-
What is positive recognition?
- To je specifičen scenarij:
- Vzorec, ki gre v sistem je že znan sistemu.
Ali si nekdo, ki je že znan sistemu.
-
What is negative recognition?
- To je specifičen scenarij:
- Vzorec, ki gre v sistem še ni znan sistemu.
- Ali si nekdo ki ni znan sistemu pol te passa.
-
What is pair matching for images?
Sistem poskuša določiti, ali se 2 sliki ujemata.
-
What is verification?
Sistem poskuša določiti ali se specifična oseba ujema z eno v sistemu.
-
What is identification?
Sistem poskuša določiti ali oseba obstaja v našem sistemu.
-
What is negative authentication?
- Sistem poskuša določiti ali oseba ne pripada dooločeni skupini.
- (Black list)
-
What is deduplication?
Sistem poskuša določiti ali oseba že obstaja v sistemu, da je ne kreira še enkrat.
-
What is false match rate?
Verjetnost, da sistem vhodni vzorec klasificira napačnemu (non-match) vzorcu v bazi.
- Procenti napačnih vhodov ki so napačno sprejeti(accepted).
- Pomeni da ga je sistem sprejel čeprav ga nebi smel.
-
What is false non-match rate?
Verjetnost, da sistem ne uspe klasificirati klasificirati vhodnega vzorca.
Procenti ustreznih vhodnih vzorcev, ki so zavrženi.
-
What ROC stands for?
Receiver Operating Characteristics
-
What does CMC stands for?
- Cumulative Match Curve.
- A plot of rank measures for different n-s.
-
What is a rank measure?
Rank nam pove verjetnost da matchamo pravo osebo v n best matches produced by out system.
Rank nam pove verjetnost da se vzorec (closest match) v bazi za katerega sistem meni, da se najbolje ujema, res pravi in da se ujema z vhodno osebo.
-
How many ridges per centimeter on their fingerprints do people have?
- Male: 20.7 ridges/cm
- Female: 23.4 ridges/cm
-
What do we observe at level 1 fingerprint features?
Ridge orientation, coarse features at pixels.
-
What is singular point?
Lokacija kjer se orientacija of ridge spremeni (zavoji).
-
What are the two basic types of singular point?
- Loops
- Delta
-
What is the Core point of the fingerprint?
- Core point corresponds to the north most loop-type singular point.
-
What are the most common types of finger print patterns?
- Left and right loops 65%
- Whorls 24%
- Twin loop 4%
- Tended arch 3%
- Plain arch 4%
-
What is the resolution needed to observe L1 fingerprint features?
250 ppi
-
What is the resolution needed to observe L2 fingerprint features?
500 ppi
-
What is the resolution needed to observe L3 fingerprint features?
1000 ppi
-
What do we observe at level 2 fingerprint features?
Minutiae points, location of ridge emersions and splits
-
What are three common type of fingerprints based on how we acquire them?
- Rolled
- Plain
- Latent fingerprints
-
What do we observe at level 3 fingerprint features?
Inner holes (sweat pores) and outer contours (edges)
-
Which 5 sensors for obtaining fingerprints do we
most commonly use?
- Optical
- Capacitance
- Ultrasound reflection
- Piezo electric
- Swipe
-
What is L2 skeletonisation?
Proces kjer fingerprint ridges pretvorimo v 1 pixel široke črte.
-
Which 3 techniques may we use to evaluate the quality of fingerprints?
- Features counting:
- Slabe slike ponavadi dajo zelo veliko ali malo število of feature points, takrat zavržemo.
- NFIQ method:
- Za vsak feature point (minutae) izračunaj ridge density.
- Potem vsak blok evaluiram kvaliteto (4 = perfect quality ... 0-background)
Pixel Intensity:
-
How may we use feature counting to evaluate quality of the fingerprint?
- Slabe slike ponavadi dajo zelo veliko ali malo minutae points.
- Obdržimo le tiste odtise, ki imajo število minutae points v nekem treshold območju od do.
-
How may we use pixel intensity method to evaluate the quality of the fingerprint?
Use histogram
-
Which 3 methods may we use to improve the quality of the fingerprints?
- Hong's method
- 1D smoothing
- Short Time Fourier Transform approach
-
Which level features we use in commercial systems for fingerprints?
L1 and L2 features.
-
Which 2 types of minutae points do we know?
- Bifurcations
- Takrat, ko ima ridge piksel 3 sosednje piksle
- Endings
- Takrat, ko ima ridge piksel 1 sosedni piksel
-
How do we detect both types of minutae points?
- Bifurcations:
- Ridge neighbours == 3
- Endings:
- Ridge neighbours == 1
-
How do we trace minutae direction?
- Endings:
- Gremo po poti nazaj recimo 10 pikslov in potegnemo premico.
-
- Bifurcations:
- obtain three points and trace direction of two points whose difference is the smallest
-
What are the three steps of matching two fingerprints based on minutae points.
- Aligment Transformiramo eno sliko tako, da se prilagaja drugi.
- Correspondence:
- Najdem pare tako da združim točke ki so v območju recimo 15 pikslov, to določimo s treshold.
- Score generation:Število paired minutae points/ Vsi minutae points iz obeh slik.
-
What is a plain fingerprint?
- Fingerprint obtained when a finger directly touches the sensor.
-
What is a rolled fingerprint?
- Fingerprint obtained when a finger is rolled from one side to the other on the sensor.
-
What is latent fingerprint?
- Fingerprint obtained from uncontrolled environment such as crime scene.
|
|
