Pixel Density is the measure of how many pixels fit into a certain area. Pixels Per Inch (PPI) is used to describe the resolution of a display, it is normally referred to as pixels per inch. It’s not always an indicator of how good the screen will look but also depends on other factors such as screen size and viewing distance. For example, an image viewed from a foot away would look sharper and better defined on a screen with 250 pixels per inch (PPI) than it would on a 300 PPI screen because your eyes wouldn’t be able to discern the difference. The pixels on the lower resolution screen would appear larger and better defined. However, if you backed away from that same phone about twice as far – then it wouldn’t matter because your eyes wouldn’t be able to discern the individual pixels even on the 300 PPI screen.
Considerations for Pixel Density / Pixels Per Inch (PPI)
There are two main factors to consider when choosing a screen with regard to pixel density: – viewing distance and physical size of the screen. If you sit closer to your smartphone or tablet then higher resolution displays will make images and text look better because the pixels will be more defined and sharper. However, if you sit further away (for example, if you are using your phone as a portable device) then the pixels will not be visible even on very high pixel density screens.
The same is true for tablets, lots of people hold them closer to their eyes than phones so they would benefit from higher density displays. Some other considerations include battery life and GPU performance – higher resolution means more work for the processor and more battery drain.
Reading Mode / Night Mode for Pixel Density / Pixels Per Inch (PPI)
There are plenty of apps that allow you to tweak pixels density, one example is “reading mode” which uses slightly different colors to increase the contrast between text and background – because it’s using a lower resolution than normal, to save battery and resources.
On the other hand, there is a “night mode” which uses a resolution that is slightly larger than others – this allows for better contrast and sharpness when viewing the screen at an angle (the higher pixel density will make up for the fact it’s not 100% accurate). On many high-end smartphones, there are different modes (usually “Dynamic”, “Standard” and “Natural”) which can also be tweaked to suit personal preferences.
Pixel Density vs Screen Size
The reason pixel density is talked about with screens today is because current smartphone resolutions top out at around 400PPI (Apple iPhone 5), meaning anything over that would need a bigger screen to make it noticeable. In fact, you would need a 27″ monitor with a resolution of 2560 x 1440 – which is what we use for testing purposes and the reason we test at that resolution. This is why Apple made such big news about their “Retina Displays”, because anything over 300 PPI on a phone-sized screen would be pointless and a waste of battery and system resources for the user.
Larger screens allow you to sit further away from the screen, meaning that lower pixel density does not affect the experience because your eyes can’t tell the difference between individual pixels even on high-resolution screens such as that of the iPhone 6. This is why we test screens at their standard size (for example, 5″ or 10″) – it means we get more “real world” results rather than numbers on a paper – what matters is how good images look in person.
Apple took things one step further and made sure everything on-screen was rendered perfectly (including icons and other UI elements) by implementing their patented “Retina Displays”. This involved adding extra pixels to the screens of their devices – Apple did not make the screens bigger or add more pixels, they simply added more pixels within existing screen space.