APPARATUS AND METHODS FOR RECOMPRESSION OF DIGITAL IMAGES

摘要

A system and method for generating a second reduced size digital image from a first digital image, the method including iteratively compressing the first digital image to an extent determined by a quality measure comprising at least a blockiness measure quantifying added artifactual edges along coding block bom1daries of the second image and/or use of a quantization matrix generated by computing a weighted average of the quantization matrix of the first digital image and a scaled second quantization matrix.

主权项

1. A computerized method of enabling an image-adaptive, perceptually-lossless and near-maximal image compression, including:
compressing a first image giving rise to a second image; implementing a measure of added artifactual edges along coding block boundaries, including:
computing a difference image between the first and second images;defining a region within said difference image, said region comprising a plurality of coding blocks;within said region, computing for each boundary between two coding blocks a respective added-blockiness score indicating an extent of added artifactual edges along the respective boundary;computing a region quality score based on the added-blockiness scores computed for each boundary within the region; and determining based at least upon said region quality score whether a perceptual quality criterion is met by said second image.