Westinghouse K840CK15 Restoration

[etype2]

“ However, the use of high dynamic range mastering in itself does not tell you anything about whether the original tone curves of technicolor prints were emulated or not.”

Did additional research to address your comment. For what it’s worth, according to Warner Brothers: “Color processing was based on the colors from an original answer print kept at the Academy of Motion Picture Arts and Sciences.”

Didn’t know what an answer print was. Found two definitions:

Answer Print: The first print (combining picture and sound, if a sound picture), in release form, offered by the laboratory to the producer for acceptance. It is usually studied carefully to determine whether changes are required prior to printing the balance of the order.

An answer print is the first version of a given motion picture that is printed to film after color correction on an interpositive. It is also the first version of the movie printed to film with the sound properly synced to the picture.

Warner Brothers states that everything possible was done to maintain the integrity of the original print including leaving the rough edges of makeup applications on the actors. This could have been smoothed out of the 4K master. The only thing they edited out was suspension wires which appeared in three restored scenes.

To your comment about projectors, we are fortunate to have the best of both worlds, a Sony 4K projector spec. BT 2020 calibrated to ISF standards for REC.709 HD and 4K HDR with 130 inch screen. For the theatrical experience the projector is the way to go, but it can’t display full HDR due to brightness limitations of the lamp and agree with you as to your comments. I prefer watching HDR on OLED. The only way to describe it is it’s like seeing the Trinitron for the first time in 1968 or the first time seeing HD. It’s even better than that. Netflix is currently showing a series “Bridgerton”. it was shot in RAW with RED cinema cameras. Stunning! Currently one needs to spend 35K and up for laser projectors that can display full HDR as specified by the UHD Alliance.

[etype2]

Back to 15GP22 color performance. 67 year old technology in today’s world.

Screenshots from Kiss Me Kate shot in RAW processed in TIFF. Sorry, I can’t get enough of seeing new details not seen with Jpeg and I hope you like them. I’m going to remove all the jpeg’s on my site, replace them with Tiff. :-)

EDIT: A fast internet connection will help.

https://visions4netjournal.com/wp-co...BC46F5EC7.tiff

https://visions4netjournal.com/wp-co...7655E3545.tiff

https://visions4netjournal.com/wp-co...0BB38067A.tiff

https://visions4netjournal.com/wp-co...4F08B9EC5.tiff

[etype2]

I found this researching early Quad recorders.

Per Ed Reitan: * During the restoration of the Eisenhower and Astaire tapes: * “I use the terminology "RCA Labs Color" for the format of the original Eisenhower, Astaire, and other NBC color tapes used on the modified Ampex machines * (monochrome to color) * at Burbank from early 1958 through at least April 1959," he said.

“ I suggest the term 'RCA Broadcast Color' for the format of the tapes produced by the RCA TRT-1AC, the first color recorder produced by RCA Broadcast of Camden, N.J., and also used by NBC at Burbank starting in April, 1958," Reitan advised. “

" These are distinguished from tapes made to the later “Low Band Color“ standard later promulgated by SMPTE."

His comments suggest something other than 1953 NTSC color, but better than SMPTE-C. I wonder what color metrics were used in the modified VTR’s and later in the production RCA TRT-1AC?

Starting in June, 1955 with the introduction of the RCA CTC-4 the WCG of the 15GP22 and 21CT55 were changed to less saturated colors according to comments read in this forum.

* Added by author.

15GP22 used in our restored Westinghouse H840CK15.

EDIT: To add to the question, I’ve read the “ RCA Labs heterodyne color” as used in the above VTR’s was low band color and replaced by high band color in the 70’s?

[old_tv_nut]

The video tape recorder specs have nothing to do with the colorimetry. They refer to the center frequency and deviation of the FM video carrier on the tape.

Quad tape takes the entire NTSC composite signal including the chroma subcarrier and modulates an FM carrier for recording on the tape. There was experimentation with the FM frequencies used, settling on the original "low band" spec. This had some problems with full amplitude high luminance colors, particularly yellows. Even later, the frequency response of the recording heads was improved and the FM modulation frequency increased to create the "high-band" quad specification.

