<s>
The	O
Windows	O
Imaging	O
Format	O
(	O
WIM	O
)	O
is	O
a	O
file-based	O
disk	B-Application
image	I-Application
format	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
Microsoft	O
to	O
help	O
deploy	O
Windows	B-Application
Vista	I-Application
and	O
subsequent	O
versions	O
of	O
the	O
Windows	O
operating	B-General_Concept
system	I-General_Concept
family	O
,	O
as	O
well	O
as	O
Windows	B-Device
Fundamentals	I-Device
for	I-Device
Legacy	I-Device
PCs	I-Device
.	O
</s>
<s>
Like	O
other	O
disk	B-Application
image	I-Application
formats	O
,	O
a	O
WIM	O
file	B-Operating_System
contains	O
a	O
set	O
of	O
files	O
and	O
associated	O
filesystem	B-Application
metadata	O
.	O
</s>
<s>
However	O
,	O
unlike	O
sector-based	O
formats	O
(	O
such	O
as	O
ISO	B-General_Concept
or	O
VHD	O
)	O
,	O
WIM	O
is	O
file-based	O
:	O
the	O
fundamental	O
unit	O
of	O
information	O
in	O
a	O
WIM	O
is	O
a	O
file	B-Operating_System
.	O
</s>
<s>
The	O
primary	O
advantages	O
of	O
being	O
file-based	O
is	O
hardware	O
independence	O
and	O
single-instance	B-Application
storage	I-Application
of	O
a	O
file	B-Operating_System
referenced	O
multiple	O
times	O
in	O
the	O
filesystem	B-Application
tree	O
.	O
</s>
<s>
Since	O
the	O
files	O
are	O
stored	O
inside	O
a	O
single	O
WIM	O
file	B-Operating_System
,	O
the	O
overhead	O
of	O
opening	O
and	O
closing	O
many	O
individual	O
files	O
is	O
reduced	O
.	O
</s>
<s>
The	O
cost	O
of	O
reading	O
or	O
writing	O
many	O
thousands	O
of	O
individual	O
files	O
on	O
the	O
local	O
disk	O
is	O
negated	O
by	O
hardware	O
and	O
software-based	O
disk	B-Device
caching	I-Device
as	O
well	O
as	O
sequential	O
reading	O
and	O
writing	O
of	O
the	O
data	O
.	O
</s>
<s>
WIM	O
files	O
can	O
contain	O
multiple	O
disk	B-Application
images	I-Application
,	O
which	O
are	O
referenced	O
either	O
by	O
their	O
numerical	O
index	O
or	O
by	O
their	O
unique	O
name	O
.	O
</s>
<s>
Due	O
to	O
the	O
use	O
of	O
single-instance	B-Application
storage	I-Application
,	O
the	O
more	O
each	O
successive	O
disk	B-Application
image	I-Application
has	O
in	O
common	O
with	O
previous	O
images	O
added	O
to	O
the	O
WIM	O
file	B-Operating_System
,	O
the	O
less	O
new	O
data	O
will	O
be	O
added	O
.	O
</s>
<s>
WIM	O
images	O
can	O
be	O
made	O
bootable	B-Operating_System
and	O
Windows	O
boot	B-Application
loader	I-Application
supports	O
booting	B-Operating_System
Windows	O
from	O
a	O
WIM	O
file	B-Operating_System
.	O
</s>
<s>
Windows	O
Setup	O
DVD	O
in	O
Windows	B-Application
Vista	I-Application
and	O
later	O
use	O
such	O
WIM	O
files	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
BOOT.WIM	O
contains	O
a	O
bootable	B-Operating_System
version	O
of	O
Windows	O
PE	O
from	O
which	O
the	O
installation	O
is	O
performed	O
.	O
</s>
<s>
Since	O
Windows	B-Device
8.1	I-Device
,	O
the	O
size	O
of	O
Windows	O
