Most studies have shown that reading digital books written with black characters on white (light) background is better for the eyes than reading the same in white text with black (dark) background. In the experiments, the subjects read with 26% greater accuracy when they read with dark characters on a light/white background. The science (physics) behind this phenomenon is the following:

1) When the background is white, display is bright and the iris closes a bit more than normal and this decreases the effect of the "deformed" lens. With a black background the iris opens a bit more to receive more light and the deformation of the lens creates a much fuzzier focus at the eye. This is known as "fuzzing effect" or "Halation".

2) While reading an e-book, white stimulates, in nearly equal amount, all the 3 colour receptors in our eyes . This makes reading white text on dark background stressful on the eyes.

3)It is easy to read a digital book written in black text on white background because the light that makes us read each word and letter is not reflected but absorbed. This causes much less strain on our eyes. In the case of black background with white text, the effect is opposite because the reflected light from text scatter into each other. Addition of grey tint to the background improves the situation because it means less light reflects behind the words, making it easier on the eyes.

4) Black text works better because black is a colour that does not reflect light in any part of the visible spectrum.

5) White reflects all wavelengths of light. The characters in the book being compact and close, when white reading material reflects light, the reflected light scatters and runs into neighbouring words and letters. This makes the shape of the text material harder to perceive and this strains the eyes. In comparison, when the text is black, the black colour absorbs the light around each word and letter making them easy to distinguish from one another. This causes less strains on the eyes.

6)With a tint of grey in the background, less light reflects behind the words, making it easier on the eyes. Since black colour does not reflect light in any part of the visible spectrum, the black text works better. Therefore, fixating on black text while reading will not put as much stress on the readers' eyes because it absorbs the light that strikes each word.

7)If you use a dark background, the text should be displayed in grey tint. This will not put as much stress on our eyes because grey text is not as bright as white text. It reflects less light making it easier to read. In a dark room, white text on a black ground is not much stressful on the eyes. This is because no light is reflecting off it in a dark room.

8) Black text on a light-grey background is easier to read than in a white background because less light is reflected behind the text. Grey text on dark background is easier to read than white text on dark background because less light is reflected on words.

9) While scanning text, white text on dark background is fine. White reflects all the colours of the visible light spectrum into the eyes. This makes the text look bright and distinct. Since scanning of a heading, a title or a label takes a quick sweep of the eyes, there is no worry as far as putting stress on the readers' eyes is concerned.

10)Black letters on white background can be bad for people with dyslexia.

11)Most readable colour combination is black text on white background.

12)Computer screens being projections, the black-white contrast is more pronounced than it is on a printed book. This increased contrast causes eye-strain quickly.

13)How the text material is placed on the page of a book is also important. If the reading material is embedded and/or part of graphic, size of pixel matters.

14)Nearly 50% of population have astigmatism and these people find it harder to read white alpha-numeric characters on black than black on white.

SEPIA MODE OF READING DIGITAL BOOKS: Research shows that switching from white to sepia background, the strain on the eye reduces since sepia spectrum is softer than the white spectrum. The effective radiance in sepia background is nearly 25% lower than in white background. This means lower screen luminescence and hence lesser visual fatigue, lesser strain on the eyes. Visual eye fatigue is lesser while reading in sepia background as compared to white background. There is more eye strain, blurry vision and tiredness in white background in comparison with sepia background.

It is the way that the light waves bounce and reflect off white and yellow. White objects reflect every colour wave to our retina, and we perceive this as white. To perceive yellow our eyes are receiving green, and red wavelengths in equal measure. That is only one wavelength short of white, and blue wavelengths are the shortest in the spectrum, so probably create greater definition.

The difference in the wavelengths we are receiving from yellow on a white background is not strong enough to create enough definition for our eyes to pick up.

A similar effect occurs when you use bright red, on an azure blue background. The wavelengths are so similar in strength they cancel each other out, and from a distance you get a flashing effect. All good sign writers are aware of this, these colours, and yellow on a white background is a no, no for legibility in signage.

I don’t think your question’s basic premise is correct. The opposite (black on white) is preferred by more people than white on black. Some people have no preference.

