Libra 2 About reolution ratio, why not exactly 4:3?

marineB · 11-19-2022, 06:36 PM

Isn't that supposed to have 4:3 ratio for the display, 1680 * 1260 px for 7" eReaders? Why does Libra2 have 1680 * 1264 px? Is there any reason for 4 more pixel vetical lines?

Aleron Ives · 11-19-2022, 07:50 PM

It's probably because 1264 is a multiple of 16. Most video compression techiques divide images into 16x16 squares, so displays tend to be multiples of 16 pixels. Although an e-reader isn't used for watching video, it's probably more efficient for things like image scaling when you're looking at book covers full screen. It may also be more efficient for the factory to produce the display panels that way.

marineB · 11-19-2022, 10:07 PM

Quote:

Originally Posted by Aleron Ives

It's probably because 1264 is a multiple of 16. Most video compression techiques divide images into 16x16 squares, so displays tend to be multiples of 16 pixels. Although an e-reader isn't used for watching video, it's probably more efficient for things like image scaling when you're looking at book covers full screen. It may also be more efficient for the factory to produce the display panels that way.

Thank you for your answer.
Divide by 16.
That explains 7", 8" eReaders
7" - 1680px : 1264px
1264/16= 79
8" - 1920px : 1440px
1440/16= 90

But in case of 6", 6.8", 7.8" eReaders;
There's still problem.

6" - 1440px : 1080px
1080/16= 67.5

6.8" - 1648px : 1236px
1236/16= 77.25

7.8" - 1872px : 1404px
1404/16= 87.75

marineB · 11-20-2022, 02:23 AM

Quote:

Originally Posted by Aleron Ives

It's probably because 1264 is a multiple of 16. Most video compression techiques divide images into 16x16 squares, so displays tend to be multiples of 16 pixels. Although an e-reader isn't used for watching video, it's probably more efficient for things like image scaling when you're looking at book covers full screen. It may also be more efficient for the factory to produce the display panels that way.

That explains 7" and 8" eReaders. But what about 6" width 1080px, 6.8" width 1236px, 7.8" 1404px? The width of hese eReaders can not be divided by 16.

Quoth · 11-20-2022, 12:27 PM

Quote:

Originally Posted by Aleron Ives

It's probably because 1264 is a multiple of 16. Most video compression techiques divide images into 16x16 squares, so displays tend to be multiples of 16 pixels. Although an e-reader isn't used for watching video, it's probably more efficient for things like image scaling when you're looking at book covers full screen. It may also be more efficient for the factory to produce the display panels that way.

Also to do with addressing, transfer and how the driver chips work, not just video.

11-19-2022, 06:36 PM	#1
marineB Junior Member Posts: 5 Karma: 10 Join Date: Oct 2022 Location: South Korea Device: Kobo Sage, Boox Leaf2, Boox Note2, Boyue P78, Hisense A7, Paperwhite	About reolution ratio, why not exactly 4:3? Isn't that supposed to have 4:3 ratio for the display, 1680 * 1260 px for 7" eReaders? Why does Libra2 have 1680 * 1264 px? Is there any reason for 4 more pixel vetical lines?

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11-19-2022, 07:50 PM	#2
Aleron Ives Wizard Posts: 1,689 Karma: 16307824 Join Date: Sep 2022 Device: Kobo Libra 2	It's probably because 1264 is a multiple of 16. Most video compression techiques divide images into 16x16 squares, so displays tend to be multiples of 16 pixels. Although an e-reader isn't used for watching video, it's probably more efficient for things like image scaling when you're looking at book covers full screen. It may also be more efficient for the factory to produce the display panels that way.