iPhone 8(+) True pixel density of Plus (401) > Max (373) > XR (326): Are these calculations correct?

Discussion in 'iPhone' started by EugW, Sep 18, 2018.

  1. EugW, Sep 18, 2018
    Last edited: Sep 18, 2018

    EugW macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #1
    For each iPhone 8 Plus and XR pixel, there are three subpixels. Each has red, green, and blue.
    For each iPhone XS Max pixel, there are two subpixels. Each has green, but they alternate between red and blue.

    For the iPhone 8 Plus, the 1920x1080 screen size is 5.5", or 4.79 x 2.70 inches = 12.933 inches squared.
    For the iPhone XS Max, the 2688x1242 screen size is 6.5", or 5.90 x 2.72 inches = 16.048 inches squared.
    For the iPhone XR, the 1792x828 screen is 6.1", or 5.54 x 2.56 inches = 14.18 inches squared.

    For the iPhone 8 Plus, there are 3x1920x1080 = 6220800 subpixels, or 481002 subpixels per square inch.
    For the iPhone XS Max, there are 2x2688x1242 = 6676992 subpixels, or 416064 subpixels per square inch.
    For the iPhone XR, there are 3x1792x828 = 4451328 subpixels, or 313916 subpixels per square inch.

    If we are to set a standard for pixel density with the iPhone 8 Plus as equal too 100%, it would be as follows:

    100% - iPhone 8 Plus
    86% - iPhone XS Max
    65% - iPhone XR

    Now, these are on the basis of two-dimensional measurements. If we were to calculate based on one-dimensional measurements, you have to take the square root of the difference in area pixel density. Once we do this, we get:

    401 ppi: iPhone 8 Plus (and also all other Plus iPhones)
    373 ppi: iPhone XS Max (and also XS and X)
    326 ppi: iPhone XR (and also 4, 4S, 5, 5C, 5S, SE, 6, 6s, 7, 8)
     
  2. Lobwedgephil macrumors 601

    Lobwedgephil

    Joined:
    Apr 7, 2012
    #2
    What are you saying the difference is between your

    XS and XS Max of 373 and Apples XS and XS Max of 458 ppi?
     
  3. EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #3
    The 458 ppi of the XS and XS Max is not accurate, at least when comparing to LCDs. It's based on Samsung's Diamond Pentile arrangement, but the key here is that each pixel only has 2 subpixels, whereas a true RGB LCD pixel has three subpixels. So the 458 ppi number for OLEDs is a cheat. What Samsung does is "borrow" a subpixel from the next pixel, to get your RGB colours.

    I just wanted to go through the calculations to determine what the real pixel density is on the OLEDs but in LCD terms. Now, some may argue you can't compare them directly this way since the subpixel arrangement is different, but on a base level I think you can.
     
  4. Lobwedgephil macrumors 601

    Lobwedgephil

    Joined:
    Apr 7, 2012
    #4
    Gotcha, just wasn't sure where you were going with this. Interesting. I haven't seen an XS, but I have an X and an 8+, and the display on the X is much better to me, but would seem to have a lower pixel density, but I am not sure you can compare two different display technologies like this. Interesting nonetheless.
     
  5. EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #5
    The OLEDs have MUCH better blacks and therefore better contrast, at least in a dark room. I find in a very bright room there isn't much difference, but in a dark room the OLED's advantage here would be obvious.

    On both the 401 ppi LCDs and the OLEDs, text is very clear, so I guess the true pixel density of the OLED is high enough. It's actually pretty good on the 326 ppi LCDs too but if you look for it, you can see softening around text edges, esp. with small fonts.

    OTOH, the OLED suffers some off-axis colour and contrast washout that isn't present on either the 401 ppi or 326 ppi LCDs. OLEDs can also suffer burn-in but this has been a complete non-issue with iPhones. Some people get headaches with the PWM flicker of Apple OLED iPhones though. I don't know for myself since I haven't used an Apple OLED iPhone for more than an hour at a time.
     
  6. profets macrumors 601

    Joined:
    Mar 18, 2009
    #6
    Good summary and breakdown of all the numbers.

    I've always been curious about resolutions, pixel density and was always aware of the sub pixel differences between OLED and LCD. I remember being overly excited when we first found out the iPhone 4 was doubling the pixel density from previous phone.

    I used both the 6/7 Plus and the 6s for a full year at a time. I could definitely notice a difference between the 4.7" 326ppi and the 5.5" 401ppi. On the Plus phones, to my eyes anyway, it really became tough to discern individual pixels, where I was more able easily able to on the 326ppi devices (and 264ppi iPads FWIW).

    On my iPhone X that I've been using since launch I've never been able to easily see individual pixels, even when looking very close at the display. I remember using Android phones in the past when 4.7" / 720p displays first became popular and the sub pixel arrangement was much more noticeable, but with the X, to me anyway I really can't tell nor has it bothered me at all.

    I do definitely notice the off-axis colour and contrast change/issue with the OLED screen though.
     
