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APPENDIX N

CIVIL BACKGROUND CHECKS USING FLAT IMPRESSIONS DESCRIPTORS AND FIELD EDIT SPECIFICATIONS FOR TYPE-14 LOGICAL RECORDS

This section presents the descriptors and field specifications for Type-14 logical records used with flats based civil background checks. The flat-fingerprint impressions are contained in three Type-14 image records. Two of the image records contain the left and right simultaneous four fingers, and the third contains the two thumbs. Offsets to the locations of image segments containing the individual fingers are included with the image records. Most of the following definitions are taken from the ANSI Standard, Data Format for the Interchange of Fingerprint, Facial, & Scar Mark & Tattoo (SMT) Information (ANSI/NIST-ITL 1-2000).

BPX 14.012—BITS PER PIXEL. This mandatory ASCII field shall contain the number of bits used to represent a pixel. This field shall contain an entry of .8. for normal grayscale values of .0. to .255..

CGA 14.011—COMPRESSION ALGORITHM. This mandatory ASCII field shall specify the algorithm used to compress grayscale images. An entry of "NONE" in this field indicates that the data contained in this record is uncompressed. For those images that are to be compressed, this field shall contain “WSQ” the preferred method for the compression of ten-print-fingerprint images.

COM 14.020—COMMENT. This optional field may be used to insert comments or other ASCII text information with the ten-print image data.

DAT 14.999—IMAGE DATA. This field shall contain all of the data from a captured ten-print image. It shall always be assigned field number 999 and must be the last physical field in the record. For example, .14.999:. is followed by image data in a binary representation. Each pixel of uncompressed grayscale data shall be quantized to eight bits (256 gray levels) contained in a single byte. If compression is used, the pixel data shall be compressed in accordance wit h the compression technique specified in the CGA field.

FGP 14.013—FINGER POSITION. This mandatory tagged-field shall contain finger position code that matches the ten-print image. The decimal code number corresponding to the known or most probable finger position shall be taken from Table 1 and entered as a one- or two-character ASCII subfield. Table 1 also lists the maximum image area that can be transmitted for each of the fourteen possible finger positions.

Table N-1 - Finger position code & maximum size

Finger Position Finger Code Width (mm) (in) Length (mm) (in)
Unknown 0 40.6 1.6 38.1 1.5
Right thumb 1 40.6 1.6 38.1 1.5
Right index finger 2 40.6 1.6 38.1 1.5
Right middle finger 3 40.6 1.6 38.1 1.5
Right ring finger 4 40.6 1.6 38.1 1.5
Right little finger 5 40.6 1.6 38.1 1.5
Left thumb 6 40.6 1.6 38.1 1.5
Left index finger 7 40.6 1.6 38.1 1.5
Left middle finger 8 40.6 1.6 38.1 1.5
Left ring finger 9 40.6 1.6 38.1 1.5
Left little finger 10 40.6 1.6 38.1 1.5
Plain right thumb 11 25.4 1.0 50.8 2.0
Plain left thumb 12 25.4 1.0 50.8 2.0
Plain right four fingers 13 81.3 3.2 76.2 3.0
Plain left four fingers 14 81.3 3.2 76.2 3.0
Left and Right thumbs 15 81.3 3.2 76.2 3.0

 

HLL 14.006—HORIZONTAL LINE LENGTH. This mandatory ASCII field shall contain the number of pixels contained on a single horizontal line of the transmitted image.

HPS 14.009—HORIZONTAL PIXEL SCALE. This mandatory ASCII field shall specify the integer pixel density used in the horizontal direction providing the SLC contains a "1" or a "2." Otherwise, it indicates the horizontal component of the pixel aspect ratio.

IDC 14.002—IMAGE DESIGNATION CHARACTER. This mandatory ASCII field shall be used to identify the ten-print-fingerprint image contained in the record. This IDC shall match the IDC found in the file content (CNT) field of the Type-1 record.

IMP 14.003—IMPRESSION TYPE. This mandatory one-byte ASCII field shall indicate the manner by which the ten-print image information was obtained. The appropriate code selected from Table 2 shall be entered in this field.

IQM 14.022—IMAGE QUALITY METRIC. This mandatory ASCII field shall contain the image quality scores for the individual fingers. Each finger score is defined by the FINGER NUMBER and the QUALITY SCORE separated by the separator. Individual finger quality definitions are separated by the separator.

Table N-2 - Finger impression type

Description Code
Live-scan plain 0
Live-scan rolled 1
Nonlive-scan plain 2
Nonlive-scan rolled 3
Latent impression 4
Latent tracing 5
Latent photo 6
Latent lift 7

LEN 14.001—LOGICAL RECORD LENGTH. This mandatory ASCII field shall contain the total count of the number of bytes in the Type-14 logical record. Field 14.001 shall specify the length of the record, including every character of every field contained in the record, and the information separators.

