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Comment by coder543 | Hacker News Reader

> It turns out that staring at back-lit computer monitors for 40+ hours a week might not be the best thing for you.

Source? Light is still hitting your retinas, whether it comes from reflection or from a backlight.

I really enjoy E-Ink displays, but not because of perceived health benefits from reflected light. I enjoy how readable they are under sunlight, how they consume zero energy to show a static image, and how this enables them to always show content even if the device has no power.

It's simply not necessary to use unsourced health claims to justify a great technology like E-Ink.

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https://news.ycombinator.com/item?id=17724995 Was a good thread

I don't see anything related to reflectivity vs. backlight illumination. Most of the discussion is around the wavelength of light (blue) and its effects.

does light have any other intrinsic properties besides spectrum/wavelengths and intensity (EDIT: properties that vary based on the light source alone)? It doesn't matter if it came from a backlight or reflection, the electromagnetic waves are still electromagnetic waves. If the color spectrum is unpleasant, it's possible to use Night Shift or other features to shift the spectrum. If the intensity is unpleasant, just turn down the brightness.

The problem is LCDs have much worse objective performance as the backlight diminishes. E-Ink has tragically bad contrast of 15:1, but it maintains that contrast ratio in low lighting conditions. LCD panels rely on high brightness for their contrast. At very low brightness, even the best LCD display has poor contrast.

OLED displays have a different problem; they have so much noise at low brightness that the image falls apart. Still, I think a monochrome OLED display is what the person who wrote this article actually wants. It would have better performance in every respect to E-Ink, and it doesn't sound like their application requires E-Ink's low power.

I have used both LCD and OLED smartphone displays at incredibly low brightness in pitch black rooms for a long time, and I have to completely disagree.

On the other hand, E-Ink is amazing in sunlight, where smartphone displays can't get sufficiently bright.

Which smartphone displays can you set to 'incredibly low brightness'? all iPhones and Androids I've used are like bright flashlights when the lights are switched off.

It's all relative. I don't own a single flashlight that can be set dimmer (or anywhere close to as dim) as my iPhone XS Max is at minimum brightness on a white page. If the XS Max is showing mostly-dark content, the amount of light emitted is really tiny at minimum brightness because of that OLED display.

On the various Android devices I've owned, I've used a useful app called Screen Filter that adds a translucent layer on top of all apps to dim the screen beyond the artificial manufacturer-imposed minimum brightness, which worked especially well on OLED Android phones, but also LCDs worked fine too.

Presumably, all or most Xiaomi phones. I've never used one for long, but the lowest backlight level in those I tested (Redmi Note 2, Mi A1, RN5) was comparable to the level 2 or 3 of the Kindle Paperwhite frontlight. (level 1 is a failsafe option since the Paperwhite has no physical buttons, it's not meant for reading, being too dark even for a pitch black room)

That said, I don't think reading in poor lighting conditions is a good idea for your eyes, no matter the technology.

You can use an app to reduce the brightness further. I've been using Twilight on Android, and it does indeed get much dimmer. You will certainly lose some image quality/performance, but it's very nice for viewing in a dark room.

This is actually a reply to @Romed:

My understanding too is that OLEDs can have "true black" pixels that emit no light at all. For "dark mode" style screens, this is a huge benefit, because the majority of the screen may simply be turned off. Conventional LCD screens still send current to each pixel, but the "black" is simply tuned to a dark frequency, rather than being altogether off.

Yes, an unpowered LED emits no light. But an OLED that's barely on, for example at uniform 1% grey looks like crap because of the noise. People describe this as a "texture" or "banding". It's the consequence of trying to drive millions of individual semiconductor devices to the same emissive power. At higher brightness you can't notice the noise.

Lcd screens are transparent and selectively block the light from a backlight. They can’t show full black because they can’t completely block the backlight.

does light have any other intrinsic properties besides spectrum/wavelengths and intensity?

Sure, think of things like polarizing filters, lasers, etc.

Lasers are just a method of creating light of a single wavelength. The light itself from the laser is still defined by its wavelength and intensity.

