APPENDIX F
IAFIS IMAGE QUALITY SPECIFICATIONS

1.0 SCOPE AND PURPOSE

These specifications apply to: (1) systems which scan and capture fingerprints⁴ in digital, softcopy form, including hardcopy scanners such as ten-print card scanners, and live scan devices, altogether called ‘fingerprint scanners’; and (2) systems utilizing a printer to print digital fingerprint images to hardcopy, called ‘fingerprint printers’. These specifications provide criteria for insuring the image quality of fingerprint scanners and printers that input fingerprint images to, or generate fingerprint images from within, the Integrated Automated Fingerprint Identification System (IAFIS).

Digital softcopy images obtained from fingerprint scanners must have sufficient quality to allow the following functions to be performed: (l) conclusive fingerprint comparisons (identification or non-identification decision); (2) fingerprint classification; (3) automatic feature detection; and (4) overall Automated Fingerprint Identification System (AFIS) search reliability. The fingerprint comparison process requires a high fidelity image. Finer detail, such as pores and incipient ridges, are needed because they can play an important role in the comparison.

The fingerprint examiners in the IAFIS environment will depend upon softcopy displayed images of scanned fingerprints to make comparisons, but will also need to accept and utilize hardcopy images in certain instances. For example, some contributors may print cards from live scan or card scan systems for submission to the FBI. These hardcopy prints will be obtained from printers that include printing algorithms optimized for fingerprints. The printer’s principle function is to produce life-size prints of digital fingerprints that have met IAFIS format requirements, and provide sufficient print quality to support fingerprint comparisons, i.e., support identification or non-identification decisions.

The image quality requirements covered in the following sections 2 and 3 for fingerprint scanners, section 4 for fingerprint printers, and section 5 for Fast-Track requirements, have associated test procedures that are described in detail in [Test Procedures].

These test procedures will be used by the FBI principally for certification of fingerprint systems; they may also be used in acceptance testing, and in performance capability demonstrations, as an indication of capability to perform. Equipment shall be tested to meet the requirements in normal operating modes, e.g., scanners shall not be tested at slower than normal operating speeds in an attempt to meet geometric accuracy specifications. A vendor may recommend alternate testing methods if the test procedures given in this Appendix are not applicable or cannot be applied to the particular system under test.

The fingerprint scanner must be capable of producing images that exhibit good geometric fidelity, sharpness, detail rendition, gray-level uniformity, and gray-scale dynamic range, with low noise characteristics. The images must be true representations of the input fingerprints, without creating any significant artifacts, anomalies, false detail, or cosmetic image restoration effects.

The scanner’s final output resolution, in both sensor detector row and column directions, shall be in the range: (R–0.01R) to (R+0.01R) and shall be gray-level quantized to 8 bits per pixel (256 gray-levels). The magnitude of “R” is either 500 pixels per inch (ppi) or 1000 ppi; a scanner may be certified at either one, or both, of these resolution levels. The scanner’s true optical resolution shall be greater than or equal to R.

A scanner intended to scan standard 8.0 by 8.0 inch ten-print cards, e.g., applicant fingerprint card type FD-258 or FD-249, shall be capable of capturing an area of at least 5.0 by 8.0 inches, which captures all 14 printblocks, either each printblock as a separate image, or all printblocks together as a single image. Table 2-1 gives the preferred capture sizes, applicable to both card scan and live scan systems. Scanner capture dimensions should never be less than 90% of those given in Table 2-1, with the exception that when scanning fingerprint cards, the card form dimensions take precedence. Maximum capture sizes may be found in [EFTS] and [ANSI/NIST].

⁴ The term ‘fingerprint’ in this Appendix may also include palmprint, whole hand print, or a print from other parts of the human body.

Table F-1. Preferred Capture Sizes

* Live scanner must be capable of capturing at least 80% of full roll arc length, where full roll arc length is defined as arc length from nail edge-to-nail edge.

2.1 Linearity

Requirement: When measuring a stepped series of uniform target reflectance patches (e.g., step tablet) that substantially cover the scanner’s gray range, the average value of each patch shall be within 7.65 gray-levels of a linear, least squares regression line fitted between targe t reflectance patch values (independent variable) and scanner output gray-levels (dependent variable).

