The FBI has been collecting fingerprint cards since 1924 and now has over 200211u001emillion of them. Digitized with 8 bits of grayscale resolution at 500 dots per 211u001einch, it means 2000 terabytes of information. Also, without any compression, 211u001etransmitting a 10 Mb card over a 9600 baud connection will need 3 hours. Hence we 211u001eneed a compression and a compression as close to lossless as possible : all 211u001efingerprint details must be kept. A lossless compression usually do not give a 211u001ebetter compression ratio than 2:1, which is not sufficient. Compressing these 211u001eimages with the JPEG standard leads to artefacts which appear even at low 211u001ecompression rates. Therefore the FBI has chosen in 1993 a scheme of compression 211u001ebased on a wavelet transform, followed by a scalar quantization and an entropy 211u001ecoding : the so-called WSQ. This scheme allows to achieve compression ratios of 211u001e20:1 without any perceptible loss of quality.
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