  7. Seige macrumors newbie

    Joined:
    Jan 30, 2012
    #7
    Hi,

    I am a bit confused by your calculations. Afaik, the way ppi is calculated has nothing to do with the respective subpixel design, it depends on the actual number of pixels displayed inside an inch of display:

    https://en.wikipedia.org/wiki/Pixel_density#Calculation_of_monitor_PPI

    If i calculate this for the XS Max I get:

    PPI=(sqrt(1242^2+2688^2))/6.5=455 ppi

    Dividing the horizontal resolution by the width or the vertical by the height of the display yields the same number.

    The number describes how many pixel in an inch, not inside the area of a square inch. Question4s is, am I missing something here or are you describing something else?

    Regards,
    Seige
     
  8. EugW, Sep 18, 2018
    Last edited: Sep 18, 2018

    EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #8
    A proper full pixel has three sub pixels. This is true for LCDs and it's true for Samsung OLEDs as well. However, Samsung's OLEDs only have 2 sub pixels per pixel. To compensate for this, they borrow a subpixel from an adjacent pixel.

    True pixel count is based on number of true pixels per square inch, but it is traditionally represented by a one-dimensional measurement. Therefore the change in pixel count increases by the square of the increase in numerical ppi value.

    Original iPhones had pixel density of 163 ppi. Then the iPhone 4 came along at 326 ppi. However, the true pixel count didn't double. It quadrupled.

    ---

    What I am doing here is counting the number of subpixels per square inch to calculate the count of true pixels (with 3 subpixels per true pixel), and using that number to come up with the true pixel count per square inch, and then in turn using that to calculate the comparative one-dimensional ppi.

    Thus, the Plus has 401 ppi, the XS and Max have about 370-375 ppi (error due to rounding), and the XR has 326 ppi.

    ---

    This does seem to have some support, because back in the day when people were pixel peeping and doing magnified photographs of these pentile OLEDs vs LCD, 401 ppi LCDs did actually show more detail than 458 ppi OLEDs. However, in real world usage, at least for text, they seem effectively identical, at least at reasonable viewing distances.
     
  9. Seige macrumors newbie

    Joined:
    Jan 30, 2012
    #9
    Thank you for clarifying that for me. Basically, you want to define a quantity that shows the actual/real world pixel density or "sharpness" of the display, independent of the technology used?!

    I agree that an OLED using a pentile style display appears less sharp than an LCD with the same advertised PPI side by side. But in my opinion the the density of the iPhone X next to the 8 Plus is already close enough, not to be an issue for me, even though I am picky. I do remember when Apple integrated the touch layer into the display. You could see a difference in sharpness in the first generation (5 or 5s?).
     
  10. EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #10
    Effectively yes. Most of us here know that the 458 ppi quoted by Apple cannot be directly compared against the 401 ppi for the Plus, yet a lot of other people take those numbers as gospel.

    I just wanted to go through the exercise of calculating the effective ppi myself from a technical perspective, to see how they compare, although I acknowledge that the architecture and pixel sizing may also increase perceived quality.

    And I want to make sure my calculations are correct.

    I agree. If I put the 7, 7 Plus, and X side by side on the table, and look at them from a reasonable viewing distance, the Plus and the X look equally sharp to me with text. However, I can appreciate a mild softness with the 7 (326 ppi).

    What does this tell me? Nothing absolutely conclusive except to say if Apple released a new LCD iPhone next year with say 375 ppi, it might be indistinguishable from the 401 ppi Plus at normal viewing distance. (Apple won't release that though I'm sure.)

    Interestingly though, when I just use the 7 on its own and don't have the 7 Plus and X beside it, it looks pretty good too. I guess that's why Apple has been able to continue to use 326 ppi screens for so long, and why they are releasing a new 326 ppi iPhone this year. The 7 has the same pixel density as the XR and 5/5S.
     
  11. JPack macrumors 601

    JPack

    Joined:
    Mar 27, 2017
    #11
    LCD pixels = RGB
    OLED pixels = RG or BG

    In quantitative terms, OLED iPhone has fewer subpixels than LCD iPhone. OLED doesn't magically increase sharpness with fewer subpixels.
     
  12. kasakka macrumors 68020

    Joined:
    Oct 25, 2008
    #12
    What's the goal with this thread?

    I have owned both the Oneplus One and currently have a Oneplus 3, both of which have 5.5" 16:9 1080p displays but the OP3 has an AMOLED and the One is an LCD. When I got the OP3 I compared it side by side with the One's display and I'll be damned if I could tell any significant difference in their sharpness. There was more difference in black depth, color accuracy and brightness. The display on the iPhone XS are probably a lot better than the one on my 2 year old Oneplus 3.
     
  13. profets macrumors 601

    Joined:
    Mar 18, 2009
    #13


    This is basically how I feel having used all these devices for ~1 year each.

    I agree, and also should mention the percentage of users who truly understand and appreciate these details like we do are probably a sliver of the whole user base.
     