Background: All targets used in IQS compliance verification are expected to be scanned with the scanner operating in a linear input/output mode. Linearity enables valid comparisons of test measurements with requirements, e.g., a system’s spatial frequency response in terms of Modulation Transfer Function is, strictly speaking, a linear systems concept. Linearity also facilitates comparisons between different scanners through the ‘common ground’ concept. In atypical cases, a small amount of smooth, monotonic nonlinearity may be acceptable for the test target scans, i.e., when it is substantially impractical and unrepresentative of operational use, to force linearity on the scanner under test (e.g., some livescan devices). Linearity is not a requirement for the operational or test fingerprint scans, which allows for processing flexibility to overcome inadequate tonal characteristics of fingerprint samp les.

2.2 Geometric Accuracy

Requirement (across-bar)

When scanning a multiple, parallel bar target, in both vertical bar and horizontal bar orientations, the absolute value of the difference between the actual distance across parallel target bars, and the corresponding distance measured in the image, shall not exceed the following values, for at least 99.0% of the tested cases in each printblock measurement area and in each of the two orthogonal directions.

for 500 ppi scanner: D = 0.0007, for 0.00 < X = 0.07

D = 0.01X, for 0.07 = X = 1.50

for 1000 ppi scanner: D = 0.0005, for 0.00 < X = 0.07

D= 0.0071X, for 0.07 = X = 1.5

where: D = |Y-X| X = actual target distance Y = measured image distance D, X, Y are in inches

Requirement (along-bar): When scanning a multiple, parallel bar target, in both vertical bar and horizontal bar orientations, the maximum difference in the horizontal or vertical direction, respectively, between the locations of any two points within a 1.5 inch segment of a given bar image, shall not exceed 0.016 inches for at least 99.0% of the tested cases in each printblock measurement area and in each of the two orthogonal directions.

Background: In this section 2.2, the phrase: multiple, parallel bar target refers to a Ronchi target, which consists of an equal-width bar and space square wave pattern at 1.0 cy/mm, with high contrast ratio and fine edge definition. This target is also used to verify compliance with the scanner resolution requirement given in section 2.0.

Across-bar geometric accuracy is measured across the imaged Ronchi target bars that substantially cover the total image capture area. The 500 ppi requirement corresponds to a positional accuracy of ± 1.0% for distances between 0.07 and 1.5 inches, and a constant ± 0.0007 inches (1/3 pixel) for distances less than or equal to 0.07 inches. The 1000 ppi requirement corresponds to a positional accuracy of ± 0.71% for distances between 0.07 and 1.5 inches, and a constant ± 0.0005 inches (1/2 pixel) for distances less than or equal to 0.07 inches.

This measurement procedure is also used to verify the ppi resolution requirement given in section 2.0.

Along-bar geometric accuracy is measured along the length of an individua l Ronchi target bar in the image. For a given horizontal bar, for example, the maximum difference between bar center locations (in vertical direction), determined from bar locations measured at multiple points along a 1.5” bar segment length, is compared to the maximum allowable difference requirement (analogously for vertical bar). This requirement is to ensure that pincushion or barrel distortion over the primary area of interest, i.e., a single fingerprint, is not too large.

Requirements: The spatial frequency response shall be measured using a continuous tone sine wave target, denoted as Modulation Transfer Function (MTF) measurement, unless the scanner cannot obtain adequate tonal response from this target, in which case a bi-tonal bar target shall be used to measure the spatial frequency response, denoted as Contrast Transfer Function (CTF) measurement. When measuring the sine wave MTF, it shall meet or exceed the minimum modulation values given in Table 2-1, in both the detector row and detector column directions, and over any region of the scanner's field of view. When measuring the bar CTF, it shall meet or exceed the minimum modulation values defined by equation 2-1 or equation 2-2 (whichever applies), in both the detector row and detector column directions, and over any region of the scanner's field of view. CTF values computed from equations 2-1 and 2-2 for nominal test frequencies are given in Table 2-2.

None of the MTF or CTF modulation values measured at specification spatial frequencies shall exceed 1.05.

The output sine wave image or bar target image shall not exhibit any significant amount of aliasing.

Table F-2. MTF Requirement Using Sine Wave Target

Note: Testing at 7 and 9 cy/mm is not a requirement if these frequency patterns are absent from the sine wave target.

Table F-3. CTF Requirement Using Bar Target (Nominal Test Frequencies)

It is not required that the bar target contain the exact frequencies listed in Table 2-2; however, the target does need to cover the listed frequency range, and contain bar patterns close to each of the listed frequencies. The following equations are used to obtain the specification CTF modulation values when using bar targets that contain frequencies not listed in Table 2-2.