Home systems such as VHS modulate only the luminance on an FM carrier, and record the chroma signal as a lower frequency "color under" subcarrier that is recorded on the tape the same way an audio signal might be, except that its frequency range is in the hundreds of kilohertz. In this case, The FM luminance carrier acts as the bias frequency for the chroma the same way that a supersonic bias waveform is used when recording audio tape.

[etype2]

Fair enough, you have explained low and high band to a point. I thought VTR’s had to be engineered for a given color spec. ie, Pal, SECAM, well these are formats, I understand, bad example. I think you know what I mean, but you’r saying those early modded Quads recorded full 1953 NTSC color?

That being the case and not an engineer, was it a case that early television shows were broadcast with the full 1953 NTSC color signal but the televisions from 1955 and after couldn’t reproduce the complete signal? And SMPTE-C came in about 1968 and shows were being monitored on Conrac monitors with SMPTE-C color space? I’m not understanding.

What was meant by Ed’s comments about “RCA LABS color and RCA Broadcast Color” ?

[jhalphen]

Hi to all,

Hi Etype2, old_tv_nut,

Early color Quad machines :
"RCA LABS color and RCA Broadcast Color"

The full story is here :
http://www.quadvideotapegroup.com/re...washington-dc/

and here :
https://www.provideocoalition.com/re...ision-history/

Early experiments by RCA to record color on 2" Quad was done by modifying an Ampex VRX-1000 series machine which was then only B&W.
The experiment used a mix of heterodyning the color signal & optimizing the pre-emphasis of the FM recording modulator.
The machine worked but was a totally non-standard setup as the standard had not been written yet.

Later on, the FM recording frequencies and pre-emphasis/de-emphasis parameters became a standard which all brands of Quad machines had to respect to ensure tape interchangeability.

Now some very early color recordings of historical value were made with the experimental RCA Quad color specs.

One of Ed Reitan's significant achievements was to modify an Ampex standard color VTR to replay once & transfer the historical content to a modern digital format.

This was a difficult endeavour, electronically modifying a 60 year old machine to work with a +/- unknown experimental color format.
An Ampex AVR-1 was used. A set of spare plug-in boards were modified to comply with the RCA experimental standard.

After the transfers, the VTR was returned to standard configuration.

Ed Reitan and other team members of the project received an Emmy Award for their achievement.

Best Regards
jhalphen
Paris/France

[old_tv_nut]

Originally Posted by etype2

Fair enough, you have explained low and high band to a point. I thought VTR’s had to be engineered for a given color spec. ie, Pal, SECAM, well these are formats, I understand, bad example. I think you know what I mean, but you’r saying those early modded Quads recorded full 1953 NTSC color?

That being the case and not an engineer, was it a case that early television shows were broadcast with the full 1953 NTSC color signal but the televisions from 1955 and after couldn’t reproduce the complete signal? And SMPTE-C came in about 1968 and shows were being monitored on Conrac monitors with SMPTE-C color space? I’m not understanding.

What was meant by Ed’s comments about “RCA LABS color and RCA Broadcast Color” ?

Details of the VTR's signal format have to be set according to the particular system's vertical and horizontal scanning rates and color subcarrier frequency. This has nothing to do with the primary colors, which are determined back at the camera before modulating onto the NTSC or PAL color subcarrier.

So, yes, these early tapes were made with TK-41 camera chains that had NTSC color.

You are correct that NTSC always used NTSC coding for the whole duration of analog broadcasting. Also that the receivers began to have non-NTSC phosphors around 1957. Also correct that SMPTE C phosphors are not NTSC. Receiver makers at first made no electrical compensation for the color of the phosphors, only for their improved efficiency (by changing the R,G,B drive levels to keep their chosen white point, which, by the way, was not NTSC, but much more cyanish).

After some years, the TV makers made adjustments to the color difference demodulators to compensate approximately for the new phosphors. SMPTE also standardized a similar electrical matrix for SMPTE C phosphor monitors that could be switched on and off. These changes were not ideal because they are applied to signals that have been gamma corrected, so some colors get overcorrected (especially bright reds) and others get undercorrected. The proper place to correct for different primary colors is at the camera before gamma correction, so the effects are linear. This is what PAL did to standardize on the new phosphors, and what programs like Photoshop do. In the case of Photoshop, since it is dealing with files that have the gamma correction baked in, they undo the gamma correction from the camera, make the color adjustment, and redo the gamma correction for the monitor.