  14. realeric macrumors 65816

    realeric

    Joined:
    Jun 19, 2009
    Location:
    United States
    #14
    It’s simple.

    iPhone XS Max = 305ppi (458 x 2/3)
    iPhone 8+, 7+ = 401ppi
    iPhone Xr, 8, 7, ... = 326ppi
     
  15. EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #15
    I don't think that's accurate, and it wouldn't make sense since up close the X is noticeably sharper than the 7.
     
  16. outphase84 macrumors newbie

    Joined:
    Sep 21, 2018
    #16
    Your argument is based on a number of incorrect assumptions.

    A pixel is not defined by how many subpixels it contains. A pixel is the smallest addressable element on a display. The number of subpixels is irrelevant to the definition of a pixel.

    Given that, counting the number of subpixels per square inch is not a valid comparison. For a given number of pixels, LCD will generally look sharper than OLED, with inferior color reproduction and reduced antialiasing performance.
     
  17. ultravegeta1981 macrumors 6502

    ultravegeta1981

    Joined:
    Oct 12, 2017
    Location:
    Turkey
    #17
    LCD looks sharper than OLED for me. The pentile displays do look less sharp. That's why I love iPhone LCDs ,best in the game.
     
  18. manhattanmania macrumors regular

    Joined:
    Jul 9, 2007
    #18
    This isn't right... you're comparing subpixels to pixels. See the below from paintcode, good breakdown:

    https://www.paintcodeapp.com/news/ultimate-guide-to-iphone-resolutions
     
  19. heov macrumors regular

    Joined:
    Aug 16, 2002
    #19
    Just adding that it is possible to adjust subpixels in many instances. MS does it with clear type all the way back in 2000... https://docs.microsoft.com/en-us/typography/cleartype/
     
  20. techconc macrumors member

    Joined:
    Aug 16, 2011
    #20
    For Pentile based screens, it's actually worse than what you describe. The iPhone XS Max is actually equivalent to 324 ppi of a standard RGB based screen. For the red and blue pixels, you take the stated pixel density / sqrt(2). Technically the green sub pixels are 458 ppi as stated. However, since images aren't completely green in the exact shade of the green sub pixel, you need a full complement of colors for each pixel.
     
  21. EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #21
    Well, to my eye, the OLED screens of the iPhone XS/Max have clearer text than the iPhone XR.
     
  22. techconc macrumors member

    Joined:
    Aug 16, 2011
    #22
    You're missing the point. There is a difference in the quality of pixels. When comparing Pentile to RGB based arrangements, it's not an Apple to Apples comparison. In order to achieve the same quality, Pentile based displays need higher pixel density than RGB based displays. Pentile based displays are effectively "cheating" by not having complete sub pixels.
    --- Post Merged, Nov 19, 2018 ---
    I certainly can't argue about what difference you are able to perceive. I cannot discern such a difference. Maybe your eyes are better than mine? I would also note that there is likely a difference in anti-aliasing that's used for both screens due to the inherent differences of screen type. To that end, I would also ask if you think you're able to see a difference in color photographs, etc.
     
  23. EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #23
    For photographs I see no difference in fine detail, but I'm not really looking for that anyway. My main concern here is text quality.

    I bought a XR for my wife and have been comparing it to my 7 Plus, and I'm sticking with the 7 Plus, because small text on certain sites (esp. with certain fonts) is noticeably clearer.

    Note that I wear progressive lenses for my glasses, so I effectively have reading glasses on at all times to compensate for my presbyopia. In fact, if anything, the difference may be magnified soon, since my new prescription increases my near focus boost for reading to +1.5 diopters (vs the 1.0 diopters in my old prescription).

    1523023.jpg

    maxresdefault.jpg
     
  24. Gudi macrumors 68030

    Gudi

    Joined:
    May 3, 2013
    Location:
    Berlin, Berlin
    #24
    Because it was a big deal. At a typical viewing distance the difference between Non-Retina and Retina is very noticeable, whereas the difference between Super-Retina and Retina is hardly visible. Steve Jobs explained it on stage, there’s a limit to what the human eye can see and we’ve surpassed it. The numbers beyond 300ppi mean nothing anymore.
     
  25. EugW, Nov 19, 2018
    Last edited: Nov 19, 2018

    EugW thread starter macrumors 603

    EugW

    Joined:
    Jun 18, 2017
    #25
    That is not correct. Someone with near perfect human vision can discern up to about 475 ppi (in LCD terms) at normal viewing distances. That is rare though. OTOH, it's pretty common for people to be able discern more detail beyond 326 ppi.

    326 ppi is good enough for most, but there is still a significant minority of the population that can appreciate pixel densities higher than that. This includes those with 20 year-old eyes, and others with properly corrected vision - eyeglass wearers, myself included.

    If you had said "The numbers beyond 400 ppi mean nothing", I might have agreed with you. But for 300 ppi, that is not enough.
     

Share This Page

35 September 18, 2018