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

Re: Making pt a non-physical unit

From: David Singer <singer@apple.com>
Date: Sat, 16 Jan 2010 10:42:19 -0800
Cc: www-style Group <www-style@w3.org>
Message-Id: <7510EA4B-492C-4C54-8369-BBFE0F904731@apple.com>
To: Brad Kemper <brad.kemper@gmail.com>
Yes, maybe the 'subtends the expected angle' should all be subsumed into 'the sensible thing happens', and given as guidance of one way to decide what the sensible thing might be.

We do need some sort of convergence guidance, I think.

On Jan 16, 2010, at 10:37 , Brad Kemper wrote:

> On Jan 15, 2010, at 6:01 PM, David Singer <singer@apple.com> wrote:
>> In both printed and electronic 'billboard' displays, a CSS inch may be much larger, therefore, than a physical inch, so that a CSS pixel subtends the expected angle at the eye for the typical viewer.
> For electronic displays, this may happen to work out to the right angle through happy chance, or by the billboard manufactures making pixels that do not appear too large and blocky when you are some minimum distance away (and 'too blocky' might be based on expectations set by looking at desktop monitors at arms length). But I don't think you can say what a typical view is, because there is a great variety of viewing distances that are in good viewing range, and the pixel size will be based on some target minimum distance combined with cost and technology considerations. I don't think we should mention "subtends the expected angle", because it seems like an impossible fantasy to pick a typical distance, and unlikely to be considered by billboard makers. They probably develop their own guidelines for how far away their billboards need to be in order to be readable for a given pixel size. Anyway, I'm just critisizing rhe wording a bit (to avoid false expectations, especially as billboards also move to higher resolutions in the future), but I like what came before that sentence.

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Saturday, 16 January 2010 18:42:53 UTC

This archive was generated by hypermail 2.4.0 : Friday, 25 March 2022 10:07:42 UTC