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Re: [WebVTT] It's not easy being green

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 18 Mar 2015 06:49:59 +1100
Message-ID: <CAHp8n2ndiVmcAKovQXK26drU2mXUJQES9q0DBXMkw8X8byNgiQ@mail.gmail.com>
To: Michael Dolan <mdolan@newtbt.com>
Cc: Public TTWG List <public-tt@w3.org>
WebVTT doesn't say anything about making color. There is a draft document
that has done suggestions as to what to map 608 and 708 colours to when
using css and WebVTT and it says lime (for quite some time now and as a
consequence of that presentation).

Best Regards,
Silvia.
On 17 Mar 2015 11:04, "Michael Dolan" <mdolan@newtbt.com> wrote:

> I received an email from someone studying SMPTE-TT and WebVTT who wrote
> and presented a paper about 18 months ago titled, “'It's not easy being
> green - a closed captioning for web case study'”.  Among other things, he
> observed that we map CEA 608 “green” to SVG/CSS3 “green”.
>
>
>
> FYI, the SVG/CSS3 RGB value of “green” is 008000, not 00FF00 you might
> expect (which is the color “lime”):
>
> http://www.w3.org/TR/css3-color/#html4
>
> Note in contrast that “red” and “blue” are both full brightness.
>
>
>
> Of the various 608 mapping documents….SDP-US uses only RGB values (no
> color names) and explicitly defines “green” to be 00FF00.  However both
> SMPTE-TT (RP2052-10) and WebVTT say to map 608 “green” to TTML “green”
> which is minimally inconsistent with SDP-US. The same would be true for 708
> mappings, of course.
>
>
>
> Of historical note, CSS1 says the color palette came from the “Windows VGA
> palette”, which seems to have come from the CGA text color palette:
>
> http://en.wikipedia.org/wiki/Color_Graphics_Adapter
>
> (although the above  defines the brighter green as “light green”).
>
>
>
> We could assume it is supposed to be maximum brightness like “red” and
> “blue” (i.e. 00FF00), but on the off chance that “green” text overlay is
> actually handled differently in the billion TV’s out there I’ll ask a
> couple of set manufacturers….
>
>
>
> Regards,
>
>
>
>                 Mike
>
>
>
> -------------------------
>
> Michael A DOLAN
>
> TBT, Inc. PO Box 190
>
> Del Mar, CA 92014
>
> (m) +1-858-882-7497
>
>
>
Received on Tuesday, 17 March 2015 19:50:28 UTC

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