<s>
Acorn	B-Operating_System
is	O
a	O
raster	B-Application
graphic	I-Application
editor	I-Application
for	O
macOS	B-Application
developed	O
by	O
August	O
Mueller	O
of	O
Flying	O
Meat	O
Inc	O
,	O
based	O
out	O
of	O
Mukilteo	O
,	O
Washington	O
,	O
United	O
States	O
.	O
</s>
<s>
Acorn	B-Operating_System
was	O
first	O
released	O
on	O
September	O
10	O
,	O
2007	O
and	O
was	O
built	O
upon	O
the	O
framework	O
of	O
a	O
previous	O
image	B-Application
editing	I-Application
application	O
of	O
Flying	O
Meat	O
Inc.	O
,	O
FlySketch	O
.	O
</s>
<s>
Acorn	B-Operating_System
makes	O
extensive	O
use	O
of	O
Apple	O
's	O
Core	B-Operating_System
Image	I-Operating_System
framework	O
for	O
its	O
image	O
processing	O
,	O
.	O
</s>
<s>
The	O
native	O
file	O
format	O
of	O
Acorn	B-Operating_System
is	O
.acorn	O
.	O
</s>
<s>
Acorn	B-Operating_System
combines	O
vector	O
drawing	O
with	O
bitmap	O
editing	O
,	O
and	O
has	O
been	O
described	O
as	O
an	O
alternative	O
to	O
Photoshop	B-Operating_System
.	O
</s>
<s>
Key	O
features	O
of	O
Acorn	B-Operating_System
include	O
image	O
filters	O
,	O
a	O
custom	O
color	O
picker	O
,	O
a	O
brush	O
designer	O
,	O
and	O
image	B-Application
editing	I-Application
tools	O
such	O
as	O
crop	O
,	O
erase	O
,	O
paint	O
,	O
select	O
,	O
pan	O
,	O
zoom	O
,	O
move	O
,	O
clone	O
,	O
smudge	O
,	O
dodge	O
,	O
and	O
burn	O
.	O
</s>