500 ppi scanner, for f = 1.0 to 10.0 cy/mm: CTF = 3.04105E -04 * f ² -7.99095E -02 * f + 1.02774 (eq.2 -1)

1000 ppi scanner, for f = 1.0 to 20.0 cy/mm: CTF = -1.85487E -05 * f ³ + 1.41666E -03 * f ² -5.73701E -02 * f +1.01341 (eq.2 -2)

Background: For MTF assessment, the single, representative sine wave modulation in each imaged sine wave frequency pattern is determined from the sample modulation values collected from within that pattern. The sample modulation values are computed from the maximum and minimum levels corresponding to the 'peak' and adjacent 'valley' in each sine wave period. For a sine wave image, these maximum and minimum levels represent the image gray-levels that have been locally averaged in a direction perpendicular to the sinusoidal variation, and then mapped through a calibration curve into target reflectance space. Sample image modulation in target reflectance space is then defined as:

modulation = (maximum -minimum) / (maximum + minimum)

The calibration curve is the curve of best fit between the image gray-levels of the density patches in the sine wave target and the corresponding target reflectance values. [It is assumed that sine wave target modulations and target density patch values are supplied by the target manufacturer.] The scanner MTF at each frequency is then defined as:

MTF = peak image modulation / target modulation

For CTF assessment, the modulations are determined directly in image space, normalized by the image modulation at zero frequency, instead of using a calibration curve. The scanner CTF at each frequency is then defined as:

CTF = peak image modulation / (zero frequency image modulation)

The bar target must contain at least 10 parallel bars at each of the higher spatial frequencies (~50% Nyquist to Nyquist frequency), which helps to ensure capture of optimum scanner - target phasing and aids investigation of potential aliasing. The bar target must also contain a very low frequency component, i.e., a large square, bar, or series of bars whose effective frequency is less than 2.5 % of the scanner’s final output resolution. This low frequency component is used in normalizing the CTF, it must have the same density (on the target) as the higher frequency target bars.

The upper limit of 1.05 modulation is to discourage image processing that produces excessive edge sharpening, which can add false detail to an image.

Aliasing on sine wave images or bar images may be investigated by quantitative analysis and from visual observation of the softcopy-displayed image.

2.4 Signal-to-Noise Ratio

Requirement: The white signal-to-noise ratio and black signal-to-noise ratio shall each be greater than or equal to 125.0, in at least 97.0% of respective cases within each printblock measur ement area.

Background: The signal is defined as the difference between the average output gray-levels obtained from scans of a uniform low reflectance and a uniform high reflectance target, measuring the average values over independent 0.25 by 0.25 inch areas within each printblock area. The noise is defined as the standard deviation of the gray-levels in each of these quarter-inch measurement areas. Therefore, for each high reflectance, low reflectance image pair there are two SNR values, one using the high reflectance standard deviation and one using the low reflectance standard deviation. In order to obtain a true measure of the standard deviation, the scanner is set up such that the white average gray-level is several gray-levels below the system’s highest obtainable gray-level and the black average gray-level is several gray-levels above the system’s lowest obtainable gray-level.

2.5 Gray-level Uniformity

Requirement - adjacent row, column uniformity: At least 99.0% of the average gray-levels between every two adjacent quarter-inch long rows and 99.0% between every two adjacent quarter-inch long columns, within each imaged printblock area, shall not differ by more than 1.0 gray-levels when scanning a uniform low reflectance target, and shall not differ by more than 2.0 gray-levels when scanning a uniform high reflectance target.

Requirement - pixel to pixel uniformity: For at least 99.9% of all pixels within every independent 0.25 by 0.25 inch area located within each imaged printblock area, no individual pixel's gray-level shall vary from the average by more than 22.0 gray-levels, when scanning a uniform high reflectance target, and shall not vary from the average by more than 8.0 gray-levels, when scanning a uniform low reflectance target.

Requirement - small area uniformity: For every two independent 0.25 by 0.25 inch areas located within each imaged printblock area, the average gray-levels of the two areas shall not differ by more than 12.0 gray-levels when scanning a uniform high reflectance target, and shall not differ by more than 3.0 gray-levels when scanning a uniform low reflectance target.

