Hewlett-packard Company

Cirrus Logic Inc.

Stream Machine Company

Konstantinos Konstantinides

Daniel R Tretter

Vasudev Bhaskaran

Giordano Bruno Beretta

Balas K Natarajan

Gadiel Seroussi

Qian Lin

Andrew J Patti

Alexander I Drukarev

Linjun Zhou

Shaomei Chen

A communication system is disclosed in one embodiment of the present invention to include an encoder circuit responsive to an audio signal for performing compression on the audio signal and adaptive to generate an audio output signal based upon the compressed audio signal, the encoder circuit for sampling the audio signal to generated sampled signals, each sampled signals having a real and an imaginary component associated therewith, each sampled signal having an energy and a phase defined within a current block and each sampled signal being transformed to have a real and an imaginary component, a previous block preceding the current block and a block preceding the previous block, the encoder circuit for calculating the phase of the samples of the current block using the real and the imaginary components of the samples of the previous block and the block preceding the previous block, wherein calculations for determining the unpredictability measure is reduced by avoiding trigonometric calculations of the sampled signals of the current block thereby improving system performance.

Fast implementation of MPEG audio coding

Video signal post-processor de-blocks signal by processing block edges, particularly vertical and/or horizontal neighboring pixels. Depending on boundary condition, received signal is filtered using smoothing LPF function. Low-memory post-processor system neither requires DCT block characteristics nor blurs image edges close to block boundary.

Postprocessing system for removing blocking artifacts in block-based codecs

An image compression system for compound images containing both text and pictures. The system is capable of receiving the images on a non-overlapping 8 by 8 pixel blank basis and includes a discrete cosine transformer connected to a quantizer drawing lossy quantization factors from quantization tables. The lossy quantization factors are modified by a variable quantization subsystem based on the frequency of changes in the block to provide low lossy quantization factors for high frequency of changes and high lossy quantization factors for low frequency of changes. The high frequency of changes being indicative of text and the low frequency of changes being indicative of pictures. The quantizer is connected to an entropy coder using lossless entropy encoding factors from Huffman tables to provide JPEG compliant files.

System for variable quantization in JPEG for compound documents

A red-eye reduction system is described that includes a masking module. The masking module converts an image into a mask having first state areas representing red color pixels of the image and second state areas representing other color pixels of the image. The image includes an eye with a red pupil. A pupil locating module is coupled to the masking module to locate a substantially first state area in the mask that resembles a pupil. A color replacing module is then coupled to the pupil locating module to change the red color pixels in the area into monochrome (grey) or other predefined colors. The color replacing module also adjusts the boundary of the area by changing the colors of pixels in close proximity to the area if the color of these pixels is determined to be sufficiently close to red such that natural appearance of the eye is maintained when reducing the red pupil. A method of reducing red-eye effect in a digital image is also described.

Apparatus and a method for reducing red-eye in a digital image

A method of compressing color source image data includes forming a quantization table with a 'supra-threshold' term. This method includes a step of selecting a set of target images, where each target image includes one or more image elements such as text. These image elements are then analyzed to identify those that are more important for visual quality. These 'supra-threshold' terms are then selected that gives a larger weight to the quantization table elements that correspond to important image elements and a smaller weight to the table elements that correspond to less important image elements. This process selectively weights the characteristics of each DCT basis vectors. By giving larger weights to the table elements that correspond to the 'up-downness' of the image, i.e., the vertical attributes of the image elements, and the 'left-rightness' of the image, i.e., the horizontal attributes of the image elements, and smaller weights to the table elements corresponding to the 'criss-crossedness' of the image, i.e., the diagonal attributes of the image elements, the visual quality of an image that includes text can be preserved while significantly increasing the compression ratio.

Method for selecting JPEG quantization tables for low bandwidth

The text and image enhancing technique according to the invention is integrated into the decoding or inverse quantization step that is necessarily required by the JPEG standard. The invention integrates the two by using two different quantization tables: a first quantization table (Q.sub.E) for use in quantizing the image data during the compression step and a second quantization table used during the decode or inverse quantization during the decompression process. The second quantization table Q.sub.D is related to the first quantization table according to a predetermined function of the energy in a reference image and the energy in a scanned image. The energy of the reference image lost during the scanning process, as represented by the energy in the scanned image, is restored during the decompression process by appropriately scaling the second quantization table according to the predetermined function. The difference between the two tables, in particular the ratio of the two tables, determines the amount of image enhancing that is done in the two steps. By integrating the image enhancing and inverse quantization steps the method does not require any additional computations than already required for the compression and decompression processes.

Text and image sharpening of JPEG compressed images in the frequency

A coding system for data compression and decompression of a digitized source signal, for example in accordance with the MPEG audio standard, includes an analysis filter in which an inverse discrete cosine transform operation is employed during data encoding, and a synthesis filter in which a discrete cosine transform is performed during data decoding.

Fast subband filtering in digital signal coding

Although data compression methods exist in the prior art, some of which would result in an optimal number of piecewise linear approximation segments for the compressed output signal, these compression methods require complicated calculations and data processing that inhibit real time signal processing and portability in hardware implementation. A novel method for signal compression with a known level of loss by selecting a level of acceptable error is described. With this new compression method, the number of additional approximation segments to its compressed output signal is generally 50% more than the optimal number obtained in the prior art. However, its processing simplicity allows for improved real time signal processing and simplified practical hardware implementation.

Simplified method and apparatus for loss signal compression

A method of transforming a multi-beam ultrasonic image in which a plurality of ultrasonic beams are simultaneously transmitted into an object along a plurality of lines and across a plurality of arcs. The reflected signals are sensed along each line and sampled thereby creating an image matrix of sampled values taken from the intersection of each line and arc. For each image value, a linear combination of surrounding values is formed to create a transformed image value which reduces the effect of interbeam interference.

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San Jose, CA, United States of America

Konstantinos Konstantinides