Libra 2 Page refresh - what is it and what should it be set to?

[rrr]

Page refresh - what is it and what should it be set to?
I have been going through all the settings and found page refresh.
What is it for?
What does it do?
What should I set it to?

[Sirtel]

It is the full refresh of the page. Usually, when you turn the page, it's partial refresh, which is faster, but in the long run will decrease contrast. The full refresh restores that lost contrast, but is slower.

So it depends on your preferences - if the speed of page-turns is more important to you, set the full refresh less often; if the best possible contrast and sharpness is more important, set it more often. Personally, I've set it to every page, but I'm an exception - most people value speed over contrast.

[JSWolf]

Originally Posted by Sirtel

It is the full refresh of the page. Usually, when you turn the page, it's partial refresh, which is faster, but in the long run will decrease contrast. The full refresh restores that lost contrast, but is slower.

So it depends on your preferences - if the speed of page-turns is more important to you, set the full refresh less often; if the best possible contrast and sharpness is more important, set it more often. Personally, I've set it to every page, but I'm an exception - most people value speed over contrast.

I don't find the contrast drops enough to be noticeable.

[Sirtel]

Originally Posted by JSWolf

I don't find the contrast drops enough to be noticeable.

Some people notice, some don't.

[Apollyon202]

I've put some huge number in the config files, like 500 or something, now it says "None selected".
Most of the time I can't read that many pages in one session, so after a couple dozen or hundred pages I close the cover. Later, when I open the cover and turn the first page, it does a full refresh anyway, so I’ve never seen ghosting get to an annoying level.

[Sirtel]

Originally Posted by Apollyon202

I've put some huge number in the config files, like 500 or something, now it says "None selected".
Most of the time I can't read that many pages in one session, so after a couple dozen or hundred pages I close the cover. Later, when I open the cover and turn the first page, it does a full refresh anyway, so I’ve never seen ghosting get to an annoying level.

It's not ghosting, it's decreasing in contrast - the text gets less dark with a number of partial refreshes. Many people are unable to see this for some reason, but some of us do see it (I know I'm not the only member of MR to notice the phenomenon).

[Apollyon202]

Originally Posted by Sirtel

It's not ghosting, it's decreasing in contrast - the text gets less dark with a number of partial refreshes. Many people are unable to see this for some reason, but some of us do see it (I know I'm not the only member of MR to notice the phenomenon).

I haven't noticed that on my Libra 2 but you could be right. I do remember that on my old kobos the page refresh was a must, but not on the Libra.

[Aleron Ives]

Originally Posted by Apollyon202

I've put some huge number in the config files, like 500 or something, now it says "None selected".

Hm, I thought the maximum was 90 or 99. I didn't know you could go higher than that.

[rrr]

i saw "grin through" - very pale text in the background - so I tried various settings and now am using 5.

[Sirtel]

Originally Posted by Apollyon202

I haven't noticed that on my Libra 2 but you could be right. I do remember that on my old kobos the page refresh was a must, but not on the Libra.

For me it's a must on any ereader, even the Libra. But as I said, I'm an exception. Most folks are perfectly happy to have the full refresh on seldom or even never. I have to have it on every page, or the lessening contrast starts to bother me pretty quickly.

[Sirtel]

Originally Posted by rrr

i saw "grin through" - very pale text in the background - so I tried various settings and now am using 5.

That's ghosting. And yes, full refresh helps with that too.

[Quoth]

Originally Posted by Sirtel

It's not ghosting, it's decreasing in contrast - the text gets less dark with a number of partial refreshes. Many people are unable to see this for some reason, but some of us do see it (I know I'm not the only member of MR to notice the phenomenon).

It also varies with model of eink panel and ereader model. Also unlike CRT, LCD, OLED, etc the panels are not identical and even have a calibration factor.

[Sirtel]

Originally Posted by Quoth

It also varies with model of eink panel and ereader model. Also unlike CRT, LCD, OLED, etc the panels are not identical and even have a calibration factor.

No, it doesn't. The lessening contrast happens on every eink device. (As I said, I don't mean ghosting, which indeed varies between different devices).

[Aleron Ives]

Isn't it the same thing? If you don't do a full refresh, cells will be unable to fully transition to black or white, and you'll end up with cells that are some shade of grey, i.e. lower contrast. In extreme cases this will preserve content between pages instead of clearing it, which is called ghosting, but the phenomenon is always present to some extent, unless you do a full refresh on every page.

[Sirtel]

Originally Posted by Aleron Ives

Isn't it the same thing? If you don't do a full refresh, cells will be unable to fully transition to black or white, and you'll end up with cells that are some shade of grey, i.e. lower contrast. In extreme cases this will preserve content between pages instead of clearing it, which is called ghosting, but the phenomenon is always present to some extent, unless you do a full refresh on every page.

I don't know if there is a technical difference. Ghosting varies between eink screens - on some devices it's more noticeable than others. The text growing paler happens on every device (I think I can say this with some certainty, having owned and used 11 different eink models), it's just that some devices have better contrast (blacker blacks) to begin with, and so the decreasing contrast may also be less noticeable. The contrast does always grow less with partial refresh, though - I haven't seen an eink screen where this doesn't happen. It's inherent in the current eink technology.

Why some people claim to never see it even with no full refresh on at all, I don't know.