Method and system for compressing digitized fingerprint images by a uniform degree of compression
First Claim
1. A method for achieving a desired value for the magnitude of compression when compressing the information contained in a digitized fingerprint image using a lossy compression method that includes use of a compression parameter whose value may be varied to adjust the amount of compression actually achieved, the method comprising:
- selecting a first value for the compression parameter;
performing a first compression of the information contained in a digitized fingerprint image using the first value for the compression parameter and using the lossy compression method, thereby producing a first set of compressed information;
computing a first value for the magnitude of compression from the quantity of information contained in the digitized fingerprint image and the quantity of information contained in the first set of compressed information;
forming a first pair of values which first pair includes the first value for the magnitude of compression and the first value for the compression parameter;
interpolating, using the first pair of values, a second pair of values, and a first new pair of values which first new pair includes the desired value for the magnitude of compression and an as yet unknown first new value for the compression parameter to determine a value for this first new value for the compression parameter by computing its value from the remaining five values; and
performing a first new compression of the fingerprint image information using this first new value for the compression parameter to produce a first new set of compressed information;
whereby the first new set of compressed information is compressed close to the desired value for the magnitude of compression.
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Accused Products
Abstract
A method and a system are described for achieving a desired value for the magnitude of compression when compressing the information contained in a digitized fingerprint images. A lossy compression method is used that includes use of a compression parameter whose value may be varied to adjust the amount of compression actually achieved. Briefly summarized, the method comprises selecting a first value for the compression parameter and then performing a first compression of the information contained in a digitized fingerprint image using the first value for the compression parameter and using the lossy compression method, thereby producing a first set of compressed information. Next, a first value for the magnitude of compression is computed from the quantity of information that is contained in the digitized fingerprint image and also from the quantity of information that is contained in the first set of compressed information. Then a first pair of values is formed which first pair includes the first value for the magnitude of compression and the first value for the compression parameter. Interpolation is then performed, using the first pair of values, a second pair of values, and a first new pair of values which first new pair includes the desired value for the magnitude of compression and an as yet unknown first new value for the compression parameter. In this interpolation, a value for this first new value for the compression parameter is determined by computing its value from the remaining five values. Finally, a new compression of the fingerprint image information is performed using this first new value for the compression parameter. This produces a new set of compressed information that is compressed close to the desired value.
35 Citations
30 Claims
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1. A method for achieving a desired value for the magnitude of compression when compressing the information contained in a digitized fingerprint image using a lossy compression method that includes use of a compression parameter whose value may be varied to adjust the amount of compression actually achieved, the method comprising:
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selecting a first value for the compression parameter; performing a first compression of the information contained in a digitized fingerprint image using the first value for the compression parameter and using the lossy compression method, thereby producing a first set of compressed information; computing a first value for the magnitude of compression from the quantity of information contained in the digitized fingerprint image and the quantity of information contained in the first set of compressed information; forming a first pair of values which first pair includes the first value for the magnitude of compression and the first value for the compression parameter; interpolating, using the first pair of values, a second pair of values, and a first new pair of values which first new pair includes the desired value for the magnitude of compression and an as yet unknown first new value for the compression parameter to determine a value for this first new value for the compression parameter by computing its value from the remaining five values; and performing a first new compression of the fingerprint image information using this first new value for the compression parameter to produce a first new set of compressed information; whereby the first new set of compressed information is compressed close to the desired value for the magnitude of compression. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system that can store, retrieve, transmit, and receive digitized fingerprint images and also compress and decompress such images, achieving a desired value for the magnitude of compression when compressing fingerprint images using a lossy compression method that includes use of a compression parameter whose value may be varied to adjust the amount of compression actually achieved, the system comprising:
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a programmed computer having a memory where fingerprint image information may be stored along with information identifying the individuals whose fingerprint images are stored in the memory, and also having a communications facility that can transmit and receive fingerprint image information to and from remote sites; compression routines installed on the programmed computer for carrying out at least one lossy method of compression that can compress digitized fingerprint images to facilitate their storage or transmission or both and that respond to adjustment of an incoming compression parameter argument by varying the degree of compression; decompression routines installed on the programmed computer for uncompressing digitized fingerprint images; and compression control routines installed on the programmed computer that contain instructions which call upon the compression routines and carry out steps comprising; selecting a first value for the compression parameter; calling upon the compression routines to perform a first compression of the information contained in a digitized fingerprint image using the first value for the compression parameter, thereby producing a first set of compressed information; computing a first value for the magnitude of compression from the quantity of information contained in the digitized fingerprint image and the quantity of information contained in the first set of compressed information; forming a first pair of values which first new pair includes the first value for the magnitude of compression and the first value for the compression parameter; interpolating, using the first pair of values, a second pair of values, and a first new pair of values which first new pair includes the desired value for the magnitude of compression and an as yet unknown first new value for the compression parameter to determine a value for this first new value for the compression parameter by computing its value from the remaining five values; and calling upon the compression routines to perform a first new compression of the fingerprint image information using this first new value for the compression parameter to produce a first new set of compressed information; whereby the first new set of compressed information is compressed close to the desired value for the magnitude of compression. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification