Statistical Analysis of Widths and Heights of Fingerprint Images 

in Terms of Ages from Segmentation Data 

October 15, 2008 

Jin Chu Wu 

In the July Report, the statistical analysis of widths and heights of fingerprint images from 

segmentation data was presented. In this October Report, the statistical analysis in terms of ages 

is carried out. All these results will provide references for designing targets for the evaluation of 

the fast tenprint capture (FTC) devices. As stated in the draft of “Specifications for Fast Tenprint 

Capture Devices”, Version 1.0, one of the three aspects in the evaluation of FTC devices is the 

absolute measurement, i.e., stipulating the specifications and designing targets to implement 

specifications. One of many aspects in the absolute measurement is the geometric accuracy. And 

the geometric accuracy is related to the finger sizes. 

As pointed out in the July Report, in order to obtain the finger sizes, one way is to collect 

samples. For instance, the human finger sizes can be collected in any public areas. Then, an 

inferential statistical analysis follows. The alternative is to analyze the segmentation data. 

Here we need to emphasize again that while analyzing the segmentation data, 1) the sizes of two 

thumbs cannot be obtained, 2) only the widths and heights but not the thicknesses of the fingers 

can be estimated, 3) the widths and heights shown in the segmentation data are the widths and 

heights of fingerprint images, respectively, that are smaller than the widths and heights of real 

fingers, which is because only the front part of a finger touches the platen of a live scanner to 

form a flat fingerprint image during a capture process. This third point is the most important 

issue. Nonetheless, the analysis of the segmentation data can provide some information, for 

example, the proportion between two finger sizes, etc., for designing the simulated fingers to be 

the targets in the absolute measurement. 

The segmentation data were provided by Craig Watson’s subgroup and they included data from 

dos3s and lacnty (LA County). Some data contained the age information, but some data didn’t. 

In addition, some data were corrupted, in which the sizes of width and/or height were 

inappropriately recorded, or the birth date and the capture date did not match properly, or the age 

of the subject was less than 10. The corrupted data were deleted. 

The set of the segmentation data is the direct product of the set of gender (male and female), the 

set of eight fingers (R2, R3, R4, R5, L7, L8, L9, and L10), and the set of the dimension (width 

and height). They can be mathematically expressed as, 

{segmentation data} = {male, female} ⊗ {R2, R3, R4, R5, L7, L8, L9, L10} ⊗ {width, height} 

As a result, the segmentation data can be subdivided into 32 subsets in terms of gender, finger, 

and the dimension, such as M_R2_w, M_R2_h, etc. 

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Further, as far as the age is concerned, the age is divided into three groups: age 10 to 30, age 31 

to 60, and age 61 and up. Therefore, the total is 96 subsets. All these 96 subsets are denoted, 

respectively, as M_R2_w_30, M_R2_w_60, M_R2_w_90, and so on. 

In each subset of the 96 subsets, the statistical analysis was carried out. And the results, such as 

the number of data (i.e., the sample size), the median, the mean, the standard error (SE) of the 

sample mean, and the 95% confidence interval (CI) of the sample mean, are provided. The unit 

of the sizes in the segmentation data was in pixel, as requested, which is more accurate than 

other units. However, only the results in terms of the unit millimeter, which were converted from 

the results using the unit of pixel, are provided. Otherwise, too many tables would be listed. The 

results in the unit of pixel are available on request. 

The results of the statistical analysis are listed from Table 1 to Table 6. It is shown in these six 

tables that the median and the mean are quite close in each subset. This indicates that the 

distribution in each subset is quite symmetric. Therefore, the standard errors and the 95% 

confidence intervals of the sample mean instead of the median were computed. The standard 

error for female is generally greater than the one for male. This is because the sample size for 

female is smaller than the sample size for male in the segmentation data, especially for the age 

group of “10 to 30”, and “31 to 60”. 

Generally speaking, it follows from these six tables that the fingerprint image sizes extracted 

from the segmentation data do not vary too much with respect to the age. Moreover, by 

comparing these six tables with the two tables in the unit of millimeter as shown in the July 

Report, it seems that while designing the targets of fingers, the age may not be a factor for the 

majority of cases. 

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Fingers Number Median Mean SE 95% CI 

M_R2_w_30 11922 14.63 14.66 0.0127 (14.63, 14.68) 

M_R3_w_30 11922 15.29 15.17 0.0132 (15.15, 15.20) 

M_R4_w_30 11922 14.63 14.70 0.0122 (14.68, 14.73) 

M_R5_w_30 11922 13.82 13.65 0.0137 (13.62, 13.68) 

M_L7_w_30 11275 14.53 14.40 0.0127 (14.37, 14.42) 

M_L8_w_30 11275 15.04 14.97 0.0137 (14.94, 15.00) 

M_L9_w_30 11275 14.43 14.36 0.0127 (14.33, 14.38) 

M_L10_w_30 11275 13.41 13.37 0.0142 (13.34, 13.39) 

F_R2_w_30 5829 13.31 13.31 0.0163 (13.28, 13.34) 

