Re: Agenda: Low Vision Task Force 23 Aug 2019

> On Aug 21, 2019, at 10:21 PM, Felix Miata <mrmazda@earthlink.net> wrote:
> Andrew Somers composed on 2019-08-21 21:26 (UTC-0700):
>> Of course 1u does not yet exist, nor the support — for a unit like 1u to be
>> really useful, browsers, phones, etc, would need a setting where the user could
>> enter their normal preferred viewing distance, which the user agent would then
>> use with the display PPI to determine the size to render 1u to make it fit to
>> 22 arc minutes.
> More units are not needed. All that's needed is to put a stop to abuse of existing
> units, and users.

Thanks for the reply, Felix,

To be clear, I'm not saying that a universal unit as in 1u is the answer, but the merit lies in that it is intended in a way similar to CIEXYZ - a “Standard Observer” point of view. 

> 1rem already exists, and could be a perfect unit for all purposes. The user picks
> an optimal size to equal 1rem.

I considered that while I was writing my earlier post. I dismissed it because the REM has other uses, and is not well suited as I will detail. But also, my original point is to have a unit, at the very least for research purposes, that is relative to a STANDARD OBSERVER, and not relative to a particular device or user agent, per se.

The concept I was bringing was not about UNITS so much as it was about defining a Standard Observer.

> That choice automatically accounts for acuity and
> viewing distance. That size as to anyone or anything but himself becomes
> immutable.

I don't think REM is the answer. One reason relates to the functionality of MEDIA QUERIES and RESPONSIVE DESIGN. The requirements of responsive design have brought us more, not less units. vw and vh in particular. 

The idea for 1u came from related research in ADAPTIVE TECHNOLOGY, and looking for a functional way to introduce Adaptive Tech. I discussed this at some length in a thread in the WAI list, though the archives lose all the formatting and illustrative attachments.

One of the point I made was… where here’s a snippet:

> …. the best fix is increasing the size of the text. But it is both unreasonable and impractical to set a minimum font size of 44px for all web pages! 
> 
> Among other things, while someone with severe low vision impairment may need 44px text, such a large size for body text will HURT the reading speed for those with lesser impairments or near normal vision. …..SNIP…..what IS needed, is the ability of a user with 20/200 to adjust the content. But just zooming it ALL up is ALSO not "most useful". Consider a page with 16px body text (which needs to increase 2.75x to get to at least 44px) the page has some subheads at 24px that need to get up to… …..Up to… 

> …..If a guess was "24 px text need to increased to 66 for 20/200", that's actually wrong. Just as that page’s normal 36px headline certainly doesn't need to leap up to 100px !!!
> 
> Just because someone’s minimum acuity may be at 44px (a 275% increase) does not mean that text larger than 16px must all increase that same amount. And increasing the large 36px headline to 100px could potentially HURT the 20/200 individual, making it too big to fit on screen but moreover:
> 
> Those with degraded acuity (and contrast sensitivity) don’t simply need “everything larger”. Think of the impairment more as a narrowing of the total range, and not a linear shift of {all values] SNIP….
> 
> ADAPTIVE TECHNOLOGY
> So in this case, the example of useful adaptive technology would allow the low vision individual to raise the size of the small body text, but make proportionally smaller increases of the larger subhead and headline text. Adaptive technology means the author’s original CSS stylings are not thrown away, but simply modified, and modified in a proportional way….


The REM is not at all suited to that. The rem, being root em, is typically relative to canvas px, but not so much to the non linearities of perception.

> The computer computes how many device pixels are required to produce
> 1rem or any fraction or multiple thereof. No logical px unit is needed. For
> bitmaps, the computer computes an appropriate way to convert from pixels to rem
> according to context.

I think that is misunderstanding the purpose of the CSS px unit, which has special properties useful to designers far beyond bitmaps. And it should not be confused with “old school" HTML PIXELS. 

The CSS px is relative to the canvas, an abstraction layer that separated CSS and CSSpx from display resolutions back when HTML pixels (not px) were still 1:1 with the display.

> There's no need for designers to depend on device px ratios
> or apply special handling for "high DPI" or any of the other kludges to pretend to
> accommodate varying physical densities or screen resolutions or visual acuity. In
> short, a web designer designs perspectives, but the user has automatic and
> complete control over how those perspectives translate into physical sizes.

A web designer designs content, and today is tasked with content designs that have a functional dynamic aspect for responsive design. And no, the user does not have "complete control" over the designer's perspectives as you call them, other than to OVER WRITE THEM AND REPLACE THEM. That’s not control over a design, that’s throwing it out wholesale, and losing all the benefit of the designer’s choices.

Which is a significant identified problem. 

What users NEED is the ability to proportionally adjust size, spacing, contrast. 

Interestingly this will HELP designers for the obvious reason that proportional adjustments stress responsive elements less.

> CSS should never have included the px unit. It's the reason why the web is so hard
> to use, and to design for. Deprecate the px unit ASAP, and soon after eliminate
> its support from web design elements other than bitmap images.

No, I really can not agree here at all, and I think you may misunderstand the the px unit. The px is relative to the Canvas, and the Canvas is defined by the px. The px is not some random abstract unit, it is relative to the Canvas, and the Canvas coordinates are measured in px, and it’s been this way since CSS was created in the 90s. The px's value to designers and developers has little to do with bitmapped images.


Regards

Andy




Andrew Somers
Senior Systems Engineer
Myndex Technologies  <http://www.myndex.com/>
Contact Redacted