METHOD AND SYSTEM MAKING IT POSSIBLE TO VISUALLY ENCRYPT THE MOBILE OBJECTS WITHIN A COMPRESSED VIDEO STREAM

Method of protecting at least one part of a video stream or of a compressed video sequence against a violation of the information contained in said stream, said stream being able to be decomposed into at least one first type of objects and one second type of objects, the method being applied to a selection of images contained in said video sequence, characterized in that it comprises at least the following steps: analyzing the video sequence in the compressed domain so as to define for a given image N at least one first type of objects to be protected by encryption and a second type of objects (1, 2), the analysis module which identifies the portions of the image belonging to the first type of objects to be protected sends the motion estimation vectors and the transformed coefficients to the encryption step, determining, according to the partitioning into portions or into groups of portions of the existing image N (3b, 3a), those corresponding respectively to the first type of objects to be protected (3b) and to the other types (3a), encrypting at least a part of the first type of objects (5a), reconstructing on the basis of the outputs of the previous steps a stream composed of at least one first type of encrypted objects and of other types of objects, to which is added information indicating which objects are the ones that have been encrypted. System making it possible to implement the method. Método para proteger por lo menos una parte de un flujo de vídeo o una secuencia de vídeo comprimida contra la violación de información contenida en el flujo, este flujo puede descomponerse en por lo menos un primer tipo de objetos y un segundo tipo de objetos. El método se aplica en una selección de imágenes contenidas en la secuencia de vídeo, y se caracteriza porque comprende por lo menos una de las siguientes etapas: analizar la secuencia de vídeo en el dominio comprimido, a fin de definir para una imagen N determinada por lo menos un primer tipo de objetos a proteger mediante encriptación y un segundo tipo de objetos, (1, 2), el módulo de análisis que identifica las porciones de la imagen que pertenecen al primer tipo de objetos a proteger, envía vectores de cálculo de los movimientos y los coeficientes transformados en la etapa de encriptación, determinar, según la división en porciones o en grupos de porciones de la imagen (3b, 3a) N existente, aquéllas que corresponden respectivamente al primer tipo de objetos a proteger (3b) y a otros tipos (3a), encriptar