Those are all the presets I have that I posted up there so far and I agree, all the old systems from that era look good with the composite/RF look
what is the address to locate your other presets ? once again thank you for it bud.
I’m not sure I understand. The CRT color profiles are all NTSC gamuts, which are wider than the sRGB gamut. Anything outside the sRGB gamut will be clipped and colors won’t display with the proper saturation, right? You need to use a gamut that’s as wide as NTSC, like rec 2020 or DCI-P3, AdobeRGB etc. To use one of these you need a wide gamut display, correct?
I think I’ve misunderstood you.
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There are no others, they’re all in the link I posted above in that shader post
Yeah so there are a number of things to unpack here. First let’s start with the matrices - I’m not sure how good your linear algebra is but essentially you can think of a matrix transforming one space into another i.e from your square dining room into your rectangular kitchen say or more pertinently from your rec.601colour space to rec. 709 colour space.
A correct transform matrix can never move a point inside a bounded region of a source space to outside the equivalent bounded region of a target space. As in if a blue is not being clipped in rec. 601 then the correct transform matrix will not make the equivalent blue clip in the target colour space.
There’s a slight kink in the simplicity because all these colour matrices transform into an intermediate colour space: CIE XYZ but we can ignore that here.
Ok so we could go on for pages about linear algebra so let’s stop there. Next ‘NTSC is a larger colour gamut at least in the blue direction than sRGB’ (to paraphrase) is that really true? NTSC is rec. 601 525 line colour space and sRGB is identical to rec. 709 colour space it just uses a different gamma curve. So did the engineers really make rec.709 smaller than rec.601 in blues? I’m not sure I’ve seen that written anywhere but I’m willing to be proved wrong.
Then onto the next thing your displays actual colour space Vs theoretical standard colour spaces. When a monitor says 95% DCI-P3 it’s only capable of displaying 95% of DCI-P3 colours and colours outside of that, the 5% will get clipped i.e be the same colour as one of the 95%. However what those 5% of colours are you don’t know and will change from monitor to monitor let alone, model to model or make to make.
Lastly if your TV is doing any kind of colour transforms as in brightness, contrast etc it could well push the colours outside of the colour space that your TV is capable of and so result in clipping.
Whether any of that has anything to do with what you’re seeing I don’t know but I hope it helps in finding the issue or making more sense of it.
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I am not sure that rec 601 is the color space for NTSC. It’s the standard for SD content, introduced in 1982. And yes, it’s practically identical to rec 709. NTSC is its own RGB color space, introduced in 1953 by the FCC.
Can you explain this diagram? This pretty clearly shows that NTSC is a wider gamut, no? Btw it’s mostly wider in greens as you can see:
https://www.eizo.com/library/basics/lcd_monitor_color_gamut/
Yes, but you cannot use a transform to display a wide color gamut on an sRGB display and not get a clipped and incorrect image, correct? It’s not the transform causing the clipping it’s the fact that the display can’t display all the colors you’re giving it.
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Lastly it’s all about of representation of the RGB (#,#,#) values. A calibrated dci-p3 for example represents and produces colors which weren’t present on the ordinary crt displays, giving a too saturated look, since primary colors, mostly green, have different chromatic.
In GDV, for example, a calibrated dci-p3 display when selecting the dci-p3 gamut should produce colors as seen on a sRGB limited display.
Selecting an appropriate color profile can bring colors closer to the desired crt look, but sRGB doesn’t differ too much from established crt phosphor specs.
It makes less sense to narrow the gamut on the sRGB calibrated/capable display, since the transformation is relative and will result in loss of saturation.
Reverse transformations to fake a wider gamut are a bit silly though and could give weird results. It’s best to just increase saturation a bit if someone wants more saturated colors.
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I think I’m on the same page.
sRGB is based on the most commonly used CRT phosphors but that doesn’t mean that sRGB covers all of NTSC. In fact, sRGB only covers about 72% of NTSC.
The important points for users:
-If you want to use a CRT phosphor gamut you should use a wide color gamut display, preferably rec2020 since it’s the only one that contains all of NTSC (afaik). You should also select the correct color space setting in the shader.
-If using a wide color gamut display the user should select the correct color space setting regardless of if they’re using a CRT phosphor gamut.
-If using an sRGB display one should just use phosphor gamut = 0 (in grade), or not use a CRT phosphor gamut.
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Yes I think its wrong. There’s no way that NTSC is nearly the same colour space as AdobeRGB. It doesn’t make sense does it? Why would the standards committee go down in colour gamut space - especially by that much. (EDIT: I now see why they went down in colour space: because no TV of the time could reproduce the colours in the 1953 NTSC colour space.)