Background: Measurements are made over multiple, independent test areas, on a printblock by printblock basis. [For a live scanner, the entire capture area is normally considered a single printblock area]. In order to obtain a true measure of the standard deviation, the scanner is set up such that the white average gray-level is several gray-levels below the system’s highest obtainable gray-leve l and the black average gray-level is several gray-levels above the system’s lowest obtainable gray-level.

2.6 Fingerprint Image Quality

The scanner shall provide high quality fingerprint images; the quality will be assessed with respect to the following requirements.

Requirement -Fingerprint Gray Range: At least 80.0 % of the captured individual fingerprint images shall have a gray-scale dynamic range of at least 200 gray-levels, and at least 99.0 % shall have a dynamic range of at least 128 gray-leve ls.

Background: Card and live scan systems at a booking station have some control over dynamic range, on a subject-by-subject or card-by-card basis, e.g., by rolling an inked finger properly, or by adjusting gain on a livescanner. However, with central site or file conversion systems, where a variety of card types and image qualities are encountered in rapid succession, automated adaptive processing may be necessary. The 8 bits per pixel quantization of the gray-scale values for very low contrast fingerprints needs to more optimally represent the reduced gray-scale range of such fingerprints, but without significant saturation. The intent is to avoid excessively low contrast images without adding false detail.

Dynamic range is computed in terms of number of gray-levels present that have signal content, measuring within the fingerprint area and substantially excluding white background and card format lines, boxes, and text.

For card scanners, compliance with these dynamic range requirements will be verified using a statistically stratified sample set of fingerprint cards assembled by the FBI. The test fingerprint card set may include cards with difficult to handle properties, e.g., tears, holes, staples, glued-on photos, or lamination, for testing card scanners which have automatic document feeder mechanisms. For live scanners, compliance will be verified with sets of livescans produced by the vendor.

Requirement - Fingerprint Artifacts and Anomalies:

Artifacts or anomalies detected on the fingerprint images, which are due to the scanner or image processing, shall not significantly adversely impact support to the functions of conclusive fingerprint comparisons (identification or non-identification decision), fingerprint classification, automatic feature detection, or overall Automated Fingerprint Identification System (AFIS) search reliability.

Background: The fingerprint images will be examined to determine the presence of artifacts or anomalies that are due to the scanner or image processing; assessment may include measurements to quantify their degree of severity and significance. Image artifacts or anomalies such as the following non-inclusive list may be investigated:

• jitter noise effects
• sharp truncations in average gray-level between adjacent printblocks
• gaps in the gray-level histograms, i.e., zero pixels in intermediate gray-levels, or clipping to
• less than 256 possible gray-levels
• imaging detector butt joints
• noise streaks
• card bleed-through
• gray level saturation

Requirement - Fingerprint Sharpness & Detail Rendition: The sharpness and detail rendition of the fingerprint images, due to the scanner or image processing, shall be high enough to support the fingerprint functions stated in section 1, paragraph 2.

Background: Fingerprint sharpness and detail rendition, which is due to the scanner or image processing, may be investigated by employing suitable, objective image quality metrics, as well as by visual observation of the softcopy-displayed image.

3.0 IDENTIFICATION FLATS

Traditional fingerprint sets contain both rolled and plain fingerprint images. The rolled impressions support the search processing and identification functions and the plain impressions are used primarily for sequence verification. Fingerprinting systems designed for “Identification Flats” civilian background checks capture a single set of plain impressions. This single set of plain impressions must support finger sequence verification, search processing, and identification.

Image quality has historically been a challenge for civil background checks. Some programs require a large number of relatively low volume capture sites, which makes training difficult. A key goal for identification flats scanners is to reduce the need for training, so that inexperienced users consistently capture quality fingerprint images.

The Identification Flats scanner shall meet all of the requirements stated in Section 2 of this Appendix F as well as the following requirements.

Requirement – Capture Protocol: The system shall provide a simple capture protocol.

Background: A simple capture protocol supports the inexperienced user’s ability to more consistently capture high quality fingerprints. Identification Flats collection systems will be evaluated for their ability to produce a very small rate of failure to enroll in an operational setting. Systems with a minimum capture area of 3.2 inches (width) by 2.9 inches (height), which can capture 4 fingers simultaneously in an upright position, will be considered in compliance with the simple capture protocol requirement. Other capture approaches will require specific testing and documentation.

Requirement – Verifiable Finger Sequence Data: The method of capturing the fingers shall result in very low probability of error in the finger numbers.

