Image enhancement on JPEG compressed image data

摘要

A method and apparatus are provided for enhancing JPEG compressed digital image data wherein only the DC components of the compressed image data are required to obtain a statistical subsampling of the corresponding uncompressed image data. JPEG compressed image data are received that represent an input digital image, and the JPEG compressed image data include a plurality of DC components. DC components are extracted from the JPEG compressed image data, and the extracted plurality of said DC components represent a subsampling of the input digital image. At least some of the plurality of extracted DC components are input to an automated image enhancement system. The DC components input to the automated image enhancement system are used to derive at least one of a final correction tone reproduction curve and a sharpness filter for enhancement of the input digital image represented by the JPEG compressed data. The final correction tone reproduction curve and/or sharpness filter are bound to the JPEG compressed image data for subsequent use in enhancing the input digital image represented by the JPEG compressed image data after the JPEG compressed image data have been decompressed.