[opendtv] RGB Mainia -try again

  • From: "Prinyar Boon" <Prinyar.Boon@xxxxxxxxxxxxxxx>
  • To: "opendtv (freelists)" <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 14 Jan 2005 13:34:25 -0000

OK=20-=20try=20again,

The=20problem=20we=20have=20run=20into=20in=20the=20TV=20world=20is=20the=20=
interpretation=20of
the=20coding=20range=20-=20specifically=20the=20"meaning"=20of=20black=20a=
nd=20white.=20=20This
is=20something=20that=20Alan=20and=20I=20have=20kicked=20around...Take=20t=
he=20meaning=20of
'white'

In=20an=208=20bit=20ITU-R=20BT.601=20system=20the=20code=20for=20'white'=20=
is=20235=20[decimal]=20-
all=20seems=20clear=20and=20simple.

However=20-=20if=20you=20look=20at=20the=20taking=20characteristics=20of=20=
the=20camera=20-=20and
specifcally=20its=20optoelectronic=20transfer=20function:=20there=20are=20=
at=20least=202
meanings=20of=20white.=20=20The=20first=20is=20established=20by=20the=20kn=
ee,=20the=20second=20is
the=20area=20which=20is=20used=20to=20cope=20with=20specular=20highlights.=
=20=20The=20position
of=20the=20knee=20-=20and=20the=20slope=20of=20the=20compression=20for=20h=
ighlights=20are=20both
under=20control=20of=20the=20camera=20man.

So=20what=20do=20you=20do?=20Do=20you=20set=20the=20knee=20[I'll=20call=20=
this=20the=20mid=20to=20large
area=20white]=20for=20235,=20and=20allow=20speculars=20to=20go=20up=20to=20=
the=20link=20clip
limit.=20=20Or=20do=20you=20set=20the=20speculars=20for=20235?....or=20do=20=
you=20make=20them=20both
the=20same?

At=20the=20display=20end,=20a=20conventional=20TV=20[not=20a=20broadcast=20=
monitor]=20-=20will
allow=20the=20small=20area=20luminance=20level=20to=20reach=20say=20450cd/=
m2.=20=20However=20the
large=20area=20light=20output=20will=20be=20limited=20to=20say=20120cd/m2.=
=20=20So=20a=20tellie=20-
as=20the=20ability=20to=20have=20a=20stab=20at=20reproducing=20specular=20=
highlights.....and
does=20this=20by=20the=20miracle=20of=20beam=20current=20limiting.=20=20It=
=20also=20manges=20to
interpret=20small=20areas=20of=20code=20235=20as=20specular.=20=20This=20i=
s=20probably=20a=20good
thing.

Now=20-=20you=20try=20doing=20that=20on=20either=20a=20PWM=20based=20or=20=
light=20valve=20display.
Interestingly=20a=20plasma=20panel=20does=20have=20a=20related=20small/lar=
ge=20area=20white
characteristc=20-=20based=20on=20overall=20power=20limiting,=20and=20Panas=
onic=20have
engineered=20some=20dynamic=20APL=20based=20processing=20into=20their=20pr=
ofessional
projectors.=20=20However=20this=20combination/mixed=20melange=20of=20displ=
ay
characteristics=20in=20the=20field=20just=20makes=20things=20even=20worse,=
=20we=20have=20NO
chance=20of=20achieving=20a=20controlled=20transfer=20between=20broadcast=20=
monitoring
and=20home=20viewing.

In=20addition=20to=20this=20-=20because=20BT.601=20does=20not=20distinguis=
h=20between
specular=20highlights=20and=20medium/large=20area=20white...we=20do=20not=20=
have=20any
simple=20mechanism=20to=20signal=20to=20the=20display=20that=20this=20is=20=
a=20specular
region...which=20has=20had=20this=20compression=20slope=20applied=20by=20t=
he=20camera.=20=20To
compound=20matters=20-=20if=20you=20even=20tried=20to=20use=20this=20specu=
lar=20region=20then=20a)
Some=20alarm=20in=20some=20gamut=20legaliser=20would=20trigger=20and=20som=
eone=20would=20wind
in=20the=20clippers.=20And/Or=20b)=20BECAUSE=20we=20did=20not=20codify=20t=
he=20the=20use=20of=20this
region,=20and=20because=20we=20did=20not=20say=20that=20all=20digital=20di=
splays=20should=20have
a=20soft=20clipper......then...if=20the=20broadcaster=20did=20not=20apply=20=
the=20soft
clipper=20-=20the=20display=20would=20probably=20hard=20clip=20-=20which=20=
would=20be=20even
worse.