Background: The fingerprinting system’s capture protocol will be evaluated for its ability to capture verifiable finger sequence data. Systems with a minimum capture area of 3.2 inches (width) by 2.9 inches (height), which capture 4 fingers simultaneously in an upright position, will be considered in compliance with the finger sequence requirements. Other capture approaches will require specific testing and documentation.

4.0 FINGERPRINT PRINTER

The fingerprint printer, consisting of a printer and specialized print algorithm, must be capable of producing hardcopy images which exhibit good geometric fidelity, sharpness, detail rendition, gray-level uniformity, and gray-scale dynamic range characteristics, with low noise, no significant creation of false detail, and with the capability to support magnified viewing of the print without breakup of the virtual fingerprint image presented to the eye. This printer is expected to provide high throughput, good repeatability, good print permanency characteristics, and low cost per copy. A typical fingerprint printer is a gray-scale laser printer⁵ with 1200 black/white dots per inch resolution, combined with a printing algorithm that typically includes image contrast and printer gamma/highlight/lowlight adjustments, image rescaling, and an error diffusion model with randomized dot dither printing applied to the rescaled image.

The print system’s principle function is to produce life-size prints of digital fingerprints that have met IAFIS format requirements, as specified in [EFTS] and [ANSI/NIST], and to provide sufficient print quality to support fingerprint comparisons, i.e., support identification or non-identification decisions. The printer should also have the capability to print gray-scale mugshots and property/evidence photos (not necessarily using a fingerprint printing algorithm), as well as print black & white documents containing text and graphics, onto 8.5 x 11.0 inch paper.

A required printer resolution is 500 ppi, which produces the required life-size print when the input digital fingerprint is 500 ppi, or when a 1000 ppi digital fingerprint is down-scaled to 500 ppi prior to printing. In both cases all other 500 ppi printer requirements must also be met.

Verification of the specific performance requirements in this section 4 of Appendix F is accomplished by evaluating the printer's output print of an FBI-designated test set of digitized fingerprints and FBI-designated digital test target. Requirements compliance verification is performed by a combination of visual assessments of the test prints (aided by visual instruments) and computer-aided assessments of scanned digital images of the test prints. With respect to those requirements that depend on assessments of print scans for compliance verification, the scan resolution is expected to be twice the required gray-scale print resolution, e.g., a print with 500 ppi resolution is scanned at 1000 ppi, and the scanner is expected to be setup in a calibrated linear input/output, grayscale reflectance capture mode.

4.1 Spatial Frequency Response

Requirement: The printer shall provide sufficient spatial frequency response to support visually resolving the required printer resolution, in orthogonal directions on the print.

⁵ In this Appendix, “laser printer” refers to a type of printer in which a laser beam ‘draws’ an electrostatic image of an input signal onto a drum. Toner (typically dry powder) is then transferred to the charged areas of the drum, which then transfers the toner onto paper, where it is fused by heat, creating a black/white/gray image.

Background: Resolution verification is performed by printing high contrast digital bar targets and visually inspecting the print under magnification. [When employing a laser printer with a fingerprint printing algorithm, it is recognized and accepted that the effective resolution may vary in complex image areas such as a fingerprint.]

The resolution limit is a single point on the spatial frequency response curve; the entire curve may be measured by scanning the print of an appropriate target, performing appropriate computer-aided assessment on the scan, and comparing results to a minimally acceptable spatial frequency response curve.

4.2 Gray-levels

Requirement: At least 16 gray-levels shall be visually distinguishable on the print.

Background: Visual observation of the print of a digital target containing a step tablet is used to verify the 16 gray-level requirement. A higher number of gray-levels is expected to be distinguishable by appropriate computer-aided assessment of the scanned image of the print.

4.3 Dynamic Range

Requirement: The printer shall have the capability to print an input digital image gray range of at least 150, excluding print black saturation and print white saturation.

Background: The print of a digital step tablet is scanned, each pixel’s output gray-level value is converted to the corresponding print reflectance value, and the average print reflectance value within each step is computed. A plot of step average print reflectance versus input digital step tablet gray level must result in a gray range of at least 150, excluding anysaturation on the low end (print black reflectance) and high end (print white reflectance). [The scanner output gray-level to print reflectance conversion is established by gene rating the scanner’s input/output curve using a calibrated step tablet.]

