complectus Posted May 8, 2008 Posted May 8, 2008 I read recently that one of the step-up features of the highest-end 2008 Panasonic plasmas (850Z series) was "Digital Cinema Color, which increases the color gamut to 120% of the HDTV color space" (CNET.com). For me, this statement posed the question - what is the colour gamut of other plasma TVs and is it wide enough to make HDMI 1.3 a valuable feature? Putting aside the fact that there aren't currently any Deep Colour sources other than a few new HD camcorders, it's my understanding (and I could be very wrong) that plasma TVs generate colour using similar "phosphors" to CRTs. Since CRTs seem to be limited to the sRGB colour space, or 72% NTSC gamut, I assume (but I can find no proof) that plasma TVs are similarly limited. If this is true I imagine that the extended colour gamut offered by HDMI 1.3 cannot be used by current plasmas. Some questions for anyone who might know - Is HDMI 1.3 only useful on high-gamut displays? What is the colour gamut of current plasma TVs? When Deep Colour sources are displayed on a standard-gamut display through HDMI 1.3, are there artefacts?
spalmills Posted May 8, 2008 Posted May 8, 2008 I read recently that one of the step-up features of the highest-end 2008 Panasonic plasmas (850Z series) was "Digital Cinema Color, which increases the color gamut to 120% of the HDTV color space" (CNET.com). For me, this statement posed the question - what is the colour gamut of other plasma TVs and is it wide enough to make HDMI 1.3 a valuable feature?Putting aside the fact that there aren't currently any Deep Colour sources other than a few new HD camcorders, it's my understanding (and I could be very wrong) that plasma TVs generate colour using similar "phosphors" to CRTs. Since CRTs seem to be limited to the sRGB colour space, or 72% NTSC gamut, I assume (but I can find no proof) that plasma TVs are similarly limited. If this is true I imagine that the extended colour gamut offered by HDMI 1.3 cannot be used by current plasmas. Some questions for anyone who might know - Is HDMI 1.3 only useful on high-gamut displays? What is the colour gamut of current plasma TVs? When Deep Colour sources are displayed on a standard-gamut display through HDMI 1.3, are there artefacts? I think you might have to wait for Owen to answer this one. There may be others here to answer these questions but i have a strange feeling that Owen will thrive on this !!
alanh Posted May 8, 2008 Posted May 8, 2008 complectus, Essentially HDMI 1.3 will allow negative colour values of Red, green and blue. Please note that the total of 22.2% of Red + 70.1% Green and 7.7 % blue (which gives you the luminance value in HD signals) will always be positive because 0 is no light (Black). Negative individual values means that colours outside the range specified from the red green and blue primaries can be reproduced. If they cannot you will get a paler colour of the correct hue. If you have a laser or LED display it will be able to display the wider range of colours correctly. In general the CRT phosphors are the closest to the standard, however they are not making large screen CRTs anymore even for professional use. As far as signal sources go, the filters in the cameras must have colour filters with their peak colour sensitivities to the same hues as those of the phosphors. In existing colour cameras negative values as seen above are produced when very strong colours are in the scene. Since the transmission and recording systems use luminance and colour difference signals (eg Y, Pr, Pb), these negative values are carried. provided the colour difference signal are not excessive. HDMI 1.3 allows a greater range of bitst to keep those within the normal reproducable range of colours the same. Remember that all DVDs including Blue ray use colour difference signals. It is also used by component and HDMI signals. So for very strong colours particularly in blues and violets currently will display these colours either too blue or too red and also too pale. (You may only know this if you have seen the original colour very recently) Native colour is also called XV in Sony advertising AlanH
digitalj Posted May 8, 2008 Posted May 8, 2008 Guess that confirms that I should go for a laser TV when they are out and I can afford one.
Owen Posted May 8, 2008 Posted May 8, 2008 To provide a wider range of colours without introducing colour banding, you need more then 8bits per colour (24bits total). All domestic video sources use 8bit colour including BluRay which does not even support any more, so wide gamut colour is not an option in the foreseeable future. No point in a wide gamut display in a standard HD colour gamut world. Maybe when BluRay gets replaced by some future system wide gamut colour will become useful.
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