Note that NONE of the above affects what equations are used to form the luminance and color difference signals and hence subcarrier signal in NTSC or PAL. In fact, PAL simply adopted the same equations for forming the color subcarrier as NTSC, even though the original R,G,B signals from the camera were modified for new phosphors.

So, when the composite signal (luma + subcarrier) gets to the VTR, it knows nothing about what primary colors the camera was matrixed for. It just records and reproduces what it is given.

When TK-41s began to be displaced by Plumbicon cameras, linear matrixing for different phosphors became possible (too complex and drift-prone for the all-tube TK-41s). So, camera designers modified the color-splitting optics for best efficiency and signal-to-noise, and then used a linear matrix to produce the "right" R, G, B for NTSC or PAL. But, since no color optics is perfectly matched to the human visual system, the camera's interpretation of the scene could also be fudged for best-looking pictures on the SMPTE C or EBU modern monitors. In PAL, this would be close to the theoretically correct matrix, since PAL receivers had fixed demodulator specs (borrowed from NTSC) and known modern phosphors. In NTSC, however, the TV makers had modified the circuitry for an approximate correction, and the camera makers obviously couldn't broadcast multiple versions to match multiple TV designs. So, camera designers did the next best thing, and made the cameras look best on SMPTE C monitors. BUT, the circuits following the gamma correction in the camera were still precisely NTSC.

[etype2]

I see said the blind man.

Thank you gentlemen, the both of you and also Electronic M.

Very well explained and clears up my misconceptions. Moving forward.

About Ed Reitan. I never met him, but spoke to him on the phone. I think you all know of his contributions to our hobby and was sad to learn of his passing. We were lucky to “win” a CTC-7 Worthington at an ETF auction. It belonged to the estate of Ed Reitan. RIP. Was thrilled to be the custodian and set about a full restoration with Mike Doyle. I liked the provenance of the set and it’s design.

Created a tribute to Ed on this website. https://visions4magazine.com/2017/04...rst-blog-post/ It’s hosted for free and loaded with advertisements. I apologize for that. You can see a sneak preview of “An Evening With Fred Astaire” displayed on a 21CT55, with the goal of displaying the Special on Ed’s CTC-7. Both the Worthington and Special were introduced in 1958. We have since accomplished this but I can’t show it to you because Mr. Astaire’s widow will come down hard. She is strongly opposed to having the Special on the internet. Many thanks to the generous donor who shall be nameless.

[etype2]

“In the case of Photoshop, since it is dealing with files that have the gamma correction baked in, they undo the gamma correction from the camera, make the color adjustment, and redo the gamma correction for the monitor”.

Is there a special program to do this or is this built in to Photoshop? Does Photoshop tell you the values of absolute black or white or green etc; expressed numerically? And I need a matched monitor?

[old_tv_nut]

Originally Posted by etype2

“In the case of Photoshop, since it is dealing with files that have the gamma correction baked in, they undo the gamma correction from the camera, make the color adjustment, and redo the gamma correction for the monitor”.

Is there a special program to do this or is this built in to Photoshop? Does Photoshop tell you the values of absolute black or white or green etc; expressed numerically? And I need a matched monitor?

Built in. It's all part of a color-managed workflow, where each device is profiled/calibrated and photoshop knows the info. In other words, your computer should have a profile for your monitor (a generic one like sRGB, or a factory-supplied default, or a profile measured with a calibration instrument); your camera records things in a particular color space like sRGB or as a raw file that has known characteristics from the maker; your printer/paper combination can have a profile, (or Photoshop may output in a standard space while the manufacturer's printer driver converts the color to ink values). Photoshop converts everything into its own working space for manipulation and then renders it in the monitor space for viewing and the printer/paper space for printing.

