METHOD AND SYSTEM FOR SCRAMBLING AND DESCRAMBLING A DIGITAL IMAGE

摘要

The present invention refers to a method for scrambling an original digital image into a scrambled image and for descrambling the scrambled image into a reconstructed image. The method firstly comprises a scrambling operation for substituting a plurality of original coefficients by dummy coefficients, while safeguarding the coding format, and for storing the substituted original coefficients with their respective position, as original data into at least two control objects, each control object corresponding to a specific degradation level of the original image. This method secondly comprises a descrambling operation for receiving the scrambled image and at least a part of said control objects, and for using original data derived from a selection of at least one of said control objects, performed on the basis of a user access condition, to obtain the reconstructed image by putting back the original coefficients instead of said dummy coefficients thanks to their respective position.

主权项

1. A method for scrambling an original digital image into a scrambled image and for descrambling the scrambled image into a reconstructed image, said original image being defined, according to a coding format, by a set of orderly original coefficients which refer to coding elements arranged in blocks with in this image and/or to parameters of said coding format within a conversion table, the method comprising a scrambling operation and a descrambling operation;
the scrambling operation comprising the steps of: substituting a plurality of said original coefficients by dummy coefficients of the same nature so as to safeguard said coding format; and storing the substituted original coefficients with their respective position, as original data into at least two control objects, each control object corresponding to a specific degradation level of the original image; the descrambling operation comprising the steps of: receiving the scrambled image and at least a part of said control objects; and using original data derived from a selection of at least one of said control objects, performed on the basis of a user access condition, for obtaining the reconstructed image by putting back the original coefficients instead of said dummy coefficients, by means of their respective position.