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RE: Color Management in HTML5?

From: Leonard Rosenthol <lrosenth@adobe.com>
Date: Sat, 6 Mar 2010 05:29:56 -0800
To: Maciej Stachowiak <mjs@apple.com>, "L. David Baron" <dbaron@dbaron.org>
CC: "public-html@w3.org" <public-html@w3.org>
Message-ID: <D23D6B9E57D654429A9AB6918CACEAA97CA6084E51@NAMBX02.corp.adobe.com>
And this discussion is EXACTLY why the ICC wants to get involved.

As has been stated many times, the HTML5 spec is not only about the language & grammar BUT is also a set of requirements for UAs to ensure that all browsers render the same page in the same way.  As such, that includes not only that the right image goes in the right place on the page BUT that its colors are correct and match the colors shown in other browsers.

To accomplish this will mean that rules for color management within a browser need to be stipulated in the standard itself.   For example, the following (non-complete) list of questions need to answered...

*         What is the "default colorspace"?

*         How to handle embedded profiles in images (and possibly even how to look for them)

*         How to handle CSS colors

*         How to handle SVG colors (which extend CSS a bit)

*         Does Canvas need to be extended to deal with richer color (ala SVG)?

*         Does video need to be extended?

Would the correct process forward then be for the ICC to draft one or more formal & comprehensive Change Proposals (which will most likely be fairly widespread throughout one or more of the documents currently being authored)?

Is it possible that some form of decision could be made to determine the "feelings" of the committee ahead of time?  I would hate to recommend to someone at the ICC that they invest the (huge) time necessary to draft such a document , only then to have it not approved.  Is there some sort of "pre-vote" or something that could be used in this case?

Leonard

From: Maciej Stachowiak [mailto:mjs@apple.com]
Sent: Saturday, March 06, 2010 7:15 AM
To: L. David Baron
Cc: Leonard Rosenthol; public-html@w3.org
Subject: Re: Color Management in HTML5?


On Mar 5, 2010, at 2:04 PM, L. David Baron wrote:


On Friday 2010-03-05 00:08 -0800, Maciej Stachowiak wrote:

Just to report on what Safari does: we colormatch images that are
tagged with an explicit colorspace, but we treat CSS colors and
colors in untagged images as being in the device color space
(instead of treating as sRGB). This seems to give a good balance
between performance for the common case and color-correctness for
cases where precise color is desired.

Gecko does this too (I think starting in Firefox 3.5?), but we got
quite a few complaints about it, and I'd like to change it.

It has the significant disadvantage that the relationships between
colors in different parts of the same page can be different
depending on the device (when a page has both tagged images and
other colors).

I think we should move towards treating CSS colors (and untagged
images) as sRGB, as CSS1, CSS2.1, and css3-color require.

Long-term, we would like to do this in Safari (treat CSS colors and untagged images as sRGB). In our attempts so far, there have been two blockers:

1) Our attempts to do this so far have resulted in significant performance regressions. We're still working on a way to do this with good enough performance.

2) We have no way to get plugins to participate in colormatching. We need additions to NPAPI to tell plugins whether to use device color or sRGB, and we need plugins to adopt them. This is especially critical for Adobe Flash, since there are pages that try to match static background colors or background images to Flash. We've had some discussions on this.

Regards,
Maciej
Received on Saturday, 6 March 2010 13:30:51 UTC

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