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dwaltz · 04-07-2017, 05:41 AM

The absolute number of DPI is not the correct number to use to determine readability.
The correct number is the viewing angle subtended by the pixel size.
That is determined by the combination of the pixel size (or DPI, aka density of pixel) and by the distance.

Another way to put it that I like is to ask: given a DPI at what distance it becomes a retina level?
And the answer is not "150" or "300" or any single DPI number, is the pair: DPI and distance.

You can use this retina calculator to do the math.

But given that we are talking about a 13.3" screen with 1600x1200 vs 2200x1650: the first 150 DPI and is retina at 58 cm (23") distance, while the second is 207 DPI and is retina at 43 cm (17").

So not perfect, but 43 cm for me is close to where I would place a screen of that size, while 58 cm is clearly a bit too far, hence I do appreciate the extra resolution.

Comparing this DPIs to your experience with tablets and phones is misleading unless you keep distance into account: the iPhone 7 is 4.7" and is 1344x750 and is retina at about 28 cm (11"), and nobody (or few) complain about its resolution, But for sure you don't consider reading an eReader 13.3" wide at the same distance at which you hold a smartphone.

04-07-2017, 05:41 AM	#22
dwaltz Junior Member Posts: 3 Karma: 2070024 Join Date: Jan 2011 Device: Pocketbook 902, Kobo Glo HD	The absolute number of DPI is not the correct number to use to determine readability. The correct number is the viewing angle subtended by the pixel size. That is determined by the combination of the pixel size (or DPI, aka density of pixel) and by the distance. Another way to put it that I like is to ask: given a DPI at what distance it becomes a retina level? And the answer is not "150" or "300" or any single DPI number, is the pair: DPI and distance. You can use this retina calculator to do the math. But given that we are talking about a 13.3" screen with 1600x1200 vs 2200x1650: the first 150 DPI and is retina at 58 cm (23") distance, while the second is 207 DPI and is retina at 43 cm (17"). So not perfect, but 43 cm for me is close to where I would place a screen of that size, while 58 cm is clearly a bit too far, hence I do appreciate the extra resolution. Comparing this DPIs to your experience with tablets and phones is misleading unless you keep distance into account: the iPhone 7 is 4.7" and is 1344x750 and is retina at about 28 cm (11"), and nobody (or few) complain about its resolution, But for sure you don't consider reading an eReader 13.3" wide at the same distance at which you hold a smartphone. Last edited by dwaltz; 04-07-2017 at 05:48 AM.