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1954 NTSC “Correct” Video.
A VK member wrote on his website :
“ Through years of eclectic research and dedication, Ed (Reitan) provided examples of early color video programs on DVD that duplicated the early color video signals enjoyed by those few who owned color television sets in 1954, 1955, and to the end of the 1950’s.” I believe this was in connection with a presentation at the 2007 annual Early Television Foundation convention of a CT-100 displaying “correct” NTSC color video as it was seen in 1954. I did not attend the convention and curious as to what program content was displayed on the CT-100 and wondering if that content is still available. |
Original NTSC would suggest following correctly the original color space and adhering to Illuminant C white. In addition separately the full chrominance resolution. This assumes later broadcast equipment up to the digital studio revolution and component 4:2:2 video became the norm.
I do not know how Ed would have claimed a DVD conveying the original NTSC broadcast format because the DVD itself normally would contain digitally compressed MPEG2 video, which I suppose would provide a signal that through a proper NTSC encoder could provide a higher luminance and chrominance resolution. And if the color space was accurately aimed at the original spec, that could be achieved as well. |
You must be referring to this:
https://www.earlytelevision.org/2007...on_reitan.html I think Ed's statement about this representing the actual color as seen on sets at the time was very wishful thinking. First of all, it wasn't videotape but a color kinescope film, which would not have exhibited accurate color even when brand new. Second, it was a Da Vinci restoration from scanning a badly faded color kinescope film, so the reproduction would be adjusted by eye rather than to a test pattern. But wait, you say, maybe the film had colorbars or something known? Well, a color kinescope film could not possibly reproduce the bright, pure colors of a test pattern. If the restoration were adjusted to do that, all the more subtle colors, like flesh tones, would be unacceptably off. So, the color in this demo may have been subjectively very good, but it would have had little accuracy in reproducing the original live viewing experience. |
Thank you both for your comments. So the best we can do is approximate?
I’m sure I’m not the only one who wonders what original 1954-55 NTSC color would like today on their calibrated Westy with 15GP22 or a CT-100. I was there to see original 1956, probably misadjusted color on my Uncle’s set and have visual memory of it. I’m amazed that the very early color tapes (kinescopes until tape came along) were not preserved by the broadcast engineers, or were they, but just squirreled away? What we have today is Milton Berle and Astaire from 1958. Eisenhower does not count, was not a television production. The link provided gives insight. Often thought about contacting DC Video. |
The ideal would be a NTSC tape played on its original type of machine with no adjustments beyond chroma amplitude and phase, and viewed on a 15GP22. Any additional stages in between (like decoding the NTSC into YCrCb for DVD and recoding as NTSC composite DVD player output) likely will (or in many cases definitely will) introduce modfications to match (or mismatch) modern TVs, monitors or computer screens.
A colorimetric analysis of the TK-41 spectral response shows that it was an excellent match to the original NTSC phosphors. This quickly went haywire as TV makers changed the white point and the phosphor primary colors themselves (particularly the green, but also the blue) in the quest for brighter pictures, and further when later camera makers tweaked the cameras to cater to the newer receivers and monitors. The train didn't get back on track until PAL standardized their cameras to match the modern phosphors. Then sRGB for computer stills and the color standards for HDTV also adopted the same primaries. This doesn't mean that camera makers necessarily did it by the book. Sony HD cameras in particular had a color rendition all their own, with particularly bright yellows - but the standardization meant that they could guarantee that all HDTVs would show the colors the way Sony intended. The Sony camera color may have been fudged to show the paler skin tones preferred in Japan, but I don't know for sure. I do know that we had to modify the matrix in the early Sony cameras to match the standard colors on the test chart (which the BTS cameras already did) when we were creating the subjective comparison test material for the U.S. HDTV format wars. |
With movies receiving a completely different color palette during remastering, I would not care for old TV programs. As long as skin is not blue, and streetlights have discernible red, yellow and green colors, it is good enough.
https://scontent.fsan1-2.fna.fbcdn.n...WQ&oe=678DA99F https://imageio.forbes.com/blogs-ima...png&width=1440 |
To me it's the historical value that outweighs the color accuracy.
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In a 1954 publication, Westinghouse claims the red phosphor in the 15GP22 had a “slow persistence causing fuzzy images”. Would this be one one of the reasons phosphors were changed? I know brightness as you say was an issue. |
I have done a careful job of producing still pictures that adhere to the original standard, including correct color matrixing and correct pre-filtering of the I
and Q channels. They start from Canon cmaera digital images processed to Adobhe RGB. These I display on my carefully adjusted CT-100. The results are extremely good, compared to the originals on a Adobe-compliant monitor. Its an entirely a bogus quest: I don't care what the original was, a proper 1990s Trinitron used as a display devi9ce for a CT-100 as tuner (RGB outputs to grid of a nonexistant 15GP22 converted to input for the monitor look great. This is true for any quality picture source. All the unmatchings don't make the colors look any less great. I watches last night's CFP game on my CT-100, about 3 feet from the screen, with the proper glasses to be in focus. It looked great. The only problem I actually noticed is that the goal posts are lacking in their yellow color. Now watching a Vikings-Seahawks game via NTSC is different matter: both uniforms are very neary pure Q. Its blur city. |
Watching the Vikings is a blur, this coming from a minnesotan.
