Have we had DVD colors wrong this whole time?

[jonnypoe]

Update to the FFmpeg command. It seems that colorspace does not convert the gamma, so I had to utilize both zscale and and colorspace to get the desired output:

-vf "zscale=min=fcc:m=fcc:tin=bt470m:t=bt709:pin=bt470m:p=bt470m:rin=tv:r=tv,colorspace=ispace=fcc:itrc=bt709:iprimaries=bt470m:irange=tv:fast=0:dither=fsb:wpadapt=bradford:all=bt709:range=tv"

[jonnypoe]

PCD with the Laserdiscs presents 100% better. These are much closer to what I remember from broadcast.

The DVD images still have issues. Way too much red (or not enough green) on the white point converted images.

Missed one key thing about fmtc_primaries() - It requires linear RGB as the input. Getting much better results now. Updated AviSynth script:

z_ConvertFormat(pixel_type="RGBPS", colorspace_op="fcc:470m:470m:limited=>rgb:linear:same:full")
fmtc_primaries(prims="470m", primd="709", wconv=true)
z_ConvertFormat(pixel_type="YUV444P16", colorspace_op="rgb:linear:709:full=>709:709:709:limited")

Posted some updated screenshots here: https://x.com/jonpoeschek/status/1928307054365790559

[Sunspark]

You have done great work here! Honestly, you should think about writing a small article or something and posting it somewhere since this wasn't trivial.

The only screenshot that can be compared before and after is the first one with the alien holding a padd. I can see that the screenshot on X is improved. It's not the same as the earlier one here.

For clarity, the MPV command for the copy operation, is it still functionally identical to your updated FFmpeg and AviSynth commands, or is there a difference?

What does "it does not work everywhere" refer to?

[flossy_cake]

MadVR does the white point conversion too - https://forum.doom9.org/showpost.php?p=2021128&postcount=130 (all my screenshot comparisons were taken with MadVR doing the conversion)

But it still doesn't get me any closer to knowing the correct gamut.... to my eyes DS9 season 1 looks fantastic at 470m and bad at 170m, but voyager season 1 looks bad to me at both 470m and 170m. Then randomly I was looking at season 4 of voyager iirc and that one seems to work well with 470m.

The 470m whitepoint is more magenta and that just makes any red push look even stronger, and season 1 of TNG already has a strong magenta push on many scenes.

I recall some commentary from the producers of the DVD release of the 1980s series of The Twilight Zone..they were talking about their analogue magnetic tape masters degrading over time. iirc they were surprised at how well those tapes held up in storage and that's why it still manages to look good even though all they had was these ancient tapes (and actually I think that tape has its own EOTF that looks amazing but that's my own personal taste in the same way people like mouldy cheese)

[flossy_cake]

Imagine how easy it would be to solve this issue if each episode had SMPTE colorbars at the end of the episode

Well we don't have that, but we do have these paramount logos at the end of TNG, DS9, Voyager DVDs

TNG S01E01 (https://imgsli.com/NDA1ODQ3)
DS9 S01E01 (https://imgsli.com/NDA1ODQ4)
TNG vs DS9 @ 170M (https://imgsli.com/NDA1ODUw)
TNG vs DS9 @ 470M (https://imgsli.com/NDA1ODUy)
Voyager S01E01 (https://imgsli.com/NDA1ODUz)
Voyager S01E01 vs S01E02 @ 170M (https://imgsli.com/NDA1ODU1) (because E02 has more pushed skintones vs E01)
Voyager S01E01 vs S01E02 @ 470M (https://imgsli.com/NDA1ODU2) (because E02 has more pushed skintones vs E01)

But I think ultimately we still can't make a definitive conclusion based on the logo if the logo was spliced in from a 170M source

edit: but I think these logos could still help us colourmatch all episodes within a season

[Sunspark]

I agree. It makes more sense that they added the logo after everything else was done, but who knows? I would be curious in what format the logo is provided during the production process. Is it a VCR they hit play on? Comparing to the PAL logo might be interesting whether it's the same or different.

[flossy_cake]

The DVD images still have issues. Way too much red (or not enough green) on the white point converted images.

That opens up another avenue of investigation - maybe that's why some seasons/episodes look pushed at 470M because something in the analogue mastering chain wasn't doing the 470M white point conversion.