Dwsq14 takes as input a file containing a WSQ14-compressed grayscale fingerprint image from NIST Special Database 14. The version of WSQ14 used to compress the images on this database is not certified and produces loss that may be more than permitted by a certified WSQ compression algorithm. Once read into memory, the lossy-compressed pixmap is decoded and reconstructed using Wavelet Scalar Quantization as described in the FBI's Criminal Justice Information Services (CJIS) document, "WSQ Gray-scale Fingerprint Compressions Specification," Dec. 1997. This is the only fingerprint compression format accepted by the FBI IAFIS system.
Upon completion, two different output image file formats are possible, a NIST IHead file (the default) or a raw pixmap file (specified by the -raw_out flag). In addition, a specially formatted text file, called a NISTCOM, is created with extension ".ncm". The NISTCOM file contains relevant image attributes associated with the decoded and reconstructed output image. (See NISTCOM OUTPUT below.)
All switch names may be abbreviated; for example, -raw_out may be written -r.
the extension of the decompressed output file. To construct the output filename, dwsq14 takes the input filename and replaces its extension with the one specified here.
the input WSQ14 file to be decompressed.
specifies that the decoded and reconstructed image should be stored to a raw pixmap file.
Upon successful completion, dwsq14, creates a specially formatted text file called a NISTCOM file. A NISTCOM is a text-based attribute list comprised of (name, value) pairs, one pair per text line. The first line of a NISTCOM always has name = "NIST_COM" and its value is always the total number of attributes included in the list. These attributes are collected from two sources and merged to represent the history and condition of the resulting reconstructed image. The two sources for the attributes are the IHEAD header of the compressed image (specific information about the fingerprint itself is contained here) and the decompression process. In general, attribute values from the second source are given precedence over those from the first.
The NISTCOM output filename is constructed by combining the basename of the input WSQ14 file with the extension ".ncm". By creating the NISTCOM file, relevant attributes associated with the decoded and reconstructed image are retained and easily accessed. This is especially useful when dealing with raw pixmap files and creating image archives. The following is an example NISTCOM generated by dwsq14 (highlighted items specific to SD14):
NIST_COM 12 PPI 500 SD_ID 14 HISTORY f0000001.wsq 20 tape3.t1116010.01 4096x1536 FING_CLASS R SEX m SCAN_TYPE i PIX_WIDTH 832 PIX_HEIGHT 768 PIX_DEPTH 8 LOSSY 1 COLORSPACE GRAY