OP_WSQP: Compress DIB to WSQ

These codes implement parts of ANSI/NBS-CLS 1-1993, "American National Standard Data Format For The Interchange Of Fingerprint Information.''  Reference "WSQ Gray-scale Fingerprint Image Compression  Specification''  IAFIS-IC-0110v2, 16 Feb 1993 refers to a technical report ( probably written by T. E. Hopper, C. M. Brislawn, and J. N. Bradley) which is available over the internet  as ftp://ftp.c3.lanl.gov/pub/WSQ/documents/wsqSpec2.ps.Z

The Accusoft Corporation implementation of this specification is approved by the FBI and is assigned the FBI implementation number: 54100.

See the WSQ:OP_WSQP section for additional information about compressing DIB's using WSQ compression.  Note that OP_WSQP requires that ParmVerMinor be 2.

WSQ compression may only be used to compress 8 bits-per-pixel gray scale images.

The image data to be compressed is described in either the p.Head member of PIC_PARM or, when the F_RAW switch is set in p.FLAGS, the p.u.WSQ.Region structure is used to describe the data.

StripSize will have been set by OP_WSQP after REQ_INIT is complete.  The Get queue must be at least StripSize bytes in length, and must be a multiple of .StripSize bytes.

The output compressed image is stored in the WSQ file format by default.

An application uses PIC2List packets to supply OP_WSQP with a comment.  Therefore OP_WSQP requires that ParmVerMinor equals 2.  See the PIC2List section of Accessing Comments and Other Auxiliary Data in the  PICTools and AIMTools Programmer's Guide for more information about PIC2List packets.

If PF_Yield is set in u.WSQ.PicFlags then OP_WSQP will return a RES_YIELD response periodically during compression (during REQ_EXEC only).  This would allow an application to update compression progress reporting, for example.

U.WSQ.Quant is valid from 1 through 32. This is the desired compressed bits per pixel. The compressor will attempt to create a file whose size in bytes is = (u.WSQ.Quant * number_of_pixels)/8. The most common settings for Quant in WSQ applications are .75 and 2.25 Note that this value MUST be entered by the application setting PIC_PARM values.

U.WSQ.Black is the lowest value obtained from the scanner. Set this value to the black-point produced by the scanner. At decompression time the black point will be adjusted to 0 from this value. Note that the default value of u.WSQ.Black is 0.

U.WSQ.White is the highest value obtained from the scanner. Set this value to the white-point produced by the scanner. At decompression time the white point will be adjusted to 255 from this value. Note that this value MUST be entered by the application setting PIC_PARM values.