There may be several factors in play. But consider this possibility - when viewing white print on a dark background, the pupils open wider to allow more light. A wider pupil has the opposite effect of the pinhole and members of the audience who have astigmatism, uncorrected refractive errors, and/or cataracts have poorer vision when the pupils are wider. On the other hand, the pupils will be smaller when viewing dark letters on a white background, negating some of the refractive problems of the audience by mimicking the pinhole effect.

Now, if a person is slightly far-sighted and not wearing correction, it is possible that the mild myopic shift associated with a wider pupil may actually help that person see white on black better. This is a speculation on my part but it is something that could be tested, just don’t know if anyone has the motivation to carry out this particular test. Seems Powerpoint engineers could provide an answer or do the research (if they have any spare time).

Why?

Gross ignorance!

Usually websites without the expertise of a trained and experienced graphic designer. Probably done by a wannabe who thinks it is cool.

They do it because designers like it , not because it is effective at getting people to read the text.

And it drives away anyone reading the text.

Studies based on how the eye works shows light on white is only outdone in un-readability by black background with white letter.

Both violate the concept that nothing should reduce the probability that a visitor will read the text.

And that’s why so many websites never earn back the investment in sales from the site.

It's the result of eye's attempt to compensate for the overall scene illumination. The brain adjusts the size of the iris to provide a normalized light input from the eye; you squint in bright sunlight and open wide in darkness. When you squint, your visual acuity drops and you're not able to discern small details. For example, when you are on the road at night and facing an oncoming car with high beams on, you can't “see” anything except the bright lights.

Your question of black text on white background replicates this situation. The white background causes the iris to close down, obliterating the black text.

The white text on a black background reverses the situation: your iris opens wide effectively increasing your eye's resolution.

This is why I hate Android, apart from the fact that it is a stupid system using Java, requiring fast processors and heavy amounts of memory to operate.

In Windows, I can easily, and always change the colour of the window background to a light greyish-blue.

You will find that it is far easier on your eyes, and your black text will stand out even better.

I have been doing that since the days of Windows 95.

You have two other options in Android.

Use an eye filter. I use this. Get it on Playstore.

Use UC browser. You can change the theme to this, with a translucent background.

Notice that my background is actually “Bliss”, the default pleasant grassy landscape in Windows XP, which I downloaded from the net.

Notice too that my fonts are bold. I use Poppins Semibold.

UC however, has trouble with Quora’s and some sites, due to the heavy Java programming they have used in this recent version. It somtimes is able to display only the first two answers, unable to scroll down further.

Writing an answer is also slow and difficult, locking up the browser.

Colored pixels are usually part of a technique called “anti aliasing,” which attempts to smooth out jagged edges in digital text and images:

Et voila!

For some reason, various shades of gray are the default.

You can easily customize the text color and use a dark color for the text over a light background and vise versa.

It is really difficult to read faint type text on a white background, much easier to use black or dark blue/black color.

Note: re an earlier reply, black ink was the norm for most documents.

However, copiers, unless the color feature is used, all copied documents are black.

By using blue ink, you can quickly see tell which documents are the original from the copy.

Tip: when writing, signing, etc, on a document, turn the paper over and run your finger over the written area. You will feel the raised lettering due to the pressure caused by putting pen to paper.

Rudy

The effectiveness of white text on a dark blue background versus black text on a white background for reading longer articles depends on factors like eye strain, lighting conditions, and personal preference. Here’s a comparison:

Advantages of White Text on Dark Blue Background:

1. Reduced Eye Strain in Low-Light Environments:

Dark modes are often easier on the eyes in dimly lit spaces because they emit less light.

2. Energy Efficiency:

On OLED screens, darker backgrounds consume less power.

3. Less Glare:

White backgrounds can create glare, which some users find uncomfortable during extended reading.

Disadvantages of White Text on Dark Blue Background:

1. Reduced Readability for Long Texts:

Studies suggest that light text on a dark background can lead to halation (a glow effect around letters), making long reading sessions more tiring.