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Edit: is it possible this comment refers to experimental tubes that preceded the production version of the 15GP22? I have read that some early prototype tubes had a red phosphor that required using a color filter over the face, making for a really dim picture; not sure about the persistence. |
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https://visions4netjournal.com/wp-co.../IMG_0671.jpeg Was it possible that Westinghouse had early access to prototype CRT’s? Yes, but in the article, they talk about production CRT’s and only the 15GP22 was in production at that time. I found an article in Television Digest, May, 1954 talking about new RGB phosphors used in the forthcoming RCA19 inch CRT(cancelled) principally to increase persistence time. |
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Hi to all,
Evolution of color CRT phosphors in Wikipedia article : "The red phosphor saw the most changes; it was originally manganese-activated zinc phosphate, then a silver-activated cadmium-zinc sulfide, then the europium(III) activated phosphors appeared; first in an yttrium vanadate matrix, then in yttrium oxide and currently in yttrium oxysulfide. The evolution of the phosphors was therefore (ordered by B-G-R):" Blue--------Green-----------Red ZnS:Ag – Zn2SiO4:Mn – Zn3(PO4)2:Mn ZnS:Ag – (Zn,Cd)S:Ag – (Zn,Cd)S:Ag ZnS:Ag – (Zn,Cd)S:Ag – YVO4:Eu3+ (1964–?) ZnS:Ag – (Zn,Cd)S:Cu,Al – Y2O2S:Eu3+ or Y2O3:Eu3+ ZnS:Ag – ZnS:Cu,Al or ZnS:Au,Cu,Al – Y2O2S:Eu3+ article is here: https://en.wikipedia.org/wiki/Phosphor Europium doping was a game changer finally allowing equivalent drive & beam currents on all 3 guns. developed by Sylvania if i recall correctly. June 1964 announcement by Sylvania in Electronics World : https://schematicsforfree.com/files/...TV%20Tubes.pdf for pure CRT enjoyment, read "The Cathode Ray Tube" by Peter A Keller, THE definitive publication on the subject. download pdf here, 330 pages, 50Mb : https://docs.ampnuts.ru/eevblog.docs...athode-ray.pdf Merry Christmas to all ! Best Regards jhalphen Paris/France Sylvania 1964 advert for ColorBright-85 CRT: |
That article is missing the original blue phosphor in the 15GP22, the NTSC specified one, which was less violet-blue than the ZnS:Ag. Can't recall the formula, off the top of my head, but it was used because they had trouble with copper contamination turning the blue sulfide phosphor green. The alternate got baked into the NTSC specs, then was replaced in tubes by ZnS:Ag at some point.
I have wondered for a long time if the blue change occurred in the middle of the 21AXP22 run time, or at the start, or later. The RCA triniscope had the more violet blue, and it seems likely that would have been the proposed NTSC spec if they hadn't run into the copper contamination problem. There is also some indication of a possible typo in some documents specifying the x,y color coordinates of the NTSC blue. Whether the final spec is the correct one or the typo isn't clear. By studying the RCA TV schematics from year to year, you can see the point at which they changed the color difference matrix to correct for the non-standard phosphors. Prior to that point, they used by-the-book color difference processing. Doing that with the more violet blue phosphor shifted yellows towards green. That, combined with the very cyan white point used in receivers and the sensitivity of the TK-41 dichroic filters to polarized light, caused a significant probability of blond hair being rendered greenish, while blues were rendered more violet. |
https://visions4netjournal.com/wp-co.../IMG_0718.jpeg
Quick blurb from Tele-Tech: Phosphors used in the cancelled RCA 19 inch color CRT. EDIT: Short persistence red…. Interestingly, RCA increased the diameter of the holes in the center of the shadow mask and gradually smaller diameter shadow mask holes out to the edges of the cancelled 19 inch color CRT in 1954. That along with the phosphor changes were said by observers to give a noticeably brighter image and fixed the persistence problem. |
The following article indicates the ZnS:Ag blue was used in the 21AXP22 from the beginning.
DEVELOPMENT OF A 21-INCH METAL-ENVELOPE COLOR KINESCOPE* By H. R. Seelen, H. C. Moodey, D. D. VanOrmer, and A. M. Morrell RCA Tube Division, Lancaster, Pa. Fink's telvision Engineering Handbook 1957, p. 1-35, has a list of phosphor coordinates with two blues: Blue silicate phosphor x=0.163, y=0.126 This must be the one meant to avoid copper contamination. It is much more toward cyan than the NTSC spec. Blue zinc sulfide x= 0.141, y= 0.082, which is exactly the NTSC spec. Modern blue zinc sulfide (sRGB, PAL, SMPTE, HDTV) is x=0.15, y=0.06 This has me wondering if 15GP22's have the sulfide and the copper contamination referred to earlier experimental tubes. Would have to put a spectrometer on some tubes to settle it. |
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