Pocketbook touch lux 3: black characters too gray

giotti · 12-15-2020, 12:14 PM

Hello, I noticed that in some books, after turning a page, fonts are displayed black for a short time and then they shade a little gray, both with the default reader and with koreader.
I am on firmware 5.20.
Is there a way to make them stay full black?

Thanks.

ReaLx3m · 12-17-2020, 07:33 PM

try increasing contrast , its in the bottom menu on Koreader

EastEriq · 12-18-2020, 03:51 AM

I think it is unavoidable given how eink works, and how the desired level of black is achieved by opportunely cycling the driving level of the pixels to be repainted (the "waveform", which is individually tuned for each display). Most likely the amount of ghosting, or of partial washout you observe, is related to the amount of black and white you had on the same spot on the previous few pages.
The cure to the problem is to force frequently a full page refresh. There are settings for that both in the PB OS and in KR. That increases significantly battery use though.
Increasing font contrast in KR, as ReaLx3m suggests, may also have some effect because overall more black on page causes more level changes.

giotti · 12-18-2020, 06:45 AM

Thanks for the informations.

Indeed, partial washout explains better my "problem".

I tried to enhance the contrast, with some improvement.
Refresh the screen also helps, but not completely.

It is difficult to render the problem in pictures... anyway, I attach two pictures in order to show the difference:
* contrast 2: a book that shows good;
* contrast 5: a book that has the problem.

A short video I also tries to show the washout.

As @EastEriq says there is probably nothing more to do. I just wanted to make the post more meaningful.

Best regards.

nhedgehog · 12-18-2020, 10:33 AM

I saw your video, it looks like those books are pdf and you are not using reflow. Is that true?

giotti · 12-19-2020, 05:29 AM

No, it is epub.

nhedgehog · 12-19-2020, 04:37 PM

Combining this information with what you wrote on your first post:
This effect is happening on some epub books and on other epubs not.
If so, having the epubs to analyse the problem is mandatory.

giotti · 12-20-2020, 09:40 AM

I will provide a minimal working example asap.
Thanks.

12-15-2020, 12:14 PM	#1
giotti Connoisseur Posts: 52 Karma: 2030 Join Date: Sep 2018 Device: Wexler flex.one, Boyue T65s, Pocketbook Touch Lux 3	Pocketbook touch lux 3: black characters too gray Hello, I noticed that in some books, after turning a page, fonts are displayed black for a short time and then they shade a little gray, both with the default reader and with koreader. I am on firmware 5.20. Is there a way to make them stay full black? Thanks.

12-19-2020, 04:37 PM	#7
nhedgehog Guru Posts: 746 Karma: 619508 Join Date: Sep 2013 Device: EnergySistemEreaderPro, Nook STG, Pocketbook 622, Bookeen Cybooks ...	Combining this information with what you wrote on your first post: This effect is happening on some epub books and on other epubs not. If so, having the epubs to analyse the problem is mandatory. Last edited by nhedgehog; 12-19-2020 at 04:39 PM.

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12-17-2020, 07:33 PM	#2
ReaLx3m Groupie Posts: 154 Karma: 32060 Join Date: Aug 2017 Device: Kobo Aura H2O, Kobo Aura One, Pocketbook Inkpad 3 Pro	try increasing contrast , its in the bottom menu on Koreader

12-18-2020, 03:51 AM	#3
EastEriq Groupie Posts: 169 Karma: 100516 Join Date: Jan 2018 Device: Cybook Orizon, PocketBook Touch HD	I think it is unavoidable given how eink works, and how the desired level of black is achieved by opportunely cycling the driving level of the pixels to be repainted (the "waveform", which is individually tuned for each display). Most likely the amount of ghosting, or of partial washout you observe, is related to the amount of black and white you had on the same spot on the previous few pages. The cure to the problem is to force frequently a full page refresh. There are settings for that both in the PB OS and in KR. That increases significantly battery use though. Increasing font contrast in KR, as ReaLx3m suggests, may also have some effect because overall more black on page causes more level changes.

12-18-2020, 10:33 AM	#5
nhedgehog Guru Posts: 746 Karma: 619508 Join Date: Sep 2013 Device: EnergySistemEreaderPro, Nook STG, Pocketbook 622, Bookeen Cybooks ...	I saw your video, it looks like those books are pdf and you are not using reflow. Is that true?

12-19-2020, 05:29 AM	#6
giotti Connoisseur Posts: 52 Karma: 2030 Join Date: Sep 2018 Device: Wexler flex.one, Boyue T65s, Pocketbook Touch Lux 3	No, it is epub.

12-20-2020, 09:40 AM	#8
giotti Connoisseur Posts: 52 Karma: 2030 Join Date: Sep 2018 Device: Wexler flex.one, Boyue T65s, Pocketbook Touch Lux 3	I will provide a minimal working example asap. Thanks.

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