Image Retrieval from a Forensic Cartridge Case Database - Multimedia Database Retrieval: Technology and Applications - page 155

1

0.5

0

-0.5

-1

0 20 40 60 80

No.

40 40

30 30

20 20

10 10

0 0

0 10 20 30 40 0 10 20 30 40

Real t x Real t y

Fig. 6.6 Registration error by translation: ( top panel ) mean square error of image registration
from translation of 80 couple images from 0 to 40 pixels; ( bottom panel ) comparing the real and
estimated values of translation parameters

4 150

3

100

2

50

1

0 0

0 50 100 150 0 50 100 150

ʸ [degree] Real ʸ [degree]

Fig. 6.7 Registration error by rotation: ( left ) mean square error of image registration from rotation
of 36 couple images from 0 to 175 ⓦ ,( right ) comparing between the real and estimated values of
rotation parameters

6.3 ECA-Based Image-Matching Method

One of the critical parts of a matching operation is the creation of ECAs from
the acquired images. This is particularly true for practice cartridge-case images,
which contain a lot of random masks that are not relevant to the matching operation.
These random masks are consciously ignored by a human examiner during his/her