Practicality of Very Large Print and a Responsive User Interface for People with Low Vision
A lot of literature places a cap of approximately 200% on the
practical magnification size for large print. Larger than
that and many contend that extreme methods like changing to
Braille or use of screen magnification are the only possible
solutions. For example, "Students who need print 28 points or
larger should probably be considered as candidates for Braille
Printing House for the Blind). This set of
calculations shows that a very satisfying reading experience can
be obtained with up to 900% enlargement of 12 point font when
normal word wrapping is employed. Since word wrapping is one
of the oldest technologies of the personal computing and web era,
the technology to obtain this user interface is well known and
well within the means of any web author, media producer or browser
For many people with low vision it is very possible to read on a
laptop with a standard screen of 13.3 inches. Now a good print
size for normal readers is 12 point, where we use the Adobe
standard point size of 1/72 inch. Thus 24 point is 200%
normal, 36 point is 300% normal, 48 is 400% normal, 72 point is
600% normal and 108 point is 900% times normal. This range
should be sufficient to address the needs of people with mild low
vision (20/40-20/60) and moderate low vision (worse than 20/60 and
better than 20/200).
For less visual acuity, a non-portable solution using 20-36 inch
monitors would include approximately the same screen capacities
with nearly double the magnification. Note that 16
characters per line would involve some horizontal scrolling for
words larger than 16 characters. That would be very
infrequent in most languages.
If people with low vision were given a responsive interface,
whether it is obtained by a popular authoring technique like
responsive web design
(RWD) or by some other means, they can benefit. The only real
responsiveness required is reversion to one column format with
appropriate print size. In the intermediate ranges 36 point to 72
point, use of a portable device like a 13.3 inch laptop as a
reading device is extremely practical.
The main point is this. Responsive user interfaces are old in the
world of personal computing and the technology is well know. The
first was automatic word wrapping and WYSIWYG. That sold personal
computing to the general public. It was followed by early
Microsoft Windows systems that enabled the user's choice of icon
and font size, color and font face that propagated through all
Windows applications. This was lost with Windows 7 and
later, but the capability was established. Any entity who
cared to put in a little effort could establish responsive user
interfaces that would work for people with low vision. This
article demonstrates that for most people with low vision, there
is even a portable solution. No new technology needs to be
invented. All that is needed is a user interface that is built
with responsiveness in mind.
Wayne Dick composed on 2015-09-07 11:49 (UTC-0700):
> All that is needed is a user interface
> that is built with responsiveness in mind.
When it comes right down to it, all that's really required is to embrace the
user's choice of text size, whatever sizes those may be. That means not using
px units for sizing anything remotely related to text; to make the user's em
unit the unequivocal and immutable baseline for text and text container sizing.
The proof is in the result from user disabling author styles, such as
Firefox's View -> Page Style -> No Style. Dominant text size then becomes the
user's optimal, with other sizes determined by semantics and the user agent's
style sheet. IOW, responsiveness is restored to automatic with styles disabled.
The resulting problems follow from disabled author styles related to colors,
and positioning that's inconsistent with logical semantic structure. But
these pale in comparison to the fundamental need to be able to read text. Few
pages can serve any purpose if their text content isn't sufficiently legible.
Pages styling text using px units aren't designed for users, they're designed
for designers, to be looked at as if graphical images, not utilized for
whatever text content they provide.
The px unit needs to be stripped from all CSS contexts except those
exclusively related to bitmap images. It was wrong to ever have included px
unit applicability to sizing web text with CSS.
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)
Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!
Felix Miata *** http://fm.no-ip.com/
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