F_R3_w_30 5829 13.72 13.64 0.0183 (13.60, 13.68) 

F_R4_w_30 5829 13.41 13.40 0.0168 (13.36, 13.43) 

F_R5_w_30 5829 12.19 12.17 0.0188 (12.13, 12.21) 

F_L7_w_30 5799 13.00 13.00 0.0163 (12.97, 13.03) 

F_L8_w_30 5799 13.31 13.28 0.0183 (13.24, 13.31) 

F_L9_w_30 5799 13.00 12.89 0.0173 (12.85, 12.92) 

F_L10_w_30 5799 11.58 11.66 0.0188 (11.62, 11.70) 

Table 1 The statistical results for the widths in millimeter of the 2nd, 3rd, 4th, and 5th finger of the right hand 

and the 7th, 8th, 9th, and 10th finger of the left hand for both male and female, in the age group of 10 to 30, 

where the number stands for the sample size. 

Fingers Number Median Mean SE 95% CI 

M_R2_h_30 11922 23.98 23.86 0.0203 (23.82, 23.90) 

M_R3_h_30 11922 24.38 24.34 0.0244 (24.29, 24.39) 

M_R4_h_30 11922 24.79 24.80 0.0229 (24.76, 24.85) 

M_R5_h_30 11922 21.54 21.47 0.0224 (21.43, 21.51) 

M_L7_h_30 11275 23.57 23.67 0.0198 (23.63, 23.71) 

M_L8_h_30 11275 24.38 24.14 0.0264 (24.08, 24.19) 

M_L9_h_30 11275 24.79 24.87 0.0229 (24.83, 24.91) 

M_L10_h_30 11275 21.13 20.94 0.0254 (20.88, 20.98) 

F_R2_h_30 5829 21.95 21.76 0.0279 (21.71, 21.82) 

F_R3_h_30 5829 22.45 22.43 0.0325 (22.37, 22.50) 

F_R4_h_30 5829 22.35 22.34 0.0325 (22.28, 22.41) 

F_R5_h_30 5829 19.51 19.24 0.0305 (19.18, 19.30) 

F_L7_h_30 5799 21.64 21.56 0.0274 (21.50, 21.61) 

F_L8_h_30 5799 22.35 22.33 0.0315 (22.27, 22.39) 

F_L9_h_30 5799 22.25 22.25 0.0305 (22.19, 22.31) 

F_L10_h_30 5799 19.10 19.06 0.0310 (19.00, 19.12) 

Table 2 The statistical results for the heights in millimeter of the 2nd, 3rd, 4th, and 5th finger of the right hand 

and the 7th, 8th, 9th, and 10th finger of the left hand for both male and female, in the age group of 10 to 30, 

where the number stands for the sample size. 

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Fingers Number Median Mean SE 95% CI 

M_R2_w_60 12383 15. 44 15.22 0.0127 (15.20, 15.25) 

M_R3_w_60 12383 15. 44 15.60 0.0132 (15.57, 15.62) 

M_R4_w_60 12383 15.14 15.13 0.0127 (15.11, 15.16) 

M_R5_w_60 12383 13.82 13.92 0.0142 (13.89, 13.95) 

M_L7_w_60 11818 15.04 15.02 0.0127 (15.00, 15.05) 

M_L8_w_60 11818 15.44 15.48 0.0132 (15.45, 15.50) 

M_L9_w_60 11818 14.94 14.86 0.0127 (14.83, 14.88) 

M_L10_w_60 11818 13.82 13.71 0.0142 (13.68, 13.74) 

F_R2_w_60 5891 13.82 13.95 0.0178 (13.91, 13.98) 

F_R3_w_60 5891 14.22 14.16 0.0188 (14.12, 14.19) 

F_R4_w_60 5891 13.82 13.75 0.0173 (13.71, 13.78) 

F_R5_w_60 5891 12.29 12.38 0.0193 (12.34, 12.42) 

F_L7_w_60 5884 13.61 13.58 0.0173 (13.55, 13.62) 

F_L8_w_60 5884 13.82 13.79 0.0183 (13.76, 13.83) 

F_L9_w_60 5884 13.21 13.26 0.0178 (13.23, 13.30) 

F_L10_w_60 5884 11.99 11.91 0.0193 (11.87, 11.95) 

Table 3 The statistical results for the widths in millimeter of the 2nd, 3rd, 4th, and 5th finger of the right hand 

and the 7th, 8th, 9th, and 10th finger of the left hand for both male and female, in the age group of 31 to 60, 

where the number stands for the sample size. 