2. Eye Fatigue in Bright Environments:

In bright surroundings, dark mode can make text harder to read due to low contrast.

3. Lower Retention:

Some research indicates that people may have better reading comprehension and retention with black text on a white background.

Advantages of Black Text on White Background:

1. Better Readability:

High contrast and clarity make it easier to read small or dense text.

2. Widespread Standard:

Most people are accustomed to reading black text on white pages (e.g., books, documents).

3. Sharper Text Rendering:

Fonts generally appear crisper on light backgrounds.

Best Practice:

For long reading sessions in a well-lit environment, black text on a white background remains the better choice.

For shorter reads or low-light settings, white text on dark blue (or dark mode) can be more comfortable.

Many modern interfaces allow users to switch between modes depending on the time of day or environment.

In the end, personal preference and adaptive screen settings (e.g., dark mode at night, light mode during the day) are often the best approach.

Abi Buckholz requested your answer

Why is text blurrier when I read white on a black background than when I read black on a white background?

The way a graphic designer sees color is different compared to how physicists see color.

For the graphic designer mixing color, whiteness becomes the lack of color, black becomes the sum of all colors.

The physicists consider black as the absence of colors and white as the presence of all color.

There is much more about color, but to get the answer to your question;

Look up the halation effect.

Next look up astigmatism.

The graphic designer uses color to get a reaction from a target audience. Someone made that decision to use white text on a black background. This is the psychology of color sensation and involves making a color choice to stimulate an audience.

It stimulated you possibly in an upsetting way. Maybe you are not the primary target audience for what ever you saw in print or on the web. Anyway the perception you had is common. It is also sometimes an indication of a problem.

I hope you have access to healthcare. Abi, consider making an appointment with your ophthalmologist if it has been more than two years since your last visit.

Best success!

I don’t think its a matter of color (hue); but of value (light vs dark). White is the most extreme light value; black is the most extreme dark value. Both ‘contain’ all colors. So you need a mid-value color; any color (red, orange, green …etc). Your typical color names usually describe a mid-ish value, and the light or darker values are given distinct names.

For instance: pink = light value red; maroon = dark value red; red= mid value red. But the trick is … there are tones of shades between pink and maroon. And similarly with other colors. There is very light yellow; ‘yellow’, which is kinda light in and of itself - so white won’t show up on it so well, but a mid-value yellow is some kinds of tans.

To be safe: mid-value gray.

The whole purpose of paragraphing is to break up a narrative into chunks that are easily digestible. A well-structured paragraph helps the reader understand the writer’s reasoning and absorb each point they are trying to make. Much ink has been spilled on that subject, but let’s just say that in general a good paragraph should start with a proposition, take the reader through a series of arguments, and finish with a conclusion (or punch-line).

When paragraphs are clearly marked, either by an indented first line, extra line spacing, or both, it guides the readers eye to the starting and ending sentences and lets them focus their own train of thought on them. Everyone will have their own way of reading, but I find I usually read each paragraph without a break and pause briefly “for breath” between them. That is much harder to do if they are not clearly differentiated.

I am a great believer in the ergonomic benefits of careful attention to typography and layout. This is a largely unnoticed aspect of writing - and so it should be, being unobtrusive is a key feature of good typography - but if you want the reader to connect to your words, and not be distracted by fancy fonts or artistic page spreads, then it pays to devote some time and effort to it.

When computers were new, video cards and monitors were low bandwidth and poorly focused, characters were often white on a black background. People often complained that going from reading text on paper to text on the screen was hard on the eyes.

As soon as computer technology allowed, we switched to black on white text. It seems to work best.

Some studies were done that showed that red/blue, white/yellow, blue/black were terrible combinations. We don't distinguish blue with the same spatial resolution as green or red.

Black on white seems to work pretty well.

Now, will looking at white on black cause your eyes to go bad? There is no evidence that it does.

You remind me of a young Italian guy whose parents were well-heeled. He insisted to me he had to get a new high resolution high refresh rate monitor (with dad's money) “for his eyes”.

Found something useful:

Nothing about research. But…it’s something.