White Text on Black Background

[Farmer]

White and black are perfectly reasonable terms - I think most here understand the threshold at which grey becomes either black or white for general discussion.

Overall, reducing the contrast between the text, the background and the ambient light levels.  The key here is ambient light levels.  If you're reading in a darkened room at night, then a black background is usually very good, so long as the text isn't too bright, but in a lit office, for example, as I've demonstrated the contrast between the screen average and the ambient light is greater and that is likely to cause more strain.

To answer your question, I wouldn't use a 400cdm^2 monitor - no matter what, I'd turn it down (calibration is not the point).  I *might* decide it was useful if I was trying to see something in bright sunshine I suppose, but more likely I'd try to shade the monitor and turn it down.  In other words, I find that level of brightness too contrasted to any reasonable ambient light level I'm likely to encounter in normal events.

I'm talking about average environments in which people work and have reasonable lighting levels (200lx to 400lx).

[Ray]

White and black are perfectly reasonable terms - I think most here understand the threshold at which grey becomes either black or white for general discussion.

Are you sure? Consider the attached image which I concocted in Photoshop. The grey text looks sort of whitish to me, and certainly whiter than the grey background surrounding the black square. But actually the text isn't whiter than the grey background. Both the text and the outer grey background have the same RGB values of 150,150,150, which I would describe as slightly paler than a medium grey.

Overall, reducing the contrast between the text, the background and the ambient light levels.  The key here is ambient light levels.  If you're reading in a darkened room at night, then a black background is usually very good, so long as the text isn't too bright, but in a lit office, for example, as I've demonstrated the contrast between the screen average and the ambient light is greater and that is likely to cause more strain.

No argument here. I admit there are a number of contributing factors to eye strain.

To answer your question, I wouldn't use a 400cdm^2 monitor - no matter what, I'd turn it down (calibration is not the point).  I *might* decide it was useful if I was trying to see something in bright sunshine I suppose, but more likely I'd try to shade the monitor and turn it down.  In other words, I find that level of brightness too contrasted to any reasonable ambient light level I'm likely to encounter in normal events.

As I already mentioned, you're very sensible . But what about others? There are billions of people in the world, many getting a computer for the first time, and many who do not have much clue after using a computer for many years.

I'm talking about average environments in which people work and have reasonable lighting levels (200lx to 400lx).

Can you provide some statistics on world-wide average environments involving computer monitors? I get the impression you might think the world is a more reasonable and well-organised place than it actually is.

[Farmer]

I can tell you that it's easy enough to find average office lighting level standards - Google will do it for you.  We can't examine every possible case - clearly if we consider the partipants of this site who are involved in the discussion, it's mainly western cultures (numerous exceptions, but that's the majority).

If the discussion heads toward the minutae of semantics for the sake of them, it's pointless.

It's not unlike your grey/white/black query.  Most folks have probably seen the graphics of the illusion of colours.  To answer your question, though, yes I'm quite sure most people on a photographic website have enough of a graps to make reasonable decisions about where black and white come into being on the grey scale for the purpose of the discussion at hand.

For those who use monitors at brightness levels that I consider absurd (and that includes at least one extremely well known photo book author), that's up to them.  I can only suggest better options, I can't enforce them (well, at work I can, but that's a different story).

[Ray]

I can tell you that it's easy enough to find average office lighting level standards - Google will do it for you.  We can't examine every possible case - clearly if we consider the partipants of this site who are involved in the discussion, it's mainly western cultures (numerous exceptions, but that's the majority).

Standards are one thing. Implementation of such standards are often a different thing, and from my personal experience, I would say sometimes an extraordinarily and extremely different thing.

By the way, I'm disappointed you didn't correct my paragraph on the black background. I should have written, "because less light is transmitted from the words."

[Farmer]

I didn't think that you meant reflected, so I didn't see the point in "correcting" you.  Clearly you understand the mechanism involved :-)