Patent ID: 7103237

Claim:
A method of indexing a digital image comprising a plurality of blocks, comprising the following steps: generating a first information item characteristic of the visual content of the image; generating a second information item from the first information item, wherein the second information item is indicative of a degree of significance of the visual content of at least one of the plurality of blocks with respect to the overall content of the image and thereby characteristic of the spatial distribution of the visual content of the image in its image plane; and associating, with the image, an index composed of the first information item and the second information item, wherein said step of generating the first information item comprises the following substeps: dividing the image plane of the image according to a partitioning comprising the plurality of blocks, the plurality of blocks comprising a predefined number N of blocks; extracting, from each of the blocks, a data item of a first type representing at least one characteristic of the visual content of the block under consideration; and generating the first information item as being a vector having N components, each of which is one of the data items of the first type, wherein said step of generating the second information item comprises the following substeps: calculating, for each of the blocks, a data item of a second type indicative of a degree of significance of the visual content of the block under consideration with respect to the overall content of the image; generating the second information item as being a vector having N components, each of which is one of the data items of the second type, and wherein for each of the blocks, the data item of a second type, indicative of a degree of significance of the visual content of the block under consideration with respect to the overall content of the image, is obtained by applying the following formula: w i Im =  h i Im  ∑ i = 1 N ⁢  h i Im  according to which the data item of the second type (w i Im ) is obtained by calculating the ratio between the Euclidean norm of the data item of the first type associated with the block under consideration and the sum of the Euclidean norms of the data items of the first type associated with all the blocks of the image.