So=20-=20this=20is=20a=20subtle=20and=20unintended=20consequence=20which=20=
is=20due=20to=20a
simplistic=20interpretation=20of=20the=20coding=20range=20[based=20on=20wh=
at=20worked=20for
CRT's]=20and=20the=20switch=20to=20digital=20matrix=20displays.

The=20whites=20are=20relatively=20straight=20forward=20to=20explain!

Television=20is=20just=20plain=20broke...

Prin

Prinyar=20Boon
Snell=20&=20Wilcox=20Ltd
Liss=20Mill
GU33=207BD

email:=20prinyar.boon@xxxxxxxxxxxxxxx
Tel:=20+44=20(0)2392=20489=20280=20direct
Fax:=20+44=20(0)1730=20894=20341
www.snellwilcox.com

-----Original=20Message-----
From:=20opendtv-bounce@xxxxxxxxxxxxx=20[mailto:opendtv-bounce@xxxxxxxxxxxx=
g]
On=20Behalf=20Of=20Alan=20Roberts
Sent:=2014=20January=202005=2012:16
To:=20opendtv@xxxxxxxxxxxxx
Subject:=20[opendtv]=20Re:=20RGB=20mania

Not=20quite=20right=20Jeroen.=20=20ITU.601=20etc=20all=20include=20specifi=
cations=20for=20the
coding=20of=20RGB=20as=20well=20as=20YUV=20signals.=20They=20form=20a=20cl=
osed=20set.=20The=20rules
for=20Y=20also=20apply=20to=20RGB.=20Indeed,=20the=20coding=20of=20YUV=20c=
omes=20from=20a=20digital
calculation=20using=20digital=20RGB=20signals,=20each=20of=20which=20must=20=
conform=20to=20601
coding=20rules.=20At=20no=20point=20is=20there=20any=20flexibility=20in=20=
the=20coding=20of=20Y,
since=20it=20normally=20doesn't=20exist=20in=20analogue=20these=20days.

The=20headroom=20in=20the=20coding=20range=20is=20specifically=20for=20the=
=20RGB=20signals
rather=20than=20Y,=20the=20extra=20range=20that=20Y=20has=20as=20a=20resul=
t=20is=20almost
accidental.

Alan

-----=20Original=20Message=20-----
From:=20<jeroen.stessen@xxxxxxxxxxx>
To:=20<opendtv@xxxxxxxxxxxxx>
Sent:=20Friday,=20January=2014,=202005=2011:51=20AM
Subject:=20[opendtv]=20Re:=20RGB=20mania


>=20Hello,
>=203.
>=20With=20digital=20RGB=20"graphics"=20signals=20(e.g.=20DVI=20out)=20it=20=
is=20common=20to=20
>=20have=20black=20=3D=200,=20white=20=3D=20255,=20but=20with=20digital=20=
YUV=20"video"
>=20signals=20(e.g.=20ITU-R.656=20or=20SDI)=20it=20is=20common=20to=20have=
=20black=20=3D=2016,=20white

>=20=3D=20235.=20The=20Y=20signal=20has=20headroom=20that=20the=20RGB=20si=
gnals=20have=20not.=20This=20
>=20headroom=20is=20reserved=20for=20the=20ringing=20due=20to=20anti-

>=20Greetings,
>=20--=20Jeroen

Prinyar=20Boon
Snell=20&=20Wilcox=20Ltd
Liss=20Mill
GU33=207BD

email:=20prinyar.boon@xxxxxxxxxxxxxxx
Tel:=20+44=20(0)2392=20489=20280=20direct
Fax:=20+44=20(0)1730=20894=20341
www.snellwilcox.com

This=20email=20and=20any=20attachments=20is=20confidential,=20may=20be=20l=
egally=20privileged=20and=20is=20intended=20for=20the=20use=20of=20the=20a=
ddressee=20only.=20If=20you=20are=20not=20the=20intended=20recipient,=20pl=
ease=20note=20that=20any=20use,=20disclosure,=20printing=20or=20copying=20=
of=20this=20email=20is=20strictly=20prohibited=20and=20may=20be=20unlawful=
.=20If=20received=20in=20error,=20please=20delete=20this=20email=20and=20a=
ny=20attachments=20and=20confirm=20this=20to=20the=20sender.
 
 
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