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US 2003/0229643 A1Published application
Creating a footprint of a computer file
AssigneeDigimarc Corporation
InventorThomas Huguenard
Life of this patent
Estimating the term…
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AssigneeDigimarc Corporation
InventorThomas Huguenard
Estimating the term…
A method and system for identifying files by calculating a unique table of values for the file. The calculated values in the table constitute a “footprint” of the file. A first embodiment works for any type of files. A second embodiment is particularly useful in identifying image files. In the first embodiment, for each possible value of the bytes that form the file, the offset of the first occurrence of a byte with the particular value, the offset of the last occurrence of a byte with the particular value, and the number of occurrences of the bytes with the particular value are calculated. These values are stored in a table and termed prominence values. The prominence values uniquely identify the file. In a second embodiment, an image file is broken into relatively small cells. The cells with the highest and lowest average values of quantities such as luminance, red chrominance, etc. are determined. The cells with these values are the prominences for the particular image. Vectors which describe the location of the prominence cells are calculated and saved. The values of the various quantities in the prominence cells and the vectors pointing to the location of these cells provide a footprint for the image.
1) A method of calculating a footprint of a file which uniquely identifies the file, said file containing a number of bit sequences of length n bits, each of which has a number (2N) of possible values, said method including the steps of, determining for each possible particular value of a bit sequence, the number of times a bit sequence having said particular value occurs in said file, and recording the number of times said particular value occurred along with the offset of the first and last occurrence of said particular value, whereby said recorded values form a footprint of said file.
2) A method of calculating a footprint for an image file comprising the steps of dividing said image into cells,
8) A method of calculating a set of values which constitute a footprint for an image, said method comprising the steps of
9) A method of calculating a set of values which uniquely identifies a file, said file containing a number of bytes, each of which has 256 possible values, said method including the steps of,
10) A system for calculating a set of values which constitute a footprint for an image, said system including a program for
13) A method of calculating a set of values which uniquely identifies a file, said file containing a number of bytes, each of which has a plurality of possible values, said method including the steps of,
16) A system that calculates a footprint of a file, said footprint uniquely identifying said file, said file containing a number of bit sequences of length N bits, each of which has a number (2N) of possible values, said system including a computer program which determines for each possible particular value of a bit sequence, the number of times a bit sequence having said particular value occurs in said file, and recording the number of times said particular value occurred along with the offset of the first and last occurrence of said particular value, whereby said recorded values form a footprint of said file.
Dependencies are inferred from the claim text.