Fingers Number Median Mean SE 95% CI 

M_R2_h_60 12383 23.98 23.91 0.0198 (23.87, 23.95) 

M_R3_h_60 12383 24.38 24.24 0.0234 (24.19, 24.29) 

M_R4_h_60 12383 24.38 24.48 0.0224 (24.44, 24.52) 

M_R5_h_60 12383 21.54 21.27 0.0218 (21.23, 21.32) 

M_L7_h_60 11818 23.77 23.78 0.0198 (23.74, 23.82) 

M_L8_h_60 11818 24.38 24.20 0.0249 (24.15, 24.25) 

M_L9_h_60 11818 24.79 24.71 0.0218 (24.67, 24.76) 

M_L10_h_60 11818 21.13 21.07 0.0234 (21.02, 21.11) 

F_R2_h_60 5891 21.95 21.77 0.0284 (21.72, 21.83) 

F_R3_h_60 5891 22.35 22.31 0.0325 (22.25, 22.38) 

F_R4_h_60 5891 21.95 22.05 0.0320 (21.99, 22.11) 

F_R5_h_60 5891 19.00 18.99 0.0300 (18.93, 19.05) 

F_L7_h_60 5884 21.64 21.58 0.0284 (21.53, 21.64) 

F_L8_h_60 5884 22.25 22.23 0.0320 (22.17, 22.30) 

F_L9_h_60 5884 21.95 21.98 0.0305 (21.92, 22.04) 

F_L10_h_60 5884 18.90 18.87 0.0305 (18.81, 18.93) 

Table 4 The statistical results for the heights in millimeter of the 2nd, 3rd, 4th, and 5th finger of the right hand 

and the 7th, 8th, 9th, and 10th finger of the left hand for both male and female, in the age group of 31 to 60, 

where the number stands for the sample size. 

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Fingers Number Median Mean SE 95% CI 

M_R2_w_90 1004 15.85 15.89 0.0503 (15.80, 15.99) 

M_R3_w_90 1004 16.26 16.08 0.0488 (15.98, 16.18) 

M_R4_w_90 1004 15.65 15.68 0.0472 (15.59, 15.78) 

M_R5_w_90 1004 13.87 13.99 0.0544 (13.89, 14.10) 

M_L7_w_90 1013 15.95 15.87 0.0523 (15.77, 15.98) 

M_L8_w_90 1013 16.15 15.98 0.0478 (15.89, 16.08) 

M_L9_w_90 1013 15.44 15.33 0.0488 (15.24, 15.43) 

M_L10_w_90 1013 13.82 13.84 0.0549 (13.74, 13.95) 

F_R2_w_90 1003 15.04 14.95 0.0457 (14.86, 15.04) 

F_R3_w_90 1003 15.14 14.99 0.0472 (14.90, 15.08) 

F_R4_w_90 1003 14.63 14.48 0.0452 (14.39, 14.56) 

F_R5_w_90 1003 13.00 12.93 0.0503 (12.83, 13.03) 

F_L7_w_90 1004 14.53 14.40 0.0472 (14.31, 14.50) 

F_L8_w_90 1004 14.63 14.53 0.0462 (14.44, 14.62) 

F_L9_w_90 1004 13.82 13.91 0.0457 (13.82, 14.00) 

F_L10_w_90 1004 12.19 12.22 0.0508 (12.12, 12.32) 

Table 5 The statistical results for the widths in millimeter of the 2nd, 3rd, 4th, and 5th finger of the right hand 

and the 7th, 8th, 9th, and 10th finger of the left hand for both male and female, in the age group of 61 and up, 

where the number stands for the sample size. 

Fingers Number Median Mean SE 95% CI 

M_R2_h_90 1004 24.28 24.11 0.0762 (23.96, 24.26) 

M_R3_h_90 1004 24.38 24.37 0.0813 (24.21, 24.53) 

M_R4_h_90 1004 23.88 23.87 0.0828 (23.71, 24.04) 

M_R5_h_90 1004 21.03 20.88 0.0823 (20.72, 21.04) 

M_L7_h_90 1013 24.28 24.10 0.0747 (23.95, 24.24) 

M_L8_h_90 1013 24.38 24.43 0.0823 (24.27, 24.59) 

M_L9_h_90 1013 24.28 24.21 0.0798 (24.06, 24.37) 

M_L10_h_90 1013 21.13 20.90 0.0823 (20.74, 21.06) 

F_R2_h_90 1003 21.95 22.04 0.0737 (21.89, 22.18) 

F_R3_h_90 1003 22.35 22.39 0.0798 (22.24, 22.55) 

F_R4_h_90 1003 21.74 21.67 0.0716 (21.53, 21.81) 

F_R5_h_90 1003 18.69 18.62 0.0721 (18.48, 18.76) 

F_L7_h_90 1004 21.64 21.58 0.0716 (21.44, 21.72) 

F_L8_h_90 1004 22.15 22.21 0.0767 (22.06, 22.36) 

F_L9_h_90 1004 21.44 21.51 0.0732 (21.36, 21.65) 

F_L10_h_90 1004 18.69 18.50 0.0777 (18.35, 18.65) 

Table 6 The statistical results for the heights in millimeter of the 2nd, 3rd, 4th, and 5th finger of the right hand 

and the 7th, 8th, 9th, and 10th finger of the left hand for both male and female, in the age group of 61 and up, 

where the number stands for the sample size. 

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