4.4 Geometric Accuracy and Print Scale

Requirement (across-bar): When printing a digital bar target containing multiple, parallel bars, then the absolute value of the difference between the measured distance across parallel bars on the print and the correct distance on the print, shall not exceed the following values, for at least 97% of the tested cases in each direction (vertical and horizontal):

D = 0.001, for 0.00 < X = 0.07

D = 0.015X, for 0.07 < X = 1.50

where: D = |Y-X| X = correct distance = digital target pixels / required print resolution Y = measured distance on print D, X, Y are in inches

Requirement (along-line): Straight target lines printed parallel to, or at a 45 degree angle to, the paper or card edges, shall be straight on the print, with no significant waviness, bow, or ‘staircasing’.

Background: The across-bar requirement corresponds to a positional accuracy of ± 1.5% for distances greater than 0.07 inches and less than or equal to 1.5 inches, and a constant ± 0.001 inches for distances less than or equal to 0.07 inches. With a 500 ppi required print resolution, a digital bar target with a period of 18 pixels is used, which corresponds to a bar frequency of 500 / (25.4*18) cy/mm on the print, when printed life-size. The measured distance on the print can be obtained by scanning the print and applying computer-assisted assessment on the resulting digital image. The requirement takes into account the geometric errors inherent in a good quality scanner. For life-size printing, the print scale error is measured over a distance in the 0.07 to 1.50 inch range. Print scale error is equal to: (correct distance -measured distance) / correct distance. For life-size printing at 500 ppi, a 1.5% allowable error in distance, measured in inches, is equivalent to an allowable print ppi error equal to ± 7.5 ppi.

The along-line requirement can be assessed visually, aided, e.g., by a straight-edge and magnifying lens.

4.5 Noise

Requirement: For a required printer resolution of 500 ppi, the noise magnitude shall be less than 0.120 at each average print reflectance level, when noise magnitude is defined as the standard deviation of print reflectance values within an area on the print corresponding to a constant gray level on the input digital target. [Print reflectance measured in fractional units: 0.0 to 1.0 range.]

Background: A digital step tablet is printed, the print is scanned at 1000 ppi, each pixel’s output gray-level value is converted to the corresponding print reflectance value, and the standard deviation of print reflectance values within each step is computed. The scanner output gray-level to print reflectance conversion is established by generating the scanner’s input/output curve using a calibrated step tablet.

4.6 Print Polarity and Color

Requirement: The printed fingerprints shall appear as dark gray-to-black ridges on a light gray-to-white background.

4.7 Print Permanence

Requirement: The printed fingerprints shall not smear or smudge with normal handling.

4.8 Print Stability

Requirement: Both the fingerprints and the card stock or paper on which they are printed shall retain their visually neutral (black, white, gray) color over time.

4.9 Hazardous Materials

Requirement: The prints shall not produce any health hazard as a result of handling. They shall not produce any noxious, annoying, or unpleasant odors when accumulated in large numbers and handled in areas having limited ventilation.

Background: Requirements 4.7 (print permanence), 4.8 (print stability), and 4.9 (hazardous materials) are met by standard laser printers.

4.10 FINGERPRINT PRINTS

4.10.1 Print Types Requirements

The printer shall have the capability to print a set of individual livescans or previously scanned, individual inked fingerprints, life-size and in their correct printblock locations, onto a standard ten-print fingerprint card (e.g., fingerprint card type FD-258), or print onto blank 8.0 by 8.0 inch card stock, or print onto blank 8.5 x 11.0 inch plain paper. In the case of printing fingerprints onto blank card stock or blank paper, the printer shall also print the printblock boundary lines and labeling that normally appears on a standard ten-print card.

The printer shall have the capability to print a previously scanned ten-print card, in its entirety and life-size, onto blank 8.0 x 8.0 inch card stock, or onto blank 8.5 by 11.0 inch plain paper.

The printer shall have the capability to print a single fingerprint, magnified up to 5 times beyond life-size, onto 8.5 by 11.0 inch plain paper.

When printing in ten-print card format onto ten-print card stock, blank card stock, or plain paper, the printer shall also have the capability to print labels, bar chart, step tablet, and finger condition codes, all on the same print with the fingerprints. Figure 4-1 illustrates the printing of this auxiliary information; following sections 4.10.2 through 4.10.5 give the detailed requirements.