All the images I see are much more like this, which makes far more sense to me:
Yes thats exactly right and what I’m saying. Whether you’d be able to really notice the difference between EBU (PAL) and 709 I’m not sure (my guess is that I doubt it with the naked eye - PAL vs NTSC (SMPTE-C) more so though)
I’m not sure where that NTSC colour space has come from but what I can say is that all the colour gamut transforms everybody is using (Grade, Guest and Sony Megatron) conform to the EBU (PAL/rec. 601 625 line) and SMPTE-C (NTSC/rec. 601 525 line) colour spaces. Just look and compare the numbers in matrices in the shaders vs those in the Khronos Groups pdf - they all match up and aren’t anything to do with this much larger NTSC colour gamut. I dont know 
EDIT: Ah-ha! I see where that larger colour gamut is coming from (from the Khronos Groups pdf):
14.5 NTSC 1953 color primaries The following chromaticity coordinates are defined in ITU-R BT.470-6 and SMPTE 170m as a reference to the legacy NTSC standard: Rx = 0.67 Ry = 0.33 Gx = 0.21 Gy = 0.71 Bx = 0.14 By = 0.08 Wx = 0.310 Wy = 0.316 (Illuminant C)
This is much larger - they were getting well ahead of themselves with this colour space and thats then why in the 1970’s everybody moved to the EBU and SMPTE-C colour spaces that the TV’s of the time could actually produce with their phosphors. Obviously 1980’s/1990’s consoles were way past the point of using the 1953 NTSC standard. Everything would look very wrong if we used that input colour gamut.
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That does appear to be what happened, though.
"The sRGB color gamut covers about 72% of the NTSC gamut."
This diagram shows the same thing:
and this one
https://color.viewsonic.com/explore/content/Color-gamut_205.html
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Yes I think it started with color spaces based mostly on pure theory and over time they became more empirical and based on what displays could actually do.
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The Reason why NTSC changed is right in the wiki article:
TL;DR early phosphors were crappy and so they decided to sacrifice saturation for brightness. NTSC was never very popular unlike SMPTE C
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Yes you’re right it did happen - I just edited my post - see “EDIT:” and was because they way over stretched back in 1953 (some might say the same is occuring with brightness in the rec.2020 spec). As I say in the edit no TV could actually display that and so the rec. 601 standard came out that brought everything back more inline with what could be done with the technology of the time. Its a colour gamut nobody was using much past 1970 it would seem.
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yep now we’re slightly back to theory with the rec2020 spec since displays might peak at 90% coverage.
Ok so the grade CRT gamuts and the GDV CRT gamuts are all within rec 601?
In short, does this part of the readme for guest-dr-venom need to be revised?
"
"
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You could argue its technically correct as in those EBU, SMPTE-C and Rec. 709 triangles on this diagram aren’t perfectly aligned but whether you’d notice the difference is arguable. EDIT: It does look like SMPTE-C is completely contained inside rec. 709 I’d have to look at the actual numbers.
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601 is completely within 709 afaik.
I’m confused, I think there must be something else going on.
Have you checked the x/y rgb values in the readme for guest-dr-venom to see if these are all within sRGB? Start at # CRT Color Profile #
It seems like the only ones (out of those in guest-dr-venom) that would be clipped would be the last two, the calibrated profile for Phillips CRT monitors and the calibrated profile for Sony Trinitron monitors, and it’s just the greens that are clipped…?
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sRGB is the same as rec. 709 in terms of colour primaries it only differs in the gamma curve that is applied (see the Khronos Group .pdf). I think this was because sRGB was aimed at the dektop with web pages vs 709 that was aimed at HDTV.
As for Guest-Dr-Venom I have no idea where those last two colour space matrices come from - I’m sure @guest can remember though? I’d be very interested.
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Yeah I’m just somewhat baffled by the readme, it suggests a wide color gamut is necessary but the first 3 specs are all contained within sRGB, it’s just the “calibrated” profiles that are slightly clipped, unless I’m not reading things right. This color stuff drives me nuts, lol.
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Color profile matrices were submitted by dr venom, other matrices were calculated from xy and color temperature specs using a calculation tool.
Color temperature matrices are relative to sRGB, but this shouldn’t matter too much since the xy transformation is neutral.
I would like to explain once more that the colorspace transformations are not absolute, but relative. They more or less produce xy primaries and color temperature shifts from what your calibration is and for best results a lut (for example) can be produced from you display’s icc profile to sRGB. DisplayCAL is a great tool for this.
Wider gamut of your monitor comes handy here as ‘gdv’ color profiles can be used with more accuracy.
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