<s>
A	O
region	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
(	O
often	O
abbreviated	O
ROI	O
)	O
is	O
a	O
sample	O
within	O
a	O
data	B-General_Concept
set	I-General_Concept
identified	O
for	O
a	O
particular	O
purpose	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
medical	B-Application
imaging	I-Application
,	O
the	O
boundaries	O
of	O
a	O
tumor	O
may	O
be	O
defined	O
on	O
an	O
image	O
or	O
in	O
a	O
volume	O
,	O
for	O
the	O
purpose	O
of	O
measuring	O
its	O
size	O
.	O
</s>
<s>
In	O
geographical	B-Application
information	I-Application
systems	I-Application
(	O
GIS	B-Application
)	O
,	O
a	O
ROI	O
can	O
be	O
taken	O
literally	O
as	O
a	O
polygonal	O
selection	O
from	O
a	O
2D	O
map	O
.	O
</s>
<s>
In	O
computer	B-Application
vision	I-Application
and	O
optical	B-Application
character	I-Application
recognition	I-Application
,	O
the	O
ROI	O
defines	O
the	O
borders	B-Algorithm
of	O
an	O
object	O
under	O
consideration	O
.	O
</s>
<s>
Medical	B-Application
imaging	I-Application
standards	O
such	O
as	O
DICOM	B-Algorithm
provide	O
general	O
and	O
application-specific	O
mechanisms	O
to	O
support	O
various	O
use-cases	O
.	O
</s>
<s>
For	O
DICOM	B-Algorithm
images	O
(	O
two	O
or	O
more	O
dimensions	O
)	O
:	O
</s>
<s>
For	O
DICOM	B-Algorithm
radiotherapy	O
:	O
</s>
<s>
For	O
DICOM	B-Algorithm
time-based	O
waveforms	O
:	O
</s>
<s>
HL7	O
Clinical	O
Document	O
Architecture	O
also	O
has	O
a	O
subset	O
of	O
mechanisms	O
similar	O
to	O
(	O
and	O
intended	O
to	O
be	O
compatible	O
with	O
)	O
DICOM	B-Algorithm
for	O
referencing	O
image-related	O
spatial	O
coordinates	O
as	O
observations	O
;	O
it	O
allows	O
for	O
a	O
circle	O
,	O
ellipse	O
,	O
polyline	O
or	O
point	O
to	O
be	O
defined	O
as	O
integer	O
pixel-relative	O
coordinates	O
referencing	O
an	O
external	O
multi-media	O
image	O
object	O
,	O
which	O
may	O
be	O
of	O
a	O
consumer	O
rather	O
than	O
medical	B-Application
image	I-Application
format	O
(	O
e.g.	O
,	O
a	O
GIF	O
,	O
PNG	O
or	O
JPEG	O
)	O
.	O
</s>
<s>
In	O
Optical	B-Application
Character	I-Application
Recognition	I-Application
(	O
OCR	O
)	O
and	O
Document	B-Algorithm
Layout	I-Algorithm
Analysis	I-Algorithm
,	O
regions	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
(	O
ROIs	O
)	O
hierarchically	O
encompass	O
pages	O
,	O
text	O
or	O
graphical	O
blocks	O
,	O
down	O
to	O
individual	O
line-strip	O
images	O
,	O
word	O
and	O
character	O
image	O
boxes	O
.	O
</s>
<s>
As	O
far	O
as	O
non-medical	O
standards	O
are	O
concerned	O
,	O
in	O
addition	O
to	O
the	O
purely	O
graphic	O
markup	O
languages	O
(	O
such	O
as	O
PostScript	B-Language
or	O
PDF	B-Application
)	O
and	O
vector	O
graphic	O
(	O
such	O
as	O
SVG	B-Application
)	O
and	O
3D	O
(	O
such	O
as	O
VRML	B-Application
)	O
drawing	O
file	O
formats	O
that	O
are	O
widely	O
available	O
,	O
and	O
which	O
carry	O
no	O
specific	O
ROI	O
semantics	O
,	O
some	O
standards	O
such	O
as	O
JPEG	O
2000	O
specifically	O
provide	O
mechanisms	O
to	O
label	O
and/or	O
compress	O
to	O
a	O
different	O
degree	O
of	O
fidelity	O
,	O
what	O
they	O
refer	O
to	O
as	O
regions	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
.	O
</s>
