diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index d7bcc72..438d154 100644
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+++ b/.obsidian/workspace.json
@@ -42,18 +42,18 @@
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     "Biometric Systems/frequently asked questions/BS_oral_questions_16022021.md",
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diff --git a/Biometric Systems/notes/11. Fingerprints.md b/Biometric Systems/notes/11. Fingerprints.md
index 1d14d5a..04919c0 100644
--- a/Biometric Systems/notes/11. Fingerprints.md	
+++ b/Biometric Systems/notes/11. Fingerprints.md	
@@ -101,6 +101,8 @@ Once a fingerprint has been segmentated we can start extracting **macro-features
 
 ##### Directional map
 ~~The local orientation of the ridge line in the position [i, j] is defined as the angle $\theta(i,j)$ formed by considering the horizontal line at that point, and a point on the ridge line sufficiently closer to [i, j].~~
+
+Definizione: matrice in cui la cella [i, j] rappresenta l'angolo che la tangente alla ridge line forma con l'asse orizzontale.
 ![[Pasted image 20241127224325.png]]
 - most approaches use a grid measure (instead of measuring at each point)
 - the directional image D is a matrix in which each element denotes the average orientation of the ridge (of the tangent to the ridge) in a neighborhood of $[x_{i}, y_{i}]$