Re: Pixel, Points and Spatial Measures

On 13/01/2017 08:03, Wayne Dick wrote:
> In web jargon 12pt = 16px, a flexible measure. To the rest of the
> publishing world, 12pt = 1/6 inch= 5/24 cm, a spatial measure. We will
> ultimately talk to web developers in pixel because pixel is the unit
> of web measurement. I propose omitting the use of point size as a
> measure in our discussions and speak only in pixels for screens size
> and centimeters and inches for spatial size. It is sad, but point has
> become ambiguous.
> There is a serious but solvable problem when we apply pixel measures
> to low vision accessibility. People with low vision need real spatial
> measures for their font sizes. A person with low vision cannot read
> print with 0.139in= 0.347cm font size (newspaper font) from 16in=
> 40-cm (comfortable distance). I cannot give a pixel statement like
> that, because what a person can see is determined by the angle it
> subtends on the retina. The same pixel count will have different
> spatial sizes and subtend different angles on the retina for different
> screen sizes and resolutions.
> I propose that in font size issues for low vision we use spatial
> measures, and give conversion tables for developers. We can give our
> developers conversion tables in the techniques.  I can do it with
> centimeters and inches. The problem isn't that difficult, at least for
> me, a resident mathematician.

Don't want to start yet another epic thread, but once more: there is no 
way to require a particular spatial measure from developers, since they 
have no way of controlling how their content is actually rendered, at 
what size. That depends on the physical size of their screen and the 
resolution it's running at, and the actual physical size is something 
that authors have no way of knowing nor detecting.

Once more: as an author I have absolutely no control over the actual 
spatial size, in real-world physical units, of my content.

It's not possible to provide a conversion table, as there are variables 
(the physical size of the screen, the resolution that screen is running) 
- there's no simple "X pixels equals Y centimeters/inches".

> if we do not state our SCs in spacial measurements we will have not
> way of knowing if they work.

Patrick H. Lauke | |
twitter: @patrick_h_lauke | skype: patrick_h_lauke

Received on Friday, 13 January 2017 09:21:08 UTC