4.10.2 Labels

Requirement: When printing fingerprints in ten-print card format, the printing process shall have the capability to print a character string of scanner information within the left four finger plain impression printblock, and a character string of printer information within the right four finger plain impression printblock. Each character string shall be printed along the top inside edge of the respective printblock, in a type font and size that is large enough for human readability without the aid of a magnifier, and small enough so as not to unduly impinge on fingerprint structure.

The scanner information string shall include the scanner make, model number, and serial number, if available, and/or similar information on the scanner system. The printer information string shall include the printer make, model number, and serial number, if available, shall include similar information on the fingerprint printing algorithm, if available, and shall include the date and time of printing.

The scanner and printer character strings shall be printed without a background, border, or any other type of added surround.

Background: Information for the scanner string can typically be obtained from the EFTS Type-2 Record Field identified as "IMA 2.067 - Image Capture Equipment", which includes scanner system make, model number, and serial number.

A printer is certified as a combination of a specific brand/model printer and fingerprint printing algorithm; the latter may also have a name or version designation.

Character string printing: a solid background (e.g., white) to the character string is unacceptable because it would unnecessarily obliterate some parts of fingerprints on some images. Individual characters with no background that overprint the fingerprint, would obliterate a much smaller proportion of the fingerprint and are acceptable. Printing the character strings in an open space created by off-setting printblocks 6-10 from printblocks 11-14 is unacceptable because it changes the dimensions of the standard ten-print card format, and it cannot adequately accommodate fingerprints that stray across printblock boundaries.

Proper text size typically would correspond to a height of a numeral or upper case letter being in the range : 0.067 inches to 0.095 inches.

4.10.3 Bar Chart

Requirement: When printing fingerprints in ten-print card format, the printing process shall have the capability to print a bar chart, consisting of equally-spaced horizontal black bars and vertical black bars printed at the required printer resolution.

The Bar Chart shall be positioned at the top edge within the right thumb plain impression printblock and shall have a maximum width of 0.8 inches and a maximum height of 0.125 inches. The Bar Chart shall contain at least 10 parallel bars in each direction, vertical and horizontal, with a bar length of at least 0.0625 inches (not necessarily the same number of bars, or same bar length, in the two directions).

An optional, uniform mid-grey level patch may be included between the horizontal and vertical bar components.

The bar chart shall be printed without a background, border, or any other type of added surround.

Background: For a 500 ppi printer requirement the limiting frequency is 250 cycles per inch, which implies that 250 black bars per inch are printed, where the 0.002 inch width of an individual bar is equal to the width of the white space between two bars.

If a mid-gray patch between the vertical and horizontal bar patterns appears to have the same overall gray-level on the print as the two bar patterns, then this may indicate that the printer gamma/highlight/lowlight settings are optimum and/or that the printer toner supply was adequate for printing.

4.10.4 Step Tablet

Requirement: When printing fingerprints in ten-print card format, the printing process shall have the capability to print a step tablet, consisting of two adjacent horizontal bands, each band having 16 gray-levels. The top band shall progressively darken from left to right and the bottom band shall progressively darken from right to left. The 16 digital input gray-levels corresponding to one band shall be identically the same as for the other band, and both bands shall substantially cover the total gray-level range. This step tablet shall be positioned at the top edge within the left thumb plain impression printblock and shall have a total width between 0.5 inches and 0.8 inches, and a total height between 0.0625 inches and 0.125 inches.

The step tablet shall be printed without a background, border, or any other type of surround.

Background: If the top band and bottom band appear ‘balanced’ on the print, i.e., the same mid-gray-level appears in the middle of both the top and bottom bands, then this may indicate that the printer gamma/highlight/lowlight settings are optimum.

4.10.5 Finger Condition Codes

Requirement: When printing fingerprints in ten-print card format, the printing process shall have the capability to notate the presence of an abnormal finger condition in the appropriate printed fingerprint block, for those cases where the EFTS Type-2 Record Field identified as "AMP" (amputated or bandaged) is available, and/or for those cases where similar information is available from other sources, such as a state system (possibly with other notation codes).

4.10.6 Fingerprint Quality

Requirement: The printer shall produce sufficient print quality to allow usable viewing of life-size fingerprint prints under magnification, in order to support fingerprint comparisons, i.e., support identification or non-identification decisions. The print image shall maintain its sharpness and detail rendition structure up to at least 4X magnification, to the extent that ridges, and ridge joints, bifurcations, and terminations that exist in the input digital image to the printer, can be substantially discerned by the human observer on the output print, without being 'lost in the noise.' In addition, the printing process shall not create significant false detail, e.g., shall not create ridges where none existed in the input digital image.

