Never Use White Text on Black: Astygmatism and Conference Slides (2017)
jessicaotis.comI work in accessibility and see lots of posts like this one — cautioning the reader from every doing X because it creates accessibility problems for me.
It may be possible to follow most/all such advice when building an app or website, but surely it is not possible for presentations (which have to be consumed in the same format by everyone present). Some may hate dark text on a light background; others may find that the only suitable format.[1] So when I read posts like these, I don't view them as imperatives ("never do X") but rather as data points to be factored into decision-making processes.
This is easiest when the post explains the problem and gives various alternatives and explains why they provide a better experience. When they just leave it at "never do X", I'm left wondering whether Y is better than Z or vice-versa. I wish the author had given more context about why this is bad for astigmatism, or what sorts of things are better than others (in terms of ranking alternatives).
1: I hear from people who say that the only decent color scheme for BeeLine Reader (my text accessibility startup) is bright red and bright blue. But other people tell me that color scheme is terrible and shouldn't be the default on my website because it is so bad. You literally cannot please all of the people all of the time! [edited]
Like other commentors, I have astigmatism. Something not mentioned by other commentors; I have highly asymetrical astigmatism. Reading #FFF against #000 (dark on light or light on dark, either way) with both eyes open causes vividly strobing blue and red visual artifacts.
Stark black text on stark white background can do this, even though stark white background washes out the color artifacts to some extent. Fortunately, it's extremely unusual for anyone to lay out a page as #000 text on a #FFF background.
White text on a black background is a strobing hell. A dead black background is the perfect place to notice visual artifacts. Blazing white text sets visual artifacts effectively. Regardless, I use light-on-dark for much of my work. The problem I run into is that websites often end up being white-on-black, not light-on-dark. Light (not-white) text on a dark (not-black) background is pleasant, and my normal configuration for work.
Web design tutorials typically point out that #000 text on #FFF background is bad, and avoiding such extreme contrasts can be easier on the eyes. For whatever reason, that bit of know-how seems to vanish as soon as it's flipped to "dark mode".
Thanks for the detailed description! It's interesting to think about how one would meet these needs while simultaneously meeting the needs of people with scotopic sensitivity (prefer light text on dark background) and vision loss (require high contrast).
Honestly it seems like this three-way comparison is excellent evidence for the need for user-configurable reading options. It is unfortunate that on mobile, there are no browser plugins (except Firefox on Android, which is little-known, and action extensions on Safari, which is both little-known and does not support persistently-running plugins). As the world has gone mobile, we've ended up working/reading in app silos that cannot be made more accessible/configurable by plugins.
Speaking from my own disability I'd say I'd much prefer if people used white on dark text over any use of light background. But this is because my own issue is with photosensitivity which affects a large number of low vision users.
In fact I often create white on black content because it is easy for me to author and read. I also have significant color blindness and am totally unsure which color combinations are hard for others to read, may not show up on a projector, may be a faux pas or may be gaurish.
And this is the profound difficulty of creating accessible content. What is accessible for one is often not accessible for others with a different disability. Simply saying don't do this or don't do that has long ceased to be considered a good method of creating accessible content. This has been abandoned in favor of using a broad suite of tools to validate content meets a wide array of accessibility needs.
Edit: I have never looked into whether such a tool exists for common slide presentation apps.
Maybe you find this browser extension useful: https://darkreader.org/
Thanks. On desktop I use Windows High Contrast Black which is excellent. Firefox does a pretty good job of modifying web content to follow that theme. The main issue I haven't solved is mobile browsing. Most mobile browsers don't allow extensions and the OSes don't have anything like Windows High Contrast Mode except invent but that's never been a great solution for me.
This extension works on mobile firefox
Dark Reader in dark mode with the contrast turned down has saved me from soo many migraines <3
If both options cause problems, you should pick the one with the best workaround. Sunglasses can reduce brightness, but increasing brightness is much more difficult, so dark text on light background is correct.
No, sunglasses aren't going to fix contrast sensitivity due to photophobia. As a low vision person putting on sunglasses inside just means I can't see anything.
It’s possible to get polarised lenses that have about 50% transmission which is quite comfortable for computer work. At least for me they are anyway.
I really don't get it... I have severe astygmatism (which caused amblyopia in infancy) among other visual defects. My glasses do the best they can but my corrected vision still has a lot of visual defects. My poor vision causes me trouble with a lot of day-to-day things, but white text on black background is not one of them. I experimented without my glasses and I still don't have a preference for black-on-white over white-on-black - they are equal.
Not really a fan of the ranty style without a solution.
On top of that, like another commentor mentioned, people with astygmatism typically wear glasses or contacts?
