal into a transform domain; and steganographically encoding with a processor or electronic circuitry auxiliary data in data representing at least the one portion of the media signal in which the plural-bit data should be steganographically encoded, and wherein at least said act of transforming or said act of steganographically encoding utilizes the map of the media signal. Other claims and combinations are also provided.
摘要:
A perceptual model performs an analysis of a media signal, such as an image or audio signal. The model may be used in media signal processing applications such as digital watermarking and data compression to reduce perceptibility of changes made to code the signal. For image applications, the model computes the sensitivity of an image to changes based upon local image contrast, while taking into account the sensitivity of connected directional edges. By comparing the local image strength of various directionally filtered versions of the image, the model creates a directional control vector. This control vector may be used to reduce changes to an image in text and edge regions, and thus, avoid perceptible artifacts in those regions. The model takes into account the local contrast of the image and the directional control vector to create a gain vector. Using the local contrast measurements, the model follows the eye's nonlinear response to contrast discrimination.
摘要:
The present invention relates generally to embedding auxiliary data and data hiding. One claim recites a method including: calculating with a processor or electronic circuitry characteristics of a media signal comprising audio or video; based at least in part on calculated characteristics of the media signal, providing a map of the media signal, wherein the map identifies at least one portion of the media signal in which plural-bit data should be steganographically encoded; transforming at least some portions of the media signal into a transform domain; and steganographically encoding with a processor or electronic circuitry auxiliary data in data representing at least the one portion of the media signal in which the plural-bit data should be steganographically encoded, and wherein at least said act of transforming or said act of steganographically encoding utilizes the map of the media signal. Other claims and combinations are also provided.
摘要:
Slight camera movement between capture of successive images is advantageously utilized to minimize or eliminate the need to interpolate in order to fill in the “holes” in a Bayer pattern. The captured color values from multiple appropriately positioned images are used to fill these holes. For example, instead of interpolating the value of red for the second pixel position on the first row of a Bayer pattern, an image is selected which is positioned one pixel to the right of the first image, and the red vales from this image are used for the red values of the second pixel on the first line. Values of the pixels in multiple images which are appropriately aligned to each pixel position are averaged to generate a better value for each pixel position. Information carried by a digital watermark (either alone or together with other techniques) is used to determine the alignment of the images. Images are selected which are positioned so that corresponding pixels fall within a specified tolerance from a location in a Bayer pattern. The pixel values of the images which fall within the specified tolerance of each pixel position in a Bayer pattern are selected and used for the alignment.
摘要:
This disclosure describes methods for using embedded auxiliary signals in documents for copy detection and other applications. In on application, the auxiliary signal is formed as an array of elements selected from a set of print structures with properties that change differently in response to copy operations. These changes in properties of the print structures that carry the embedded auxiliary signal are automatically detectable. For example, the changes make the embedded auxiliary signal more or less detectable. The extent to which the auxiliary data is detected forms a detection metric used in combination with one or more other metrics to differentiate copies from originals. Examples of sets of properties of the print structures that change differently in response to copy operations include sets of colors (including different types of inks), sets of screens or dot structures that have varying dot gain, sets of structures with different aliasing effects, etc. Robust and fragile watermarks are used in Image Replacement Documents for a variety of applications. Digital watermarks act as on-board mediators in authentication of a variety of printed documents. Finally, digital watermarks are used to help manage quality of the scanners used in imaging systems.