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Re: Color fidelity during transcoding

From: Chris Lilley <chris@w3.org>
Date: Tue, 29 Aug 2006 23:05:22 +0200
Message-ID: <6910289399.20060829230522@w3.org>
To: "Glenn A. Adams" <gadams@xfsi.com>
Cc: public-tt@w3.org

On Friday, August 25, 2006, 3:45:08 PM, Glenn wrote:

GAA> Your comment appears to make the assumption that the existing
GAA> legacy caption and subtitle formats for which DFXP is designed to
GAA> effect interchange have a defined model of color interoperability
GAA> that correlates with color interoperability in the underlying
GAA> presente video material.

You are correct that I made such an assumption.

GAA> However, our investigation of this matter does not indicate there
GAA> exists correlation or definition of interoperability regarding
GAA> caption subtitle coloring. In other words, the designers of these
GAA> legacy formats have similarly not defined color interoperability or
GAA> compatibility with the level of precision you are asking for.

Many thanks (really, and not rhetorically) for the useful documentation
in your reply regarding color fidelity for captioning in existing
systems.

GAA> On might then reasonable conclude that introducing a concrete
GAA> color transfer function that ensures optical interoperability of
GAA> caption and subtitle coloration appears to go significantly beyond
GAA> the state of the art with respect to the intended interchange of
GAA> DFXP with legacy caption and subtitle content.

You have convinced me that this is so. Thus, conversion to DFXP does not
introduce quality loss compared to the original in terms of color
fidelity.

GAA>  While this may
GAA> perhaps be an appropriate requirement for a more advanced, full
GAA> featured timed text authoring format exchange profile, such as the
GAA> AFXP profile that has been discussed in the past by the TTWG, there
GAA> appears to be no legitimate rationale for such a requirement in DFXP.

GAA> The TTWG respectfully requests that you accept the unanimous
GAA> consensus of the group on this matter.

I am happy to do so and withdraw my objection.


-- 
 Chris Lilley                    mailto:chris@w3.org
 Interaction Domain Leader
 Co-Chair, W3C SVG Working Group
 W3C Graphics Activity Lead
 Co-Chair, W3C Hypertext CG
Received on Tuesday, 29 August 2006 21:05:43 GMT

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