Re: HDTV icc profile
Re: HDTV icc profile
- Subject: Re: HDTV icc profile
- From: Shadi el-Hajj <email@hidden>
- Date: Tue, 25 Mar 2003 09:40:52 +0100
hi,
thanks all for your help, let me try to get this straight :
A.K.A, sRGB IEC61966-2.1, available in Photoshop v6 and higher.
sRGB uses the HDTV chromaticies of ITU-R 709-2. HDTV monitors have a gamma
response of 2.2 and white point of 6500K.
but does this mean sRGB and ITU-R bt.709 are strictly identical ? they
have the same whitepoint and chromaticies that's for granted. however
ITU-R bt.709 specifies:
Overall opto-electronic transfer characteristics at source(1)
V = 1.099 L<superscript>0.45 ? 0.099 for 1 ? L ? 0.018
V = 4.500 L for 0.018 > L ? 0
where:
L : luminance of the image 0 ? L ? 1
V : corresponding electrical signal
and then:
Conceptual non-linear pre-correction of primary signals: gamma = 0.45
what i don't understand is how that relates to gamma 2.2 ? (excuse my
ignorance if i am saying a heresy here).
moreover, the quatization levels for 8 bit state that black level should
be 16 and nominal peak 235, doesn't this mean that the original 0-255
signal; should be remapped to fit the 16-235 range ?
thanks again.
cheers,
shadi
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