[old_tv_nut]

Photoshop tells you the RGB values in its working color space (sRGB, ProPhoto, or whatever you have chosen) which includes a non-linear transfer function, for example, the "gamma correction" in sRGB. It does not tell you linear amounts of red, green and blue light primary colors. Although not strictly logarithmic (like photographic F-stops), it is similar, and makes for useful, readable histograms.

Photoshop is aimed at the needs of photographers and artists, not scientists. Some operations in Photoshop may actually work in linear space (the conversion from one set of primaries to a different set, for exmple) but this is buried in the middle of the process and is not displayed to the user.

Another example of something Photoshop/Camera Raw and Lightroom do without mentioning it is to apply an S-curve transfer function to images. This base curve can be modified by the contrast adjustment. It is essential to getting pleasing photos (as Kodak discovered in the late 1800s), but Photoshop never tells the user what the curve actually looks like. This curve is applied before any Curves adjustment made by the user, so even if you leave the Curves adjustment set to linear, the overall process has an S-curve built in.

There are many other details to photo-editing software that are designed to make the best looking and therefore not scientifically accurate photos, just as was the case with film.

The S-curve both compensates for the reduced contrast impression of the eye when viewing a print as compared to the original scene, and also makes it possible to use a display device or print process with limited contrast range to display a scene that originally had a much higher contrast range, without hard clipping of highlights and shadows.

[Electronic M]

Originally Posted by etype2

Starting in June, 1955 with the introduction of the RCA CTC-4 the WCG of the 15GP22 and 21CT55 were changed to less saturated colors according to comments read in this forum.

* Added by author.

15GP22 used in our restored Westinghouse H840CK15.

Something to note: the CTC-4 didn't reduce color gamut. It reduced chroma video bandwidth. Bandwidth reduction reduces the amount of color detail (ie a CTC2 would color smaller dots of a fireworks display than a CTC-4 could), but doesn't affect the color gamut. The color gamut is affected by the phosphors and the signal matrixing equations in the TV. The CTC-4 used a 21AXP22 and some of those sets have the early AXPs that are said to have the correct NTSC phosphor. A CTC-4 may have less color detail and a redesigned demodulator circuit (to reduce parts count and make the set more affordable), but I have to believe RCA was still shooting for NTSC correct matrixing.

One thing to consider: 15GP22 based sets have a coarser phosphor dot pattern relative to screen size than 21AXP22 sets do so the to an extent the increased detail a CT-100s demodulator gives relative to a CTC-4 is atleast partially wasted in the CT-100 due to its coarse dot structure.
Probably the best set for seeing the full quality of early NTSC would be a 21CT55 or a CBS 205 which had the wideband chroma, fine phosphor dot pitch and NTSC phosphored CRTs.

[etype2]

” There are many other details to photo-editing software that are designed to make the best looking and therefore not scientifically accurate photos, just as was the case with film. ”

Looks like I’ll be getting a monitor or laptop for Photoshop. Don’t have Photoshop yet. For iPad they rent it, for PC or Mac they sell it. I’ve read that color professionals and artists prefer Mac. I just have to make sure of the color profiles available with the devices. Photoshop has always intimidated me. I asked about numeric color values because I recall seeing a PS screenshot with some color and a number or value. So I’m here thinking if you go to a CSS color chart, look up the color values, one could dial them in with PS.

EDIT: I’ve had software, not PS that gives the CSS color value when clicked on, so it could easily be reproduced.

Will be posting a screenshot or two shortly to keep this thread on topic.

[etype2]

” Probably the best set for seeing the full quality of early NTSC would be a 21CT55 or a CBS 205 which had the wideband chroma, fine phosphor dot pitch and NTSC phosphored CRTs.”

Having both of these sets restored, (not the CBS 205) I agree that that the dot structure is more visible on a 15GP22. The phosphor application on my 15GP22 is uneven at the edges and can be seen in my shots. I guess they hadn’t perfected the application process in the first CRT.

[dtvmcdonald]

I'd sure love to see a 21CT55 that has been restored and tuned to perfection.
In fact I don't recall seeing any 21 inch roundie at the ETF with a
picture I would call better than poor. The CT-100 and Westy there have, at times, been in first rate tune.

In my opinion the dot pitch on the 15GP22 is adequate for a set with a luminance trap at 3.6 MHz.