W3C home > Mailing lists > Public > www-style@w3.org > December 2010

Re: Defining safe areas for media devices and set top boxes

From: James May <css@fowlsmurf.net>
Date: Sat, 4 Dec 2010 10:08:53 +1100
Message-ID: <AANLkTimR1kK3HLHPZnCOfcXOVTDHgg6k2ndPKeaEYu_Q@mail.gmail.com>
To: David Singer <singer@apple.com>
Cc: Chris Lilley <chris@w3.org>, "Robert O'Callahan" <robert@ocallahan.org>, João Eiras <joao-c-eiras@telecom.pt>, "www-style@w3.org" <www-style@w3.org>
Many lower-end flat screen (Plasma and LCD) screens have uncontrollable
overscan.

Well, that's been my experience anyway.

On 4 December 2010 09:12, David Singer <singer@apple.com> wrote:

> Chris has it.  The area outside the safe area is an area that the content
> author wants to paint, but he knows that the physical display edge will
> occur somewhere in it.
>
> I have to say, this was a problem with the gain tubes on CRT displays.  It
> used to be true that one would adjust the horizontal gain (using a rheostat)
> so the picture was safely away from the physical edges, but that leaves an
> ugly black border on the screen.  Then it became fashionable to raise the
> gain on the horizontal scan amplifier, so the picture extended to (and
> slightly past) the edge.  Temperature and other variations mean that the
> precise position at which horizontal flyback occurred was not stable.  There
> were also quality-of-focus issues towards display edges (as the tube rounded
> off).
>
> You might notice that the preceding was written describing analog tube
> amplifiers applied to scanning CRT displays.
>
> AFAIK, you can use all of a digital display.  Are we expecting web browsers
> to be written on devices that have this as an issue?  Are there digital
> displays which (deliberately, I guess) do not display all the margin outside
> the safe area (maybe on the grounds that it's boring)?
>
>
> On Dec 3, 2010, at 1:58 , Chris Lilley wrote:
>
> > On Friday, December 3, 2010, 9:55:43 AM, Robert wrote:
> >
> > ROC> Either I'm particularly slow tonight or your message is unclear.
> > ROC> Why can't you simply set the browser viewport to the "safe area" of
> the TV screen?
> >
> > The safe area on TV is not exactly like a browser viewport, and not
> exactly like page margins.
> >
> > In some ways its more like the bleed area on printed material. There can
> be stuff outside the safe area (solid colours, images, textures) and
> depending on how its cropped for final display some or all of that area may
> be visible.
> >
> > The 'action safe area' is outside the 'title safe area' and can have
> images and video, and will be visible, but must not contain text.
> >
> > See
> > http://en.wikipedia.org/wiki/Safe_area
> >
> > --
> > Chris Lilley   Technical Director, Interaction Domain
> > W3C Graphics Activity Lead, Fonts Activity Lead
> > Co-Chair, W3C Hypertext CG
> > Member, CSS, WebFonts, SVG Working Groups
> >
> >
>
> David Singer
> Multimedia and Software Standards, Apple Inc.
>
>
>


-- 
-- James May
Received on Friday, 3 December 2010 23:09:53 GMT

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