#31
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I read your interesting discussions about the topic. I want to clarify that my comments were referring to the systems at the beginning, and no subsequent improvements. performed over time.
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#32
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PAL & SECAM were developed by learning the lessons that NTSC provided. They tackle similar problems in different ways. The problem is that over the years so much ground has been covered with the improvement of the various systems, that its hard to really look back and see what the original problems were. For example, you mentioned saturation problems. The question is, were they really problems with the NTSC standard, or were they problems with the vacuum tube (valve) technology of the time? If so, did those problems supposedly corrected by PAL & SECAM suddenly disappear once the technology shifted to solid state? If so, then it wasn't a problem in the standard, but in the implementation. I'd be curious though to read more about the problems you describe. I know that especially in the early days no one had a good idea how to correctly setup color systems. ABC TV here in the states didn't even use vectorscopes for color setup. All of the color setup and testing procedures were developed over a long period of time, and often through experimentation. David |
#33
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Going back on topic to the color variations in NTSC. I think I might have found at least a source that may answer some of our questions about early NTSC. The BBC launched a trial of NTSC on their 405line system. Although I haven't had a chance to read all the way through, they are likely to give the good and the bad about NTSC in their report. I post it here for all to consider:
http://www.bbc.co.uk/rd/pubs/archive...nograph_18.pdf As I said. I don't know if the answer is there, I haven't read it all the way through yet (its pretty technical). But, it should be a good read for this subject. David Last edited by dtuomi; 12-16-2008 at 08:44 PM. Reason: Spelling |
#34
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the news that I reported here are from technical reports on the comparison between different systems. not personal opinions.
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#35
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David |
Audiokarma |
#36
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Thanks! i have not seen a copy before - now to read. read, read... |
#37
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Zenith
Zenith also made tv specifically made for Pal B/G 625 lines. This is my Zenith hybrid tv. Not modified nor "assembled in Italy". Just a Zenith Pal tv.
In my opinion Secam tends to develop a kind of bluish smear on some color areas and this is noticeable with my old hybrid french tvs as with the newest ones. I once had the chance to watch a football match broadcasted in NTSC M with a RCA solid state 19" tv and the colors were simply superb! I never saw anything similar on any Pal tv. I don't think matter of color accuracy is so important. I think is what please the most the viewer's eyes is what really counts! Color perception varies from one subject to another. I met people who thought they had perfect pictures on their tvs which were instead quite far from color perfection (reddish or bluish or greenish whites, colored blacks etc...). Isn't pleasing watching an old english film and see red telephone cabins displayed in vivid red? Not very similar to reality but undoubtedly nice... My two cents... |
#38
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yes, but remember that this was not to compare the various systems after the changes made over time. I was referring to the systems compared to their first debut on the market, ntsc was especially infamous for the instability of the stage, the SECAM is famous for the color red tomato, the pal had no major problems as was the synthesis of earlier systems with the elimination of these defects first.
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#39
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So I've not yet found the exact problems you describe. David Last edited by dtuomi; 12-19-2008 at 08:00 PM. Reason: I talk too much |
#40
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One thing I notice after 39 years of watching NTSC color:
When my parents got our RCA CTC-38 (1969), the color was usually good at one "right" hue (phase) setting, yet it was not very uncommon (especially on videotaped network programming) for the phase to be far off the mark (green or purple faces, blue grass). Sometimes the local station would super a notice "technical difficulties" at the bottom. I understand this was because the NTSC reference signal ("back porch", "color burst") could not be transmitted with the picture on the microwave links then in use by networks (please, someone, tell me WHY this was so, if they can send a chartreuse dress image on the link, they can send the burst, can't they ?). By about 1980, these "off-phase" events became very rare, so an NTSC-country TV viewer can set the "TINT" function just once and leave it alone. (this is now usually an item on the on-screen-display, like the "BRIGHT" or "CONTRAST" functions I assume are on the OSD menus of PAL and SECAM sets as well as NTSC) I can only think of three reasons I adjust the hue. (1) one of my VCRs has it's own phase, red shows a little orange if I do not adjust it back to red. (2) one low-power station, on a near-zero budget (same as the old VCR). (3) My daughter is quite amused when I change Bob the Tomato into a giant grape! |
Audiokarma |
#41
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#42
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For a short time, a signal called VIR (vertical interval reference) was implemented. The idea was that this auxiliary burst would be inserted at the studio and not adjusted or replaced along the network. Some TV sets (General Electric in particular) used the VIR to make automatic color adjustments. However, broadcasters discovered that they could use the VIR to adjust the signal and even automatically compensate any transmitter shortcomings. At that point, the VIR was being adjusted and no longer represented the original studio signal. Eventually, the industry gave up on the whole idea. Improvements were made in the networks over the years. At one time, the networks adopted atomic clocks to set the burst frequency, and the local stations then locked to that. Later, when frame synchronizers became available, the local stations could re-sync all incoming signals to their local reference. Another big improvment was simply the move to solid state gear, which could go much longer than tube gear without drifting out of specification. These days, with much video being originated in digital components, or at least converted to digital before going over the network, there are fewer points at which it is critical to carry the burst properly. |
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