CODEWITHSUNDEEP
biometrics
user1263554
user1263554

Reputation: 1

Multimode Biometrics

I have difficulty in Plotting ROC curve. In that they have plot GAR v/s FAR in percentage(for unimode bimode in biometrics). I would like to know how GAR and FAR is calculated? and how it is ploted in ROC curve?

For the reference, I have attached one plot.![enter image description here][1]

Upvotes: 0

Views: 552

Answers (1)

rgiot
rgiot

Reputation: 113

What do you mean by multimode / unimode? Is it multimodal / unimodal? If yes, plotting the ROC curve for unimal or multimodal biometric is similar...

When you evaluated your biometric system, you obtained two kinds of scores:

  • the intra scores (comparison between biometric references against queries of the same user)
  • the inter scores (comparison between biometric references against queries of other users)

Say your system uses a threshold t, and the scores are distances.

  • If you count the number of intra scores higher than t, and divide it by the total number of intra scores, you obtain the FRR.
  • If you count the number of inter scores lower or equal to t, and divide it by the total number of inter scores, you obtain the FAR.
  • GAR is 1-FRR

If you repeat the procedure for several thresholds, you obtain each time a couple of (GAR,FAR).

Then you just need to plot each couple of (FAR,GAR). The plotting method depends of course of your implementation language...

There are tons of implementations to display ROC curves with different languages on the internet. You should search a bit

Upvotes: 3

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