Integer scaling vs pixel density on different macbook models

[Silicium]

Hi All

"People" say that if you want to run a external monitor on a Macbook and if you want to use integer scaling you need a screen with a pixel density of 220 dpi and my question is: why?

I mean the pixel density varies over the products (macbooks), that would either mean that apple fixing their external screen thing to 220 which is technically not necessary or you need a different screen for another macbook (could be technically a reason but if so it would be a super stupid implementation.

So, why exact problem do people have with a 4K screen? is the issue that they want to get more estate than 1080p but not too small UI?

 

[galad]

Right, the macOS can be rendered only at 1x or 2x. The various "scaled" resolutions are just the UI rendered at 2x, and the resized after rendering, so it look as good.

 

[gilby101]

"People" say that if you want to run a external monitor on a Macbook and if you want to use integer scaling you need a screen with a pixel density of around 220 dpi and my question is: why?

"Retina" quality at usual distance of external monitor from eye requires around 220 dpi. Retina quality being defined by a person with 20/20 vision (some people have better than that) being unable to see individual pixels - or something like that.

2x scaling and 220ppi makes text look the "right" (or standard) size. So text being the right size with no blurring requires integer scaling.

So there are three things leading to 2x and 220 ppi:
1) Retina quality;
2) Text size;
3) Best clarity - minimum blurriness.

MacBooks usually have higher ppi, because the eye is closer to the screen.

4K and, for example, 27" requires non integer scaling to get text standard size and this the leads to blurring as well as not up to Retina quality. 4K and about 23" with 2x scaling gives the standard size text with no blurring. 4K screens bigger than 23" are typically used with not ideal blurring and/or text size - but the user may be happy with that compromise.

 

[Basic75]

"People" say that if you want to run a external monitor on a Macbook and if you want to use integer scaling you need a screen with a pixel density of 220 dpi and my question is: why?

There are two options for integer scaling, 110 ppi where 1 layout pixel corresponds to 1 actual pixel, or 220 ppi for "retina" where 1 layout pixel uses 2x2 = 4 actual pixels.

I mean the pixel density varies over the products (macbooks), that would either mean that apple fixing their external screen thing to 220 which is technically not necessary or you need a different screen for another macbook (could be technically a reason but if so it would be a super stupid implementation.

Apple has often supported slightly higher resolutions on laptops because people sit closer to them, and because it's not so easy to just add another display when on the move.

So, why exact problem do people have with a 4K screen? is the issue that they want to get more estate than 1080p but not too small UI?

Please, this entire discussion is about pixel densities, so you can't speak about "a 4K screen" without specifying the size!

If you have a 43 inch 4K display you can comfortably run it at @1x like in the pre-retina days where you're running a 1:1 mapping and everything will have the correct size.

If you have a 21 inch 4K display you can comfortably run it at @2x retina resolution giving you FHD real estate but looking much nicer.

If you have a 27 inch (or 32 inch) 4K display you have to choose between three non-optimal standard possibilities, @1x everythign will be much smaller than usual, @2x it will be much larger, and with a size-appropriate resolution you lose integer scaling and gain some overhead due to the indirect rendering.