<s>
Chroma	B-General_Concept
dots	I-General_Concept
are	O
visual	O
artifacts	O
caused	O
by	O
displaying	O
an	O
unfiltered	O
PAL	B-Language
analogue	O
colour	O
video	O
signal	O
on	O
a	O
black-and-white	O
television	O
or	O
monitor	O
.	O
</s>
<s>
Chroma	B-General_Concept
dots	I-General_Concept
were	O
once	O
regarded	O
as	O
undesirable	O
picture	O
noise	O
,	O
but	O
recent	O
advances	O
in	O
computer	O
technology	O
have	O
allowed	O
them	O
to	O
be	O
used	O
to	O
reconstruct	O
the	O
original	O
colour	O
signal	O
from	O
black-and-white	O
recordings	O
,	O
providing	O
a	O
means	O
to	O
re-colour	O
material	O
where	O
the	O
original	O
colour	O
copy	O
is	O
lost	O
.	O
</s>
<s>
During	O
the	O
telerecording	O
process	O
,	O
it	O
was	O
normal	O
practice	O
to	O
insert	O
a	O
filter	O
circuit	O
between	O
the	O
colour	O
video	O
output	O
and	O
the	O
black-and-white	O
monitor	O
input	O
in	O
order	O
to	O
remove	O
the	O
colour	O
signal	O
and	O
prevent	O
the	O
formation	O
of	O
chroma	B-General_Concept
dots	I-General_Concept
.	O
</s>
<s>
In	O
1994	O
,	O
James	O
Insell	O
,	O
a	O
BBC	O
engineer	O
,	O
noticed	O
that	O
when	O
playing	O
back	O
a	O
copy	O
of	O
a	O
black-and-white	O
telerecording	O
through	O
colour	O
video	O
equipment	O
,	O
spurious	O
colour	O
was	O
generated	O
by	O
the	O
presence	O
of	O
chroma	B-General_Concept
dots	I-General_Concept
in	O
the	O
picture	O
.	O
</s>
<s>
He	O
theorised	O
that	O
it	O
might	O
be	O
possible	O
to	O
use	O
the	O
chroma	B-General_Concept
dots	I-General_Concept
to	O
reconstruct	O
the	O
original	O
colour	O
signal	O
,	O
and	O
in	O
2007	O
set	O
up	O
a	O
working	O
group	O
to	O
carry	O
out	O
further	O
research	O
.	O
</s>
