<s>
In	O
image	B-Application
editing	I-Application
,	O
a	O
curve	O
is	O
a	O
remapping	O
of	O
image	O
tonality	O
,	O
specified	O
as	O
a	O
function	O
from	O
input	O
level	O
to	O
output	O
level	O
,	O
used	O
as	O
a	O
way	O
to	O
emphasize	O
colours	O
or	O
other	O
elements	O
in	O
a	O
picture	O
.	O
</s>