I have irregular astigmatism. In my experience, glasses and normal soft contacts do very little to correct it. Scleral contacts do a decent job with the astigmatism, but they have a few other issues.
I didn't think this was a problem as I assumed most people with astigmatism (myself included) wear corrective lenses or glasses.
Cylindrical correction in contact lenses tends to be both more expensive and not as good as glasses, so contact lens wearers with astigmatism may have this issue.
From my own experience, unless you are really, REALLY into sports, glasses are infinitely much more better in almost every aspect. Sure, if you are young, you might be afraid you look like a nerd, but trust this old fart, after 25 or so it does not matter at all; if anything, you are perceived as smarter.
What’s the alternative? Hopefully not black text on white slides. That’s terrible for me and others.
For me, I find that a very dark gray background with a light gray text color is best. I like dark themes, but I get "ghosting" if the contrast is too great.
This is hard for virtually everyone to read. I don't think making the reading experience terrible for 99.999% to make it work for 0.001% makes much sense.
I think what I described is what a lot of dark themes use. For example the NY Times Android app. Their light text color is not pure white, and the background is not pure black.
Could you go into more detail as to why? It actually is my preferred style of presentation. Hopefully you do not prefer yellow on blue, as it often gives me migraines, especially if there's lots of text.
Perhaps building an app that synchronizes conference slides to a phone and allows users to customize the contrast/appearance of the slides would help in this case?
I love that idea. It would let people requiring different contrasts etc see the content too.
It won't help with pictures as easily, though a few apps these days do full PDF renders in different colours without much hassle.
I am definitely in the no black background white text camp and on the web I have a javascript bookmarklet to zap the colour CSS and make everything rather plain looking. It's not all text for me, but particularly dense text is unreadable, even with my glasses on.
Let me see if I can rally some folks on the Office team to build a PowerPoint companion app that does this. I think they have a hackathon coming up ...
I wanted to experiment with VLC broadcasting over wifi for my workshops. It could reduce dependance on projectors, I encounter 1024x768 ones, as an Indian.
Also as someone with myopia - so much better to read text from a smartphone than from the back of the auditorium!
I'm surprised the author didn't show examples of what would be preferred for comparison.
This describes my own personal experience with dark themes, difficult to read.
My experience is the opposite. Having switched entirely to light on dark (as well as adjusting the blue component of my screens to zero), switching the display of information back to dark on light feels like a nuclear blast of a million Suns into my eyes.
How can anyone stand staring directly into a bright lamp all day long? Well, having gotten used to it, you don't notice how unhealthy it truly is.
Working in a properly lit environment, with a blue filter enabled, it sometimes feels like the papers on my desk are about the same brightness as my monitor.
At home during the night I have to turn the blue filter up until the monitor is practically glowing orange-red.
I've seen the Apple stack render dark mode apps crisply but Linux+poorer screens making the same apps headache-inducing.
I have astigmatism. White on black or black on white both halo. I think both are equally clear.
It would be somewhat surprising otherwise-- the relevant part of vision for this is linear and should work the same in both directions. Though if the room is so dark that my puples will be dilated then that is obviously going to cause a loss of acuity ... but if that is what the author is going for then the advice should be to not present in a pitch black room.
In a dimmer room I have a small preference for white (or green/amber) on black so that the overall brightness isn't blowing out my vision.
Blue focuses noticeably worse, so I have serious trouble reading things like blue on black or black on blue... esp if the blue is some fancy LED sign or something that uses a shorter wavelength.
I think articles like this that don't support their advice with some kind of study of many people ... is pretty low value because it's too likely to just be repeating the author's own personal preferences and disguising them as research supported Truths.
Safer advice would be: Some people have poor vision, make your text extra big and clear even if you could read something less legible.
Maybe this is victim-blaming, but my suggestion to the post’s author is to update her prescription. I have astigmatism. This solution worked for me.
Not all astigmatism is easily corrected with glasses/contacts. I suggest reading up on irregular astigmatism: https://www.warreneyecarecenter.com/better-vision-correction...
That’s interesting. I had not heard of this condition.
I am sympathetic to those with disabilities different from my own. As a presenter, I would be happy to provide reasonable accommodations. Given the vast array of visual disabilities, I wonder if there is not some kind of common denominator solution, like providing a plain text, screen-reader-compatible version in advance.
I’m actually thinking, I wonder if I should build a service where one: 1. Uploads slides. 2. Gets a QR code. 3. Puts the QR code on the title slide. 4. Attendees point their smart phones at the presentation to get a: a. downloadable copy of the slides b. alternate versions c. other materials like the presenter’s LinkedIn d. a field for posting questions
If someone reads this and wants to build it, please go ahead.
