Xerox Corporation

Microsoft Technology Licensing, LLC

Ricardo L De Queiroz

Reiner Eschbach

Thyagarajan Balasubramanian

Zhigang Fan

Karen Marie Braun

Philip Andrew Chou

Robert Roy Buckley

William A Fuss

Robert P Loce

Steven Jay Harrington

Raja Bala

R Victor Klassen

Wencheng Wu

Shen-Ge Wang

Jiebo Luo

Dennis Lee Venable

James E Bollman

Trac D Tran

Gozde Bozdagi

Patrick A Fleckenstein

G&ouml;zde Bozdagi

Disclosed herein are exemplary embodiments of innovations in the area of point cloud encoding and decoding. Example embodiments can reduce the computational complexity and/or computational resource usage during 3D video encoding by selectively encoding one or more 3D-point-cloud blocks using an inter-frame coding (e.g., motion compensation) technique that allows for previously encoded/decoded frames to be used in predicting current frames being encoded. Alternatively, one or more 3D-point-cloud block can be encoded using an intra-frame encoding approach. The selection of which encoding mode to use can be based, for example, on a threshold that is evaluated relative to rate-distortion performance for both intra-frame and inter-frame encoding. Still further, embodiments of the disclosed technology can use one or more voxel-distortion-correction filters to correct distortion errors that may occur during voxel compression. Such filters are uniquely adapted for the particular challenges presented when compressing 3D image data. Corresponding decoding techniques are also disclosed.

Motion-compensated compression of dynamic voxelized point clouds

Innovations in scalable compression and decompression of point cloud data are described. For example, after an encoder uses a transform such as a region-adaptive hierarchical transform ('RAHT') on attributes of occupied points in point cloud data, the encoder separates transform coefficients into partitions. The partitions can be associated with different regions of a point cloud frame (spatial location scalability), different spatial resolutions of point cloud data (spatial resolution scalability), different reconstruction quality levels (SNR scalability), different point cloud frames organized in temporal layers (temporal resolution scalability), or different combinations of the preceding types of partitions. For decoding, a decoder can select all of the partitions or a subset of the partitions. The decoder decodes encoded data for the selected partitions, applying an inverse transform such as an inverse RAHT to transform coefficients for attributes of occupied points in point cloud data.

Scalable point cloud compression with transform, and corresponding decompression

Innovations in compression and decompression of point cloud data are described. For example, an encoder is configured to encode point cloud data, thereby producing encoded data. In particular, the encoder applies a region-adaptive hierarchical transform ('RAHT') to attributes of occupied points, thereby producing transform coefficients. The encoder can also quantize the transform coefficients and perform adaptive entropy coding of the quantized transform coefficients. For corresponding decoding, a decoder is configured to decode the encoded data to reconstruct point cloud data. In particular, the decoder applies an inverse RAHT to transform coefficients for attributes of occupied points. The decoder can also perform adaptive entropy decoding and inverse quantization of the quantized transform coefficients. The adaptive entropy coding/decoding can use estimates of the distribution of values for the quantized transform coefficients. In this case, the encoder calculates the estimates and signals them to the decoder.

Region-adaptive hierarchical transform and entropy coding for point cloud compression, and corresponding decompression

A system and method for authentication of JPEG image data enables the recipient to ascertain whether the received image file originated from a known identified source or whether the contents of the file have been altered in some fashion prior to receipt. A unique hashing function is derived from a first section of image data contained in the JPEG compressed image in such a way that any changes subsequently made to the first section of image data is reflected in a different hashing function being derived from a signature string is then embedded into a next section of the image data. Since the embedding of a previous section's integrity checking number is done without modifying the JPEG bit stream, any JPEG decoder can thereafter properly decode the image.

System for authentication of JPEG image data

A process for improving the reconstruction of images compressed by the wavelet-based JPEG2000 specification. The basic reconstruction is followed by an edge-preserving filter (such as a sigma filter), another transform to the wavelet domain, an adjustment in the wavelet domain to yield the same quantized values as the compressed input image, and, finally, an inverse wavelet transform to yield the improved image. The process reduces the artifacts in sharp text and graphics documents, yielding images that would otherwise require larger files.