Background: Assessment of the requirement is performed by visual inspection of the print augmented by appropriate quantitative analysis of the scanned print.

Figure 4-1 Auxiliary Information Printed in Ten-Print Card Format Print (Example Text)

5. FAST-TRACK CERTIFICATION

First, to review, full certification testing is required when:

• An uncertified livescan device is presented together with suitable SW, such that the combination prospectively meets all IQS requirements.
• A hardcopy scanner or printer (typically a COTS product) is presented together with suitable SW, such that the combination prospectively meets all IQS requirements. [The specific SW may be sold separately from the COTS HW but only the specific HW/SW combination is certified.]
• Substantive modifications are made to an already-certified device. For example, the sensor or optics is changed, the capture area is expanded, the signal processing is substantively changed, or a 500 ppi certified device is extended for operation at 1000 ppi.

Fast Track certification testing is sufficient when:

• A vendor adds ‘value’ to an already-certified device, for example, by integrating additional SW and/or HW, and repackaging the combination to create a VAR label system. However, if there is a reasonable expectation that the added SW, HW, or repackaging will affect the image quality performance of the original certified device, then full certification testing would be required.
• A vendor makes relatively minor modifications to a previously certified device. For example, a membrane is added to (or deleted from) a certified livescanner, an automatic document feeder is added to a certified manual-feed cardscanner, or a 1000 ppi certified scanner is operated at 500 ppi, using the same optics, sensor, and illumination.

Table 5-1 presents the test data requirements for some common Fast Track certification scenarios; for test requirements for other scenarios contact the FBI. In addition to the test data, the vendor seeking Fast Track certification must provide a written statement to the FBI (letter or email) which affirms that the previously certified fingerprint device has not been changed, with respect to device functions, hardware, firmware, or software that could reasonably be expected to affect image quality performance*. Specific to a scanner, the optics and optical layout, sensor, illumination, image capture electronics and signal processing have not been changed and the maximum capture area has not been increased.

* Except for inherent image quality changes in specific situations, e.g., when recertifying a 1000 ppi scanner at 500 ppi.

Table F-5. Fast Track Certification Procedures (Common Scenarios)

No certification testing is necessary when:

• The original recipient of a certification wishes to change the model name and there are no other changes to the certified product.
• The original recipient of a certification wishes to repackage the device, if there is a reasonable expectation that the repackaging will not affect the image quality performance of the device. All device HW/SW components that may affect image quality performance must remain the same as they were when originally certified. For example, repackaging a device into a ruggedized cabinet, or repackaging a floor-standing device as a desktop device by separating-out the host computer would not necessarily require further testing, but changing the optical path or optical train of elements to accommodate the repackaging would normally require retesting.
• A reseller of a certified device wishes to sell the device under it’s own label, or under the original label. The certified device must remain intact, unmodified, and as a stand-alone product with no added HW/SW. If relabeled by reseller, the certification is only valid when that label does in fact contain the originally certified device, i.e., no blanket certification for rebrands.
• An end user receives a certified device to be used ‘as is’, without modification (an end-user does not need its own certification).

Definition of Terms:

HW -HardWare, which may include firmware SW -SoftWare, which may include firmware COTS - Commercial-Off-The-Shelf product Vendor - generic term to include Original Equipment Manufacturer (OEM), reseller,

Value-Added Reseller (VAR), product assembler, systems integrator, and similar. Full IQS Certification - a complete set of test data covering all IQS requirements is submitted Fast Track IQS Certification -a partial set of test data covering defined IQS requirements is

submitted

APPENDIX F REFERENCES

[ANSI/NIST] -National Institute of Standards and Technology’s Data Format for the Interchange of Fingerprint, Facial, & Scar Mark & Tattoo (SMT) Information, ANSI/NIST-ITL 1-2000, NIST Special Publication 500-245.

[EFTS] - Federal Bureau of Investigation’s Electronic Fingerprint Transmission Specification, FBI-CJIS-RS-0010 (Vxxxx), dated xxxxxx.

[TestProcedures] - Federal Bureau of Investigation’s Test Procedures for Verifying IAFIS Image Quality Requirements for Fingerprint Scanners and Printers, FBI-CJIS-TD-xxxx, dated xxx.