



Pixel Density Comparison


Subpixel Density Comparison


Source: Data



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  • solarein - Wednesday, October 26, 2011 - link

    This is a ridiculously convoluted way of doing a very simple calculation. What you are doing is just calculating the number of RGB-equivalent pixels of the Galaxy Nexus, then diving that by the area and taking the square root to get the RGB-equivalent pixel per inch of the phone. What you could have done is simply calculate the dimensions of the Galaxy Nexus screen using the diagonal and the aspect ratio, and get 4.05in X 2.28in, and then do:
    sqrt(1280*720*(2/3) / (4.05*2.28)) = 257.9 RGB-equivalent pixels per inch, which you got.

    What you also don't realize is that this number prove the numbers in your second graph to be incorrect. You can get from the number of RGB-equivalent pixels per inch to the number of subpixels per inch by multiplying by sqrt(3) (because the square of sqrt(3) is 3, which is the ratio of subpixels to pixels per square inch of screen). For the Galaxy Nexus you get

    257.9*sqrt(3) = 446.7

    And for the iPhone 4 you get

    329.7*sqrt(3) = 571.1

    These are the correct numbers for the subpixel per inch of each phone. Notice that in this case you use sqrt(3) for the Pentile screen, not sqrt(2) because the 257.9 is the RGB-equivalent number of pixels per inch. If you use the actual number of pixels per inch, 315, then you multiply by sqrt(2) instead to get the subpixels per inch, and you still end up with 446.7.
  • solarein - Wednesday, October 26, 2011 - link

    An even simpler way of thinking about this is by noticing that, since the Pentile screen has 2/3 the number of subpixels as the RGB screen, you can pretend that in each dimension it has sqrt(2/3) the number of pixels, so that when you take the area you end up with 2/3 the number of pixels, which is what you want. Once you have this, converting from the pentile PPI to the RGB equivalent PPI is as simple as multiplying by sqrt(2/3). Reply

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