Polarization is just related to the orientation of the electromagnetic waves, and it is a property I didn't mention, you're correct. I don't think it really matters here, though. It's kind of like which direction you shine a light, except whether the waves are all oriented the same way or not. I would almost argue that it's an extrinsic property since uniform polarization is almost exclusively the realm of external things like filters, not the light source itself.

Your "etc." is a little vague.

You were suggesting light doesn't have any other 'intrinsic properties' and that's not the case - phase (a laser is not just a monochromatic light source) and polarization come to mind. Whatever it is you're trying to argue, 'light is just wavelength and intensity' is not a sensible starting point.

Is it not sensible, though? People are trying to argue that light from a backlight is inherently more dangerous than reflected light. The easiest way to dispel this notion is to establish that the light from a backlight is just light like any other, which it is. At most, it varies in spectrum and intensity. Polarization is affected by filters outside of the light source. The phase that's hitting your retina varies entirely based on irrelevant things like when the light source was turned on and how far away it is.

Starting by pointing out that intensity and wavelength are the only intrinsic properties is a great starting place.

You still haven't pointed out any additional properties that have any bearing on how your retina is affected. I was wrong the say that there were no other properties, since we can endlessly discuss the quantum nature of light or how it experiences no flow of time since it travels at the speed of light or all sorts of other properties...

but none of these things change based on the light source. Light is light, except for the intensity and wavelength. Unless we're willing to consider things which could affect reflected light just as much as they could affect emitted light, since they're the same thing. Light.

Light is light, except for the intensity and wavelength.

I'm not sure why you're so set on this obviously inaccurate thing and are now moving the goalposts to stuff about retinas and what the meaning of 'intrinsic' is. All I'm saying is both light and especially the perception of it are fairly complicated. You can just read up on it like everyone else instead of building a weird messageboard logic hill fort.

Yet you fail to point out the inaccuracies... I'm not moving the goal posts, I'm just clarifying where they were to begin with. You pushed them as far as you could within the wording of my original message, instead of taking the "strongest plausible interpretation" of my original message.

Also, if we go a little deeper, then intensity is really not intrinsic property of photons themselves. Photons radiate through space and are carriers of electromagnetic force. They have momentum but no mass. Its energy and momentum is a function of frequency (or wavelength). Furthermore, they also have spin angular momentum which is truly intrinsic as it does not depend on frequency.

So, the saying that light is just "intensity and frequency" is naive and flat-out incorrect.

It isn't possible to make light that is faster or slower than other light, so does it matter that some other property is derived from this constant* ? A property derived from one variable and a constant property is perfectly logical to refer to as intrinsic, since it's always exactly linked to one intrinsic property. Splitting hairs there doesn't make sense.

Which things can a light source vary, besides wavelength and intensity? It's easy to define intensity in this context as the photons being emitted per period of time. This isn't like trying to define the intensity of sound as an intrinsic property, when it really depends on a number of actually intrinsic variables.

*within a given medium, which is external to the light... which means it won't change based on reflected vs LCD.

I really don't understand what your point really has to do with the original discussion.

Ok, light can be described by its intensity and wavelength. So what? Can you tie this to the original parent post?

You can break it down further - intensity is just the "number" of packets (photons). So, really, light is just frequency and travels at max speed (C) because photons are massless.

Where are we going with this discussion?

Edit: I am not able to respond to you below so I am responding here. You're right on this one - it doesn't matter what the originating source is, light is light whether it is reflected or emitted.

The argument is that since the light is the same, it can't have different effects. Reflected light cannot be inherently healthier than light from an LCD.

Light from lasers is also phase coherent. This is in sharp contrast to LED, incandescent etc.

Yes, I know what electromagnetic waves are. I found your response very off-putting.

The question is whether the intensity is discussed in the link. My point was that the discussion is more to do with the frequency of light than with intensity.

Yea I remember that discussion. I'm not sure if I'm entirely convinced, but there are so many studies in progress looking at this that I decided to try running Redshift on my desktop again.

I will say, it does seem to make it easier to fall asleep at night.

