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Recent experience adjusting color temps on my Panny has had me wondering. I'm guessing this might be a stupid question so please forgive me if it sounds too obvious, but if the panel's color decoder is responsible for rendering colors on the A/V input (and showing its own unique characteristics a la red push, etc.), does the panel's color decoder also have a play on the component input, or does the source provide all color information (hence the three separate component cables)? I realize that each input needs its own set of adjustments which seems on the surface to suggest the component signal source does all color decoding itself, but I'm just trying to understand this $3.5K piece of equipment a little better.


Thanks!

- J.T.
 

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Component video bypasses the display's comb filter and color decoder and is converted directly to RGB.


S-Video bypasses the displays comb filter, but still passes though the color decoder.


Composite goes through both the comb filter and color decoder.


Since the Panny generally has a superior comb filter than VCRs and LD players, using the composite video output on these devices usually produces a better picture than the S-Video output. This is not the case for DVD players because the S-Video signal is created directly from the component signal, not from a composite signal run through a comb filter.


-Steve
 

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"Color decoder" is a bit more complex than that. There are really three functions involved here:


a) separating the color sub-carrier (a 3.58mhz signal modulated by two color-difference signals) from the luminance signal (a signal of 4.5 mhz bandwidth containing all the black & white information)


b) demodulating the color sub-carrier to extract the two color difference signals (Y-R aka Pr and Y-B aka Pb) and


c) Mathematically matrixing these two signals along with the luminance signal (Y) to produce the R, G and B signals that drive the actual display.


The comb filter separates the color subcarrier from the luminance signal. It is only needed for composite, because with S-video, the subcarrier is on a separate wire.


The demodulator is needed for both composite and S-video, but not component.


The theoretical advantage of s-video is a kinda chicken-vs-egg thing, since most s-video signals are created in the first place by running a composite signal through a filter to separate the color subcarrier. This provided a dramatically better picture back in the days when a laserdisc player with a decent comb filter was feeding a TV set with none. Today, you have to decide where the best comb filter is and configure your system to make use of it.


Composite and S-video signals have to fit the specs of the NTSC or PAL format, which means that the color difference signals have VERY limited bandwidth. Most of the picture detail exists only in black & white. Component is potentially much superior these because there is no inherent limitation on the bandwidth of the color difference signals (or of the luminance component, for that matter.) That's why DVDs normally yield a much more detailed picture via component and why component supports HD signals.


However, even component signals need to pass through some sort of matrix to convert them to RGB, and if the values here aren't correct, color balance will be off. In fact, red push is usually created, whether through poor design or on purpose, in the matrix, so a component input in no way guarantees an absence of red push. That is why, again in theory, it is better to run HD into a monitor via an RGB connection, since an ATSC decoder generates RGB directly, and has no need to deal with color-difference components.
 
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