SEG 14.021—FINGER SEGMENT POSITION(s). This mandatory ASCII field shall contain offsets to the locations of image segments containing the ind ividual fingers within the image. The offsets are relative to the origin, (0,0), which is in the upper left corner of the image. The horizontal offsets (X) are the pixel counts to the right, and the vertical offsets (Y) are the pixel counts down. A finger segment is defined by the FINGER NUMBER, the X coordinates (LEFT, RIGHT) and the Y coordinates (TOP, BOTTOM), of its bounding box. The five information items within a finger segment definition are separated by the separator. Individual finger segment definitions are separated by the separator.

SLC 14.008—SCALE UNITS. This mandatory ASCII field shall specify the units used to describe the image sampling frequency (pixel density). A "1" in this field indicates pixels per inch, or a 2" indicates pixels per centimeter. A "0" in this field indicates no scale is given. For this case, the quotient of HPS/VPS gives the pixel aspect ratio.

SRC 14.004—SOURCE AGENCY. This mandatory ASCII field shall contain the identification of the administration or organization that originally captured the ten-print image contained in the record. Normally, the ORI of the agency that captured the image will be contained in this field. The SRC may contain up to 20 identifying characters. The data content of this field shall be defined by the user and be in accordance with the receiving agency.

TCD 14.005—TEN-PRINT CAPTURE DATA. This mandatory ASCII field shall contain the date that the ten-print image was captured. The date shall appear as eight digits in the format CCYYMMDD. The CCYY characters shall represent the year the image was captured; the MM characters shall be the tens and units values of the month; and the DD characters shall be the tens and units values of the day in the month. For example, the entry 20000229 represents February 29, 2000. The complete date must be a legitimate date.

VLL 14.007—VERTICAL LINE LENGTH. This mandatory ASCII field shall contain the number of horizontal lines contained in the transmitted image.

VPS 14.010—VERTICAL PIXEL SCALE. This mandatory ASCII field shall specify the integer pixel density used in the vertical direction providing the SLC contains a "1" or a "2." Otherwise, it indicates the vertical component of the pixel aspect ratio.

 

TABLE N-3 FIELD LIST FOR FLATS CIVIL CHECK TYPE-14 RECORD

Identifier Condition Field Number Field Name Character Type Field Size Per Occurrence Min Field Size Per Occurrence Max Occurrences Min Occurrences Max Maximum Number of Bytes Example Data
LEN M 14.001 LOGICAL REC LENGTH N 4 8 1 1 15 14.001:40164<GS>
IDC M 14.002 IMAGE DESIGNATION CHAR N 2 5 1 1 12 14.002:01<GS>
IMP M 14003 IMPRESSION TYPE A 2 2 1 1 9 14.003:0<GS>
SRC M 14.004 SOURCE AGENCY/ORI AN 10 21 1 1 28 14.004:CA0000001<GS>
TCD M 15.005 TEN-PRINT CAPTURE DATE N 9 9 1 1 16 14:005:20040227<GS>
HLL M 14.006 HORIZONTAL LINE LENGTH N 4 5 1 1 12 14:006:1600<GS>
VLL M 14.007 VERTICAL LINE LENGTH N 4 5 1 1 12 14:007:1450<GS>
SLC M 14.008 SCALE UNITS N 2 2 1 1 9 14.008:1<GS>
HPS M 14.009 HORIZONTAL PIXEL SCALE N 2 5 1 1 12 14:009:500<GS>
VPS M 14.010 VERTICAL PIXEL SCALE N 2 5 1 1 12 14:010:500<GS>
CGA M 14.011 COMPRESSION ALGORITHM A 5 7 1 1 14 14:011:1<GS>
BPX M 14.012 BITS PER PIXEL N 2 3 1 1 10 14:012:8<GS>
FGP M 14.013 FINGER POSITION CODE N 2 2 1 6 25 14.013:13<GS>
SEG M 14.021 SEGMENT POSITION   2 4 99 14.021:10<US>3<US>352<US>725<US>1265<US><RS>
M FINGER NUMBER N 1 2 1 1 99 9<US>375<US>750<US>175<US>765<RS>
M LEFT N 1 4 1 1 8<US>800<US>1150<US>5<US>581<RS>
M RIGHT N 1 4 1 1 7<US>1200<US>1598<US>274<US>801 <GS>
M TOP N 1 4 1 1
M BOTTOM N 1 4 1 1
IQM M 14.022 IMAGE QUALITY METRIC 2 4 58 14.022:10<US>6<US>9<US>4<RS>8<US>3<RS>7<US>3 <GS>
M FINGER NUMBER N 1 2 1 1
M QUALITY SCORE N 1 2 1 1
DAT M 14.999 IMAGE DATA B 2 1 1 14.999:<IMAGE DATA COMPRESSED@15:1><FS>< IMAGE DATA COMPRESSED@ 15:1 >

 

 

 

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