Ecole De Technologie Superieure

At+t Corp.

At&t Intellectual Property I, L.p.

Ecole De Technologie Superieur

Steven Pigeon

Stéphane Coulombe

Leon Bottou

Jean-François Franche

Jean-Francois Franche

Method and system for determination of a metric measuring a difference between two image blocks used in motion compensated video coding of scenes are described. Only selected pixels in a block in the scene are processed for enhancing the speed of the metric computation.

Method and system for determining a metric for comparing image blocks in motion compensated video coding

Several quality-aware transcoding systems and methods are described, in which the impact of both quality factor (QF) and scaling parameter choices on the quality of transcoded images are considered in combination. A basic transcoding system is enhanced by the addition of a quality prediction look-up table, and a method of generating such a table is also shown.

System and method for quality-aware selection of parameters in transcoding of digital images

Method and system for low complexity transcoding of images with near optimal quality for display on a terminal are presented. Generating effective transcoding parameters prior to transcoding and retrieving the transcoding parameters based on the features of the input image and the characteristics of the terminal, an output image quality close to that produced by optimal quality transcoding is achieved. The processing time is much smaller in comparison to that required for optimal quality transcoding.

Method and system for low complexity transcoding of image with near optimal quality

A method for quality-aware transcoding of an input image into an output image for display on a terminal having device file size and image size constraints are disclosed. The method extracts features of the input image including dimensions and file size of the input image, predicts a file size of the output image taking into account constraints of the terminal and extracted features, including selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal, determines quality metric values of the output image, characterizing a measure of distortion of the input image introduced by the transcoding, corresponding to the feasible transcoding parameters in the set of feasible transcoding parameters, and selects those transcoding parameters from the set of feasible transcoding parameters, which yield the highest quality metric value. A corresponding system is also provided.

A system and method for predicting a file size of an image subject to transformation by scaling and a change of at least one quality-controlling parameter are described. The system receives the file size of the image before transformation, information about at least one quality-controlling parameter of the image before transformation, information about at least one quality-controlling parameter and a scaling factor to be applied to the image during transformation. A relative size prediction is calculated using the received quality-controlling parameters information and the scaling factor. The file size of the image after the transformation is finally calculated as a function of the file size of the image before the transformation and the calculated relative size prediction. Images are partitioned into classes of images, and for each class of images, an array of relative file size predictions, having at least two dimensions, is computed.

System and method for predicting the file size of images subject to transformation by scaling and a change of quality-controlling parameters

Method and system for low complexity transcoding of images with near optimal quality

Method and system for generating a quality prediction table for quality-aware transcoding of digital images

A system and method for predicting a file size of an image subject to transformation by scaling and a change about at least one quality-controlling parameter, in which an input receives (a) the file size of the image before transformation, (b) information about at least one quality-controlling parameter of the image before transformation, (c) information about at least one quality-controlling parameter for application to the image during transformation, and (d) a scaling factor for application to the image during transformation. A relative size prediction is calculated on the basis of the received quality-controlling parameters information and scaling factor. The file size of the image after transformation is finally calculated as a function of the file size of the image before transformation and the calculated relative size prediction.

Wavelet coding of partially-masked image information may be made faster by either of two embodiments of the present invention. In a first embodiment, quick convergence is obtained by performing wavelet encoding in stages, each stage associated with a predetermined wavelet scale. By advancing the stages from finest scale to coarsest scale, coefficients of masked wavelets are identifies early in the coding process. In a second embodiment, quick convergence is obtained by introducing overshoot techniques when masked coefficients are identified, modified and image data is reconstructed therefrom.

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Steven Pigeon