Decompression with reduced ringing artifacts

A system and method for authentication of JPEG image data enables the recipient to ascertain whether the received image file originated from a known identified source or whether the contents of the file have been altered in some fashion prior to receipt. A unique hashing function is derived from a first section of image data contained in the JPEG compressed image in such a way that any changes subsequently made to the first section of image data is reflected in a different hashing function being derived from a signature string is ten embedded into a next section of the image data. Since the embedding of a previous section's integrity checking number is done without modifying the JPEG bit stream, any JPEG decoder can thereafter properly decode the image.

System and method for authentication of JPEG image data

A method is disclosed for converting color images to textured monochrome images such that image regions with similar luminance but different chrominance look different when converted to black-and-white to preserve color information therein. This texture-encoded color information can be extracted at a later time to reconstitute the original color image. The present method involves first converting the color image to a luminance-chrominance colorspace. The chrominance data is decomposed into 4 channels of chrominance. A wavelet transformation of the luminance channel is preformed. Scaled chrominance channels are then mapped to a number of wavelet sub-bands. Once mapped, the wavelet transform is inverted to generate textures proportional to the original colors of the color image having an amplitude proportional to the chroma of the original color. The black-and-white image is embedded with this texture information into the image's grayscale component. In order to retrieve the color image from the textured grayscale image, a wavelet transform regenerates the scaled chrominance channels mapped therein. Those wavelet sub-bands comprising embedded chroma are extracted and scaled to the size of the original image. The remaining sub-bands are inverted to produce the Y-image thereof. Separate images now exist in Y, Cr, and Cb. The recombination of the YCbCr images produce the colored image that was previously embedded into the grayscale components of the textured black-and-white image.

Method for embedding color image information into a black-and-white image

A system and method for authentication of JPEG image data enables the recipient to ascertain whether the received image file originated from a known identified source or whether the contents of the file have been altered in some fashion prior to receipt. A unique hashing function is derived from a first section of image data contained in the JPEG compressed image in such a way that any changes subsequently made to the first section of image data is reflected in a different hashing function being derived from a signature string is embedded into a next section of the image data. Since the embedding of a previous section's integrity checking number is done without modifying the JPEG bit stream, any JPEG decoder can thereafter properly decode the image.

A method enables a recipient of JPEG image data to authenticate the JPEG image data by producing a hashing function from a first section of the JPEG image data. A first integrity checking value is produced from the hashing function produced from the first section of JPEG image data and, from a least significant transmitted bit-plane of a second section of the JPEG image data, an embedded encrypted signature string is extracted and decrypted to generate a second integrity checking value. The first and second integrity checking values are compared and the first section of the JPEG image data is authenticated when the second integrity checking value matches the first integrity checking value.

Method for authentication of JPEG image data

What is disclosed is a decoding method for retrieving information bits encoded in a printed image comprising the steps of first receiving an input electronic image as a scanned version of the printed image. A region of interest in the image is then extracted and, for that region, an amount of K colorant present, denoted K; is obtained. Further, a color value is generated therefrom and the GCR used for encoding that region is determined using Kand the obtained color value. Encoded information bits are retrieved therefrom based on the determined GCR. The estimated Kis preferably evaluated conditional to a capacity signal Kand a luminance signal L. From the obtained data, values of K, K, and L, are derived wherein Kis estimated from a high resolution scan, and Kand L are estimated from a down-scaled image, respectively. The capacity signal Kand the luminance signal L are derived from the obtained color value. Further, the capacity signal, Kis derived by first applying a suitable operator S to reduce the image from scanner resolution to the watermark resolution and then converting the obtained color values to CMY estimates such that K=min(C,M,Y) Alternatively, K-capacity is derived from the amount, K, y, comprises first converting the obtained color values to CMY estimates and applying a suitable operator S to reduce the image from scanner resolution to the watermark resolution such that K=min(S(C),S(M),S(Y)); wherein L is described by a linear combination of scan signals RGB, such that L=kS(R)+kS(G)+kS(B). The value of Kis determined by first converting the obtained color values to CMY estimates. The estimates determine K-colorant amount at each pixel such that: K=min(C,M,Y). A suitable operator S is applied to reduce the image from scanner resolution to the watermark resolution.

