[opendtv] Re: New Chips Improve Color TV Dramatically
- From: jeroen.stessen@xxxxxxxxxxx
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 30 Jun 2004 13:39:18 +0200
Hello all,
Doug McDonald wrote:
> I do not agree. The blues are near identical.
> The reds are very close.
> The greens except the original NTSC (and Adobe RGB)
> green are very close. The original NTSC is wildly
> different from all the others (except Adobe RBG), and
> is wildly inferior. The NTSC green is green, the
> other are a rather sickly yellow green.
But we do agree on that ! There is a confusion.
Please read my original statement again:
>> 1 NTSC 1953: R=(0.670,0.330) G=(0.210,0.710) B=(0.140,0.080)
>> 2 SMPTE RP145: R=(0.630,0.340) G=(0.310,0.595) B=(0.155,0.070)
>> 3 EBU T.3213: R=(0.640,0.330) G=(0.290,0.600) B=(0.150,0.060)
>> 4 ITU R.709: R=(0.640,0.330) G=(0.300,0.600) B=(0.150,0.060)
>> 5 (e-)sRGB: R=(0.640,0.330) G=(0.300,0.600) B=(0.150,0.060)
>> 6 AdobeRGB: R=(0.640,0.330) G=(0.210,0.710) B=(0.150,0.060)
>>
>> Line 1 is the original NTSC standard, which has been OBSOLETE
>> for many years now ! Line 2 is its successor for "480i" (SDTV),
>> also known as "SMPTE C". Line 3 is its European counterpart,
>> also referred to as "PAL/Secam". Line 4 is the USA standard
>> for HDTV, which takes the red and blue from EBU, and the green
>> is an average of SMPTE and EBU green. Note that the primaries
>> vary only insignificantly between these 3 standards!
I specifically tried to refer only to lines 2,3,4. Not 1.
Of course the greens of NTSC and AdobeRGB are significantly
different from the other greens, at least numerically in
this (x,y) colour space. Nobody disputes that ! (Mark... ?)
Long ago I was told in a TV course that the NTSC green
primary was abandoned early because it was made with a
very slow oscilloscope phosphor. (Was that "P33" ??)
While that is great for suppressing flicker on an
oscilloscope image, it creates nasty motion smear on a
TV. Therefore it had to be replaced by a faster green
phosphor, unfortunately with a less saturated colour.
But luckily the eye of the "standard human observer" is
not very sensitive for shades of green, so this was not
a major problem. To put it in Mark's words: in another
perceptually uniform colour space, the NTSC and sRGB
greens are not so very far apart. Good enough for TV.
Writing this, it makes me wonder about the benefit of
AdobeRGB over sRGB. Apparently there are applications
that are more critical than TV. Rumour has it that the
green primary of AdobeRGB was selected by accident...
But it has been happily adopted by some digital camera
makers, I know that Canon lets you choose to use it.
Greetings,
-- Jeroen.
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| From: Jeroen H. Stessen | E-mail: Jeroen.Stessen@xxxxxxxxxxx |
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