"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Why is video inverted for transmission?
Started by ●September 19, 2007
Reply by ●September 20, 20072007-09-20
Reply by ●September 20, 20072007-09-20
"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Reply by ●September 20, 20072007-09-20
"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Reply by ●September 20, 20072007-09-20
"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Reply by ●September 20, 20072007-09-20
"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Reply by ●September 20, 20072007-09-20
"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Reply by ●September 20, 20072007-09-20
"Mark" <makolber@yahoo.com> wrote in message news:1190316861.873947.152340@r29g2000hsg.googlegroups.com...> Some distant day in the US is Feb 17, 2009.Looks like it's really going to happen this time too -- all the analog TV boxes now have the, "Warning! This TV will stop receiving over-the-air broadcast in 2009!" stickers on them these days.
Reply by ●September 20, 20072007-09-20
"glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message news:jLmdnUPa1KJRXm_bnZ2dnUVZ_gqdnZ2d@comcast.com...> Since gamma correction is done differently for color, the > resulting luminance isn't exactly correct. Given that, > I would have to agree that some chrominance information is > in the luminance signal, but it is relatively small.The original definitions of the three signals in the NTSC standard were as follows (they've since changed slightly, to harmonize with the European-standard "U" and "V" signals in place of the original "I" and "Q"): Y = 0.587G + 0.114B + 0.299R I = -0.274G - 0.321B + 0.596R Q = -0.532G + 0.311B + 0.211R Now, it so happens that with this definition, the "Y" signal is something that works very well for a visually- acceptable luminance-only ("black and white") image, but which of these three would you say carries the most or the least color information? You can't recover the needed RGB signals without all three. Bob M.
Reply by ●September 20, 20072007-09-20
Joel Kolstad wrote:> "Mark" <makolber@yahoo.com> wrote in message > news:1190316861.873947.152340@r29g2000hsg.googlegroups.com... > >>Some distant day in the US is Feb 17, 2009. > > > Looks like it's really going to happen this time too -- all the analog TV > boxes now have the, "Warning! This TV will stop receiving over-the-air > broadcast in 2009!" stickers on them these days. >Yeah but it has been postponed how many times now? I guess this deadline is more serious though as some spectra have supposedly been auctioned off. And at least out here no converters in sight. Oh man, I do not want to be in the shoes of a local politician on Feb-18, 2009. -- Regards, Joerg http://www.analogconsultants.com
Reply by ●September 20, 20072007-09-20
Bob Myers wrote: (snip)> The original definitions of the three signals in the NTSC > standard were as follows (they've since changed slightly, > to harmonize with the European-standard "U" and "V" > signals in place of the original "I" and "Q"):> Y = 0.587G + 0.114B + 0.299R > I = -0.274G - 0.321B + 0.596R > Q = -0.532G + 0.311B + 0.211R> Now, it so happens that with this definition, the "Y" > signal is something that works very well for a visually- > acceptable luminance-only ("black and white") image, > but which of these three would you say carries the > most or the least color information? You can't > recover the needed RGB signals without all three.No, you can't recover RGB without all three. Yes, Y is a good "black and white" image signal, but it isn't the correct one. The R, G, and B in the equations above have been gamma corrected. If R=G=B then Y is appropriately gamma corrected, otherwise it isn't the exact gamma corrected Y. (Hint: (X+Y)**2 is not equal to X**2+Y**2.) Since RGB has three degrees of freedom, and Y has one (luminance) that leaves two for chrominance. That is, chrominance is the amount of information that, when combined with luminance gives the appropriate color signal. (I believe it is usual to use R' G' B' and R G B gamma corrected and uncorrected signals, though I forget which one gets the prime and which doesn't.) -- glen
