[css-color-4] Hyphens in colorspaces

[jstblck]

Since the modified version of DCI-P3 in CSS 4 is the same as the version already in use by Apple, would it not make more sense to use the same name, ie display-p3 instead of image-p3?

From CSS 4:

It uses the same primary chromaticities as DCI-P3, but with a D65 whitepoint and the same transfer curve as sRGB.

From Apple:

This color space uses the DCI P3 primaries, a D65 white point, and the same gamma curve as the sRGB color space.

'Display P3' is also used on some forums and in places on Wikipedia with the above meaning.

Also, for consistency, should Adobe RGB (1998) be named adobe-rgb-98 or preferably just adobe-rgb, and ProPhoto RGB named prophoto-rgb?

This would make the naming scheme the common name (but with a hyphen replacing any spaces) with, if necessary, the version (such as the year for Adobe RGB) as a hyphen-separated suffix.

[svgeesus]

Thanks for your comments.

The P3 colorspace was introduced into CSS Color at the request of Apple. We originally called it DCI P3 because that was what we thought it was. As more information emerged (different whitepoint, different viewing conditions and transfer curve) the naming was discussed in the CSS WG. image-p3 is the name that emerged as the favourite. Representatives from Apple were involved in those discussions.

Adobe RGB (1998) is the official, trademarked, name of the Adobe colorspace. For licensing, trademark and copyright reasons, that phrase can't be used to describe the colorspace used in CSS. (I know). Nor can we use the phrase Adobe which would be a registered trademark infringement.

By the way there were several variants of the Adobe colorspace, so the 1998 specifier is an important part. This is why CSS has a colorspace called a98rgb.

It might indeed be more consistent to write a98-rgb and also prophoto-rgb which would also be easier to read.

[grorg]

FWIW, I prefer the name display-p3

[svgeesus]

Well, ok then! Lets get the CSSWG to change that,

[astearns]

We switched from display-p3 to image-p3 in 2016, but I can’t actually find the discussion behind making the change 619c1fd

[jstblck]

Thank you for your reply @svgeesus.

The P3 colorspace was introduced into CSS Color at the request of Apple. We originally called it DCI P3 because that was what we thought it was. As more information emerged (different whitepoint, different viewing conditions and transfer curve) the naming was discussed in the CSS WG. image-p3 is the name that emerged as the favourite. Representatives from Apple were involved in those discussions.

I'm suprised Apple didn't want it to be called display-p3 instead of image-p3.

Adobe RGB (1998) is the official, trademarked, name of the Adobe colorspace. For licensing, trademark and copyright reasons, that phrase can't be used to describe the colorspace used in CSS. (I know). Nor can we use the phrase Adobe which would be a registered trademark infringement.

By the way there were several variants of the Adobe colorspace, so the 1998 specifier is an important part. This is why CSS has a colorspace called a98rgb.

It might indeed be more consistent to write a98-rgb and also prophoto-rgb which would also be easier to read.

It's a shame adobe can't be used. Would a-rgb-98 be better? That seems more consistent but also easy to read and wright.

I just think the built-in profiles need a naming scheme. Ideally, one that's consistent, easy-to-parse, and scaleable.

[css-meeting-bot]

The CSS Working Group just discussed Predefined colorspaces (renaming image-p3 to display-p3), and agreed to the following:

• RESOLVED: Take what we're calling image-p3 in our spec and rename it to display-p3

The full IRC log of that discussion

<dael> Topic: Predefined colorspaces (renaming image-p3 to display-p3)
<dael> github: https://github.com//issues/4056#issuecomment-505993145
<chris> I looked into the edit history, there were a number of changes drom dci-p3 to where we are now. Rik was the main contributor; there was discussion on the commits. See for example https://github.com//pull/557/commits/644c4c49b86d97bb59bf74e533bdfbe339f3d176
<TabAtkins> s/TabAtkins/tantek/
<dael> chris: Looked at htis. When originally put in spec confusion between dcip3 and what apple used. I originally called it dcip3 and that was wrong for many reasons
<dael> chris: Thought had resolution, but can't find. Went through edit history and it went through name changes. I'm happy changing to to what everyone knows it as
<dael> dino: My memory is not great. At some point I posted the profile for it given the idea it can be linked form the spec. I'm in favor of display-p3. Also willing to add another named to dci-p3 but I don't think there's a need
<dael> chris: I don't think there is. dci-p3 has strange greenish white and designed for use in digital cinema. Not appropriate for web
<dael> dino: That's the main driver for Apple creating what we call display-p3
<dael> tantek: You said because it's designed for dark env it's not appropriate for web
<dael> dino: Pitch black rooms
<dael> tantek: People do use the web in black rooms
<dael> dino: This is just hte convenience method. You can get the same result using display-p3. It just happens to have been calibrated for different env.
<dael> tantek: Is that calibration not useful when looking at web in the dark?
<dael> dino: If you're writing to be used in something like a cinema sure
<dael> astearns: THt's an argument to add dci-p3, but this is about what do we call the thing that we know is not dci-p3 and we want to support it
<dael> AmeliaBR: Adding sep profile can defer until demand. There is demand to match the thing Apple does. If the definition is match Apple then we should match the name unless there's trademark reasons
<tantek> s/black rooms/dark rooms
<tantek> s/just hte/just the
<dael> dino: Nothing apple specific about this other than we gave it a name. That's why I posted the file. There's nothing secret or protected about this
<dael> chris: Given that I would like to call for resolution
<dael> astearns: I could not find reason why we changed from display-p3 to image-p3. There's some discussion about how web isn't only for displayed, but not terribly compelling.
<dael> astearns: Prop: Take what we're calling image-p3 in our spec and rename it to display-p3
<dael> astearns: Objections?
<dael> RESOLVED: Take what we're calling image-p3 in our spec and rename it to display-p3
<dael> dino: Anything we can do in CSS to stop people from using their phone in a cinema?
<dael> astearns: Happy to follow the incubation process

[svgeesus]

In terms of consistent hyphenation: everyone writes srgb (well, they write sRGB) and s-rgb would be odd.

On the other hand prophotorgb is a bit long and hard to read, prophoto-rgb might be an improvement. And if we did that, then a98-rgb would also be reasonable.

Leaving issue open for further discussion on those.

[svgeesus]

I'm suprised Apple didn't want it to be called display-p3 instead of image-p3.

We were unable to find an actual resolution to use image-p3 and indeed, on the call today Apple expressed a preference for display-p3 as indeed did everyone else who had an opinion. So I just made that change.

[svgeesus]

I should also add the Apple definition of DisplayP3 to the spec ref database and then add that reference to CSS Color 4.