The mammalian visual system has been the predominant model system used in developmental neurobiology research for the past fiftyish years. It's generally known at this point that visual circuits pattern themselves according to input, and that visual systems fed from a constrained input domain lose the ability to meaningfully represent real-world input. We also know that computer displays show a very restricted subset of perceptual info, and also don't relate to other sensory modalities (like proprioception of head/eye movements to look at peripheral objects) which are important for maintaining an integrated environmental map. So, it's more reasonable to assume that looking at monitors is harmful than helpful, especially at a young age (or following a stroke, taking certain HDAC6 inhibitors or other things that increase "neural plasticity"). The common knowledge of developmental neurobiology has advanced to the point where the claim "closer to natural ISN'T better for normal development" is one which requires proof.

Now, does this have any meaningful bearing on e-ink displays? The contrast ratio is closer to stuff you get in the natural world, but apart from that it's still a monitor.

Everything you said sounds really impressive, but

>visual systems fed from a constrained input domain lose the ability to meaningfully represent real-world input.

Seems to imply that looking at a computer monitor for too much of your life means you won't be able to see the real world, or not "see it right", whatever that means.

The only example of that I've seen is some people (kids, presumably) commenting on the Nvidia RTX demo videos that the non-raytraced versions, which lack real world lighting dynamics, look "better" than the raytraced ones, which were, to me at least, obviously closer to physically realistic, representative images. Now, whether they were saying that because their eyes have literally programmed themselves for cheaply rendered video game worlds, or because they didn't want to face spending the asking price of the RTX hardware, is up to the reader.

To add an anecdote from my adolescence: When I was 12-15 I spent pretty much all my time indoors, playing PC games or learning how to code. I realized I hadn't visited the river I was living basically next to for atleast two years when I had to pick something up at a booth next to it. I realized there that I found the water in Star Wars Galaxies much more "realistic" than the actual river flowing by. This freaked me out so much that I took a week off of gaming and went to take walks for a week.

I need to wear glasses with my retina display, but not with my e-ink reader. The eyes are definitely doing more work when looking at a backlit display for whatever reason.

Same distance, same text size, and same font?

also, same color scheme? I've seen some studies that show it's harder for people with certain vision issues to focus on text that's white text on a black background than it is for them to focus on black text on a white background, so.. if they're trying to read on a dark theme on their phone, that could be noticeably different from using their E-Ink screen, which is almost certainly using a light theme.

That would definitely be a good experiment to try. I would have to try a light black on light grey to match the kindle.

You get a LOT more light from a backlight than from reflection, at least in indoor conditions.

I can turn my monitor down so it's dimmer than a sheet of white paper on my desk. If I aim a desk lamp directly at the paper I can make it brighter than the monitor on full brightness. There's no standard brightness for monitor or paper.

But can you actually READ your monitor when it’s dimmer than a sheet of paper in ambient light?

If the contrast of the text is high enough, yes. For many websites this means custom CSS to disable the gray font color, but I do that anyway.

why does it have to be dimmer than ambient?

Not much. I can't read those trendy gray on white web sites too.

What you're missing is that your eyes adjust the amount of light they let in and their sensitivity relative to ambient light, which can often result in a monitor having "inappropriate" brightness levels relative to that level. Nobody on the planet spends all day constantly adjusting their monitors' brightness and contrast levels, even assuming that it was possible to reach the appropriate levels in all ambient lighting conditions within the range of those controls (hint: it's not).

On the other hand, passive displays (books, e-ink) by their nature inherently match ambient lighting conditions, because they simply reflect ambient light. This is the equivalent of a monitor with a much wider range of contrast and brightness levels equipped with an automatic adaptive adjustment with sub-nanosecond response times, something that simply does not exist with present technology.

So yes, in theory a monitor could potentially match a passive display in terms of reducing eye strain and tiredness but in practice it is beyond the state of the art for now.

That's just a function of monitor brightness, it has no connection to whether the light was reflected or not.

If a monitor has bad contrast and you turn up the brightness, that's not the fault of the light source. That monitor still won't even come close to the amount of blue light that a blue sky emits, even at maximum brightness.

Personally, I think all monitors made in the last 10 years should be as legible at low brightness as a piece of paper is in an equally poorly lit room.

It's ironic that this advice is written on a website with an 0xFFFFFF brilliant white background.

Edit: thank you, Dark Reader[0]

[0]https://darkreader.org/

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