White text on black is my second favorite. Only thing better is green text on black.
The reason is very simple: There's less light coming from the screen into my eye.
Every monitor I've ever owned I reduce the brightness to the lowest setting possible, and they are still too bright.
Green is best because the high resolution parts of your eye only see green. So the blue and red components of white are just unnecessary extra light.
Oh boy, are you going to love this state-of-the-art new display technology: https://c1.staticflickr.com/5/4142/4765726924_0c81d46a5b_b.j...
(Seriously, though, there may be an underlying physiological reason why the glow of a green phosphor CRT was so pleasing...)
I always set my IDE to emulate those green CRT's when I can.
But there is an underlying physiological reason, see: https://gamesx.com/misctech/visual.htm (the website is very old and has aged badly, but makes the point).
Your eye has no ability to see blue in high resolution.
For me it's Emacs in a terminal, set to a nice chunky bitmap (or bitmap-alike) font and #7fff7f foreground on black background. :) (For amber, try the X11 color "goldenrod", or #daa520!)
I'm aware of cool-retro-term. It is cool, but not useful for more than five minutes or so at a time.
I'm curious about your experience with HDR / other real-black displays. I have the same "problem", but find the new TVs with high contrast / darker blacks much nicer to look at. New MBP seems good too. I haven't tried a HDR monitor at home though - maybe you have some experience?
Being unable to stand both white text on black and black text on white, I have found setting the foreground to black and the background to gray60 (in emacs and the terminal) is what allows me to look at a screen for hours without pain.
(Interestingly enough, I too have an astigmatism in one eye, but I don't know if that's the sole cause of my discomfort.)
that's a bit disappointing, seeing as this format is by far my favourite because of it being very simple and aesthetically pleasing.
any suggestions? my intuitive response to this would be black on brightly hued navy blue, but i worry that is also low-contrast, which also causes issues.
can't please everyone!
This option sounds like it would be a poor reading for all. You can't please everyone but it seems like you can figure out how to displease most.
https://imgur.com/a/I1jFrG8 this doesn't seem that bad, but maybe my phrasing of the colors was inaccurate.
I pictured black text on darker blue background. That is readable enough.
Black on white. That is #000000 on #ffffff.
i think this is the 2nd best option, not the best: as someone who deals with artsy stuff more than pure information (or more accurately, i prefer to interpret the goal of transmitting information as an artistic task), i find that too much white tends to overpower any graphics you have on the screen.
the benefits of a physical white background is because your lighting will make background/subject evenly lit, but on a computer screen, the white just tends to overpower.
As a person with astigmatism and very familiar with halation, I always felt like white on black was almost equivalent to black on white. It seemed to just come down to personal preference or mood...
I see the white on black ok for a few moments, but soon my eyes can't see anything (or rather, can't discern shapes and text and such).
The worst are websites with white text on black backgrounds. Arstechnica used to do this, and I was unable to read more than a paragraph or two. Then when I would leave and go back to normal sites, I would have all kinds of weird ghost blocks in my vision (character sized).
Ouch. Don’t read the NZ Herald’s front page today then!
https://www.smh.com.au/sport/rugby-union/mourning-has-broken...
I have significant astigmatism and I prefer light text on a dark background. When I used a Mac, I found the best solution to get everything dark enough was to use a light theme and used Mac’s Accessibility Menu to invert the screen colors. I spend 7-8 hours a day on a dark terminal with light letters.
It's even worse for people with multifocal intraocular lenses implanted after cataract surgery: they see strong glares and halos around light objects on dark background (including text), and unlike astigmatism this cannot be corrected with glasses or contacts
With DLP projectors, white on black also causes way worse rainbow effect for people that are sensitive to that.
On mobile, this site has a “toggle high contrast” widget on the left side that seems to directly contravene the points made in the article.
Not just mobile — it's on desktop too. I also saw this toggle and thought it a little ironic. OTOH, this is an opt-in feature that a reader can activate, as opposed to a presentation that must be absorbed by everyone in the audience as-is.
Agreed, I just found the juxtaposition of the two confusing at first.
I have astigmatism and I have no idea what the author's talking about. I stare at white on black terminal text all day without issue (maybe it's different for presentations?). I've also made presentations with white on black text before and had no problem reading the slides.
If the overall environment is really dim, your pupils will dilate. Like opening the aperture of a camera this will make the area of correct focus smaller.
... but if the room is so dark that the presentation background alone is all that is keeping my eyes from dialating, then I'm going to find the presentation uncomfortably bright.