directory	O
can	O
be	O
reduced	O
by	O
moving	O
system	O
files	O
into	O
compressed	O
WIM	O
images	O
stored	O
on	O
a	O
separate	O
hidden	O
partition	O
(	O
WIMBoot	O
)	O
.	O
</s>
<s>
Since	O
Windows	B-Operating_System
10	I-Operating_System
,	O
system	O
files	O
can	O
be	O
compressed	O
on	O
the	O
system	O
disk	O
(	O
CompactOS	O
)	O
.	O
</s>
<s>
WIM	O
supports	O
three	O
families	O
of	O
LZ77-based	O
compression	O
algorithms	O
in	O
ascending	O
ratio	O
and	O
descending	O
speed	O
:	O
XPRESS	O
,	O
LZX	B-Device
,	O
and	O
LZMS	O
.	O
</s>
<s>
The	O
former	O
two	O
use	O
Huffman	B-General_Concept
encoding	I-General_Concept
,	O
while	O
the	O
latter	O
uses	O
adaptive	O
Huffman	B-General_Concept
encoding	I-General_Concept
with	O
range	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
There	O
is	O
also	O
support	O
for	O
solid	B-General_Concept
compression	I-General_Concept
.	O
</s>
<s>
Both	O
solid	B-General_Concept
compression	I-General_Concept
and	O
LZMS	O
are	O
introduced	O
more	O
recently	O
,	O
in	O
WIMGAPI	O
from	O
Windows	O
8	O
and	O
DISM	O
from	O
Windows	B-Device
8.1	I-Device
.	O
</s>
<s>
ImageX	O
is	O
the	O
command-line	O
tool	O
used	O
to	O
create	O
,	O
edit	O
and	O
deploy	O
Windows	O
disk	B-Application
images	I-Application
in	O
the	O
Windows	O
Imaging	O
Format	O
.	O
</s>
<s>
Starting	O
with	O
Windows	B-Application
Vista	I-Application
,	O
Windows	O
Setup	O
uses	O
the	O
WAIK	O
API	O
to	O
install	O
Windows	O
.	O
</s>
<s>
It	O
has	O
been	O
used	O
since	O
pre-RC	O
(	O
release	O
candidates	O
)	O
of	O
Windows	B-Application
Vista	I-Application
.	O
</s>
<s>
the	O
one	O
the	O
user	O
is	O
running	O
)	O
or	O
an	O
offline	O
image	O
within	O
a	O
folder	O
or	O
WIM	O
file	B-Operating_System
.	O
</s>
<s>
However	O
,	O
DISM	O
deprecated	B-General_Concept
ImageX	O
in	O
Windows	O
8	O
.	O
</s>
<s>
This	O
library	O
can	O
be	O
used	O
on	O
Unix-like	B-Operating_System
systems	I-Operating_System
,	O
as	O
well	O
as	O
on	O
Windows	O
.	O
</s>
<s>
Thanks	O
to	O
this	O
project	O
,	O
Linux	B-Application
distributions	O
now	O
have	O
their	O
own	O
imagex	O
clone	O
called	O
wimlib-imagex	O
,	O
which	O
allows	O
mounting	O
WIM	O
images	O
and	O
managing	O
them	O
(	O
read/write	O
)	O
like	O
any	O
other	O
block-storage	O
provider	O
.	O
</s>
<s>
As	O
WIM	O
images	O
use	O
somewhat	O
common	O
compression	O
algorithms	O
,	O
they	O
can	O
be	O
accessed	O
by	O
using	O
file	B-Application
archivers	I-Application
like	O
7-Zip	B-Language
.	O
</s>
<s>
For	O
other	O
operating	B-General_Concept
systems	I-General_Concept
that	O
might	O
not	O
support	O
this	O
format	O
,	O
it	O
is	O
still	O
possible	O
to	O
convert	O
.wim	O
images	O
to	O
the	O
more	O
commonly	O
used	O
ISO	B-General_Concept
image	I-General_Concept
using	O
the	O
Windows	O
Assessment	O
and	O
Deployment	O
Kit	O
on	O
Windows	O
.	O
</s>
