Bio-medical Ontologies Maintenance and Change Management

Multimedia Medical Databases 131
regions and attributes which are the most important in the determination of the
similarity.
At Craiova we studied the content-based region query process on a database
with medical images from digestive area captured by an endoscope. The color
regions were obtained using the color set back-projection algorithm. The reasons
for making this study are:
• There are not so many studies made on medical color images from the digestive
area, although the number of these images, acquired in the diagnosis process, is
high
• Extraction of color regions from database containing nature images provided
good results. That is why we tried this algorithm on color medical images
• In content-based region query on medical images collections, the specialist
chooses one or several detected regions for querying the database. The purpose
is the retrieval of images that are similar by color, texture or both; this can be
useful for clarifying some uncertain diagnosis or seeing the evolution and the
treatment for images with the same diagnosis; another utilization can be in
medical teaching – can be useful for students to see the important color regions
from medical images, or images that contain the similar color regions.
Taking into account that the color information of each region is stored as a
color binary set, the color similarity between two regions may be computed using
the quadratic distance between binary sets sq and st that is given by the following
equation [86]:
d
f
q , t
=
M −1
M −1
∑ ∑ ( s q [ m 0 ] − st
[ m 0 ] ) a m ( [ 1]
− [ 1]
)
0 m s 1 q m st
m
m 0 = 0 m 1 = 0
Other two important distances are taken into consideration:
1. The distance in area between two regions q and t [86]:
d = area − area
a
q , t
q
t
.
.
(5.2)
(5.3)
2. The distance in MBR width (w) and height (h) between two regions q and t
[86]:
d f
q,t
( ) ( ) 2
2
w − w + h h
s
d q , t = q t q − t
.
(5.4)
The single region distance is given by the weighted sum of the color feature
, area da
distances [86].
q,t and spatial extent ds
q,t
a
s
f
D tot = α a ⋅ d q , t + α s ⋅ d q , t + α f ⋅ d q , t
.
(5.5)