<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">I appear to have answered Matthew without cc'ing the mailing list!<br><br>Last year I installed several linux boxes in the local blind centre
with the large yellow on blue a11y theme. The overwhelming response
from all users was that the contrast was poor. When I asked them the
best colour combinations almost all preferred yellow on black to yellow
on blue. I switched the scheme to the large white on black theme which
was much more preferable. As I recall the favorite colour combinations
were yellow on black and green on black but I'd have to confirm that.
As an optometrist who runs a low vision clinic I cannot think of any
particular segment of the visually impaired who would benefit from
yellow on blue. If anybody is using this theme I would be interested to
know what their visual impairment is because I have still found nobody
who uses it.<br><br>I have been puzzling over who would use the yellow on blue scheme for some time. I genuinely think yellow on black would be a far better scheme for the visually impaired. I'll give the technical explanation as to why later today when I have time, I'm between clinics now!<br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">----- Original Message ----<br>From: Gunnar Schmi Dt <gunnar@schmi-dt.de><br>To: kde-accessibility@kde.org<br>Sent: Thursday, 24 January, 2008 2:07:16 PM<br>Subject: Re: [Kde-accessibility] how blue must blue be for blue-on-yellow color scheme?<br><br>Hello,<br><br>On Montag, 21. Januar 2008, Matthew Woehlke wrote:<br>> [...]<br>> Ok, so I keep hearing that blue-on-yellow colors are for a11y<br>> specifically... that being the case, I suppose I'm going to go ahead
and<br>> add that scheme to kdea11y.<br><br>I created all three high-contrast themes (black on white, white on
black, <br>and yellow on blue) for KDE 3.x after I read somewhere that they are <br>necessary. However, I did not really ask for specific reasons at that <br>time, and the only color scheme where I had input from people with low <br>vision is the white-on-black color scheme, so I do not know whether the
<br>yellow-on-blue color scheme really meets the needs of those persons
that <br>may need such a color scheme.<br><br>> What doesn't entirely make sense to me is what's wrong with<br>> white-on-black for most cases (rod deficiencies as opposed to cone<br>> deficiencies, where someone can tell about colors but not
lightnesses?).<br>> Anyway... how important is it that the blue be #0000ff as opposed to<br>> #0000c0 and there-abouts?<br><br>I would guess that people with rod deficiencies are unusual. From my
basic <br>knowlodge about how the eye works I would guess that even these people
can <br>tell the difference between white and black, but they might not be able
to <br>differentiate different shades of gray that easily.<br><br>I know, however, that there are people that need a high contrast,
mostly <br>dark color scheme, but for whom white text on a black background is a
too <br>large contrast (they are dazzled by the white and therefore cannot read
<br>what is written). I would expect that the yellow-on-blue color scheme
is <br>needed for these persons as yellow is darker than white (and brighter
than <br>blue) and blue is brighter than black (and darker than yellow).<br><br>> Put another way, would the scheme in [1] (that tries to balance being<br>> blue-on-yellow with "something that won't cause blindness in 'normal'<br>> people ;-)") be adequate, or do things really, really need to be<br>> #ffff00-on-#0000ff?<br>><br>> 1: <a href="http://img178.imageshack.us/img178/3632/olympusrh8.png" target="_blank">http://img178.imageshack.us/img178/3632/olympusrh8.png</a><br><br>As I have said above, I created the yellow-on-blue color scheme without
<br>feedback from users of it. In fact, it is a modification of an earlier <br>version of the white-on-black color scheme where white is replaced by <br>yellow and blue is replaced by black.<br><br>If my assumption about possible users of the color scheme is correct, I
<br>would argue that the scheme you suggest is problematic in the way that
it <br>increases the contrast of the yellow-on-blue color scheme by partly <br>lightening the yellow and partly darkening the blue.<br><br>That said, the theme looks much better than my attempt on a
yellow-on-blue <br>color scheme to my non-impairmed eyes (but as I said, it may not be
what <br>the users of a yellow-on-blue color scheme need).<br><br><br>> Matt Blissett [...] noted that the selection could use more contrast<br>> (actually, there is already more contrast than in the KDE3 version,<br>> but it's still not very good). What's the safest way to do that; make<br>> the selection lighter, or everything else darker? Or is it "good
enough"<br>> and changing it is likely to cause problems?<br><br>Please keep in mind that persons with low vision need a good contrast <br>between the text and the background color in order to be able to read. <br>Differentiating the brightness between two different shades of
background <br>colors can be done with a far smaller difference than reading text.<br><br>I hope that my comments are usefull for you,<br><br>Gunnar Schmi Dt<br>-- <br>Co-maintainer of the KDE Accessibility Project<br>Maintainer of the kdeaccessibility package<br><a href="http://accessibility.kde.org/" target="_blank">http://accessibility.kde.org/</a><br></div><br></div></div></body></html>