Is very high contrast really a good thing?

[Ariadne]

I'm attempting to decide which reader to buy and, as I can't find anywhere nearby (Brussels, Belgium) to go and look at different models, I'm reading all I can about them. I keep coming across comments about contrast and the lack of it.

I don't suppose anyone's done any proper research - by which I mean testing as opposed to asking people what they prefer - on the displays of these devices. I do know, though, that what people prefer isn't necessarily what's best. An example:

In a piece of research into on-screen legibility of serif versus sans-serif fonts, most subjects preferred the sans-serif and thought it clearer and more legible. But when tested most performed better with the serif font.

That testing was on legibility, which I'd define as the ability to discriminate detail - essential for telling the difference between similar characters like 3 and 8.

There's also readability, which I think concerns comfort level of prolonged reading. I know that I find sustained reading more comfortable if the paper isn't high-white but book-white (pale cream, if you like).

Thoughts, anyone? (I don't expect facts, but if anyone has any of those to share I'd be delighted. )

[Ea]

If it's e-ink screen you're thinking about, then it's a great deal more like paper than backlighted screens - it's not like "screen reading" is commonly understood so I'm not sure the same "rules" will apply to e-ink.

At the moment, the e-ink screens used have very dark (almost black) text on a light grey background - not quite as a white as good quality paper.

[igorsk]

Originally Posted by Ariadne

I'm attempting to decide which reader to buy and, as I can't find anywhere nearby (Brussels, Belgium) to go and look at different models, I'm reading all I can about them. I keep coming across comments about contrast and the lack of it.

You can visit Netherlands to see a Sony Reader - just find an ANWB shop near the border. Or if you're up for a quick trip to Liege I can show you my collection.

[zelda_pinwheel]

Originally Posted by igorsk

You can visit Netherlands to see a Sony Reader - just find an ANWB shop near the border. Or if you're up for a quick trip to Liege I can show you my collection.

ariadne, if you can manage a trip to liège, i would definitely accept igorsk's generous offer ; you'll never find a shop with so many different models, all in good working order for demonstrations.

[LDBoblo]

It's pretty common for typographers to distinguish legibility and readability, as they have done for many many years.

Not sure why that's immediately relevant to contrast on e-ink screens.

Extremely high contrast is vague and on reflective screens, is constrained by a few factors. On a global level (meaning full black versus full white), e-ink could try to increase the overall surface reflectivity (which would make the "white" whiter, but the black grayer), it could try to reduce the reflectivity of the black particles (making the "blacks" darker, which could be good since they are nowhere near ink black except in low-light, much closer to dark pencil gray).

They could also improve the dynamic range, which allows more fine-tuned font smoothing and anti-aliasing, which increases local contrast significantly (in practice most fonts are never full-black on e-ink since significant areas of the letterforms are faded to a gray to improve perceived clarity and reduce pixellation). These things actually make e-ink's blacks, which are not very strong in the first place, even weaker.

As far whether or not there's a practical limit to contrast improvement, I think most casual observers would think so. Trying to read bleach-white paper in bright sunshine is a great way to get a horrible headache, though it can be a godsend in less optimal lighting conditions.

When people like me say we want more contrast, we generally mean that in mediocre lighting conditions where a cheap paperback is still readable, e-ink struggles to reflect enough light to remain readable; and some fonts at normal reading sizes, and for me especially in more visually-complex character sets like Chinese, many characters exhibit such low local contrast due to the weak black and heavy-handed font smoothing that their illegibility actually becomes conspicuous enough to interfere with reading. Thus, I've had to typeset most of my Chinese books in heavyweight sans-serif fonts which I dislike due to their mediocre readability and general visual appeal. I need to also typeset my English novels in heavier, lower serif-contrast "caption" sized fonts, of which some of my collection still only barely work due to the presence of more oblique lines that conflict with the pixel map.

I don't think electronic paper will come anywhere near a contrast level that could be considered "excessive" in quite some years. It currently is still a few steps behind even my cheapest paperback paper/ink combos (my cheapest are Terry Pratchett's books published by Harper) in pretty much any light. I've seen some faintly printed inks though that can give e-ink a run for its money in the illegibility department. I just won't buy books like that.

Addendum: When I wrote this, I must have been intensely sleep-deprived because on rereading it barely makes any sense. I'll have to rewrite it sometime...

[Jack Tingle]

From what I know (admittedly limited) the answer is likely yes.

Printed books and papers have contrast ratios of 10-40:1. That means that the paper has on the order of 50-90% reflectance, and the ink as applied to the page has 1-10% reflectance. Think of the worst aged newsprint you've ever seen vs. National Geographic's best page. That's the range of 10-40:1.

As you noted, high reflectance paper can be a pain in very bright conditions, but otherwise, high contrast is usually easier to read.

The next best reflective display in ebooks, the one in the Ectaco jetBook has a 12:1 contrast. The black is very black, so it's likely that's an overall reflectance in the light areas of 20-50% or so. The fundamental technology is such that overall reflectance can't exceed t^2*r(background)[1], and I doubt you can get much better than 60-70% under any circumstances. This display is tolerably readable under dim-ish lamp light. (Mother: "Why are you reading in the dark. Turn on some light; you'll ruin your eyes!") I can vouch for the fact that you're in no danger of discomfort, even in full sunlight.

eInk displays have 7-8:1 contrasts, with dark gray letters on a light gray background. They are reasonably legible, except by dim-ish lamp light. (Mother: same comment.) If you typically read in sensible conditions, or in full sun, you shouldn't have any problems. Some displays apparently don't sufficiently immobilize the pigments in the electrophoretic cells when they get hot, as in full sunlight. Those can dim and wash out in bright sunlight.

[1] t=transmissivity; r=reflectance; if both equal 90% you get 73% or so.

Regards,
Jack Tingle

[Lemurion]

Another thing to consider is the infamous number of gray scales factor. A greater number of gray scales does not mean the darkest text is darker, it simply means a greater number of intermediate steps.

More gray scales improve readability by allowing for better anti-aliasing, however where they really shine is in the display of images.

The best thing for anyone to do is find a place where you can see multiple devices and just take a look. See what the screen looks like and go from there.

[brecklundin]

for easier readability look for the ability of the reader device to "embolden" the fonts installed. This is sorta like making the font bold, but, not...I know the Pocketbook 360 has this ability and not sure which other readers can do this.

From what I have seen, this can make up for the poorly chosen font weights used as the default. In it's simplest terms it makes the effective contrast ratio to be better than it is in reality. On the 360 to my eye it makes the text look cleaner and definitely not washed out as my K1 even when set to bold. Not sure if the Opus provides a similar feature to that found on the Pocketbook readers.

Overall, eink still is struggling to actually provide a true analog to reading on paper.

[Ariadne]

Wow! I didn't expect such a rapid and excellent set of responses. Even some facts.

everyone.

OK - I'll put my cards on the table: I'm deeply attracted to the Sony PRS-600, because

• a 6" screen seems about right
• overall size & weight is good
• it supports a fair range of formats
• it has annotation & search facilities
• it is compatible with Mac, and, I'll be honest
• the design is beautiful.

It's about the most expensive I could afford, though I can see that I might in time be tempted to add the cover with a built-in light.

So I've been trying to convince myself that the common complaint about lack of screen contrast could work to my advantage (I plan to use it for reading novels).

Igorsk - thank you so much for your kind offer! Liège is a bit far but if I get any more conflustered I might take you up on it.

Off to brood about the whole issue for a bit.