System and method for digital watermarking in a calibrated printing path

This invention is a method and apparatus for processing decompressed images. More particularly, this invention relates to methods and apparatus which process images without requiring information on whether the image was previously compressed or how the image was compressed. Quantization values of each image block of a decompressed image are determined a compression method used to compress a decompressed image to be processed is identified. The method and apparatus of this invention is particularly useful to determine if a decompressed image was previously compressed using a JPEG compression technique by retrieving DCT coefficients and determining quantization values to determine original DCT coefficients of a compressed and decompressed image.

Maximum likelihood estimation of JPEG quantization values

This invention relates to a method and apparatus for image classification. More particularly, the present invention provides a technique to classify an image as a picture, a graphic or a mixed mode image. The classification is based on an approximation of a segmentation. The approximation is HVQ-LUT-based and outputs classification maps indicating whether pixels are background, text or pictures. Said classification maps are filtered to eliminate odd isolated samples and the resulting count of picture, text and background pixel is analyzed before concluding whether the image has pictorial, graphical or mixed contents.

Method and apparatus for image classification

What is disclosed is a method for digital watermarking in a calibrated printing path and comprises: first receiving a pixel possessing color values from an input image; receiving a plurality of information bits to be encoded at a corresponding pixel in an output image. Then, one of at least two different GCR functions are selected where the selection is based on the state of the received information bits. The number of GCR functions to be selected from is dependent on the number of possible states of the information bits intended to be encoded at each image pixel and preferably equals the number of states of the information bits intended to be encoded at each image pixel such that the GCR spatially varies across the output image. Further, at least two GCR functions are optimized to carry information and information bits intended to be encoded within the output image are represented with a tag. CMYK values are then generated using the selected GCR function and the color values. These CMYK values are assigned to a corresponding pixel in the output image. The information bits to be encoded at a given pixel indicate the type of object to which that pixel belongs, such as: graphics, picture, text, line art, etc. The output image, when printed, exhibits the property that substantially similar colors occurring at different spatial locations in the input image are produced with substantially different CMYK combinations in the print. Preferably, a parameterized function is used for the GCR function and the encoded state sets the parameter of the function. Information bits should be redundantly encoded throughout the output image. Regions that cannot be encoded by GCR information have to be compensated for. A reference mark is applied on the output image to indicate the starting point and order of the information sequence.

A color printing process, printing a color image in which out-of-gamut original colors are present. For each pixel defined by an original color which is determined to be out of gamut, a gamut remapping process is applied to map each pixel to a color which is within a printer gamut, remapping said pixels to colors within an output printer gamut. For a given set of gamut remapped pixels, gamut remapped pixel colors are compared with said original pixel colors, to derive a comparison metric. Using the comparison metric, a corrected set of gamut remapped colors is generated. The comparison metric may be subjected to an adaptive filtering process, which strengthens the comparison metric in high frequency image regions to increase its impact on the gamut remapped colors, and weakens the comparison metric in low frequency areas, to weaken its impact on the gamut remapped colors. The filter is selected by determining a filter selection metric in accordance with measured local image activity and changing filter parameters as a function of the determined filter selection metric.

Gamut mapping preserving local luminance differences with adaptive spatial filtering

A system is disclosed for enhancing resolution of compressed image data. All operations in the present invention are performed in the CCITT compressed domain. For the purpose of the present invention, the input image data is compressed which is mapped to the transitions of the input line. A line is interpolated between the input lines and the transitions of the interpolated line are determined according to the positional difference of transitions in input lines. The transitions of each line in resolution enhanced data are encoded into a compressed codes.

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Brasilia, Brazil

Ricardo L De Queiroz