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Inspiring
May 24, 2019
Answered

InDesign Document Size for iPad

  • May 24, 2019
  • 3 replies
  • 5492 views

I am creating an interactive InDesign file for the iPad. I will most likely use the Publish Online feature. Since there are different sizes of iPads, what Document Size should I choose -- 1024 x 768, 2732 x 2048... or does it matter? I will be testing on a 12.9 iPad Pro. Thanks.

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    Correct answer BobLevine

    Publish Online documents will resize to fit the screen. There's virtually no point in trying to get to fit one device over another.

    3 replies

    Peter Villevoye
    Community Expert
    Community Expert
    May 25, 2019

    Creating properly sized content for the iPad can be easy, but there are some difficulties.

    The first one is an obvious one: landscape or portrait ?

    You can't lock or force the rotation of the iPad or design in a browser view. So the view will switch to what orientation the user prefers, scaling it to fit the screen's size and adding black margins to either sides. Hopefully users will understand the best orientation of your design, and rotate their iPad accordingly.

    The next one is a numbers game: output resolution.

    Depending on the setting of the physical size of your page or whole document (in pixels or inches), the export will vary the output resolution of all imagery. So if you're designing at a 4 x 3 cm size with the output set to 96 dpi (in the Advanced panel of the Publish Online dialogue), all imagery will look very sloppy ! Changing the design's size to 20 x 15 cm immediately renders more pixels into the output, giving a much better viewing experience.

    The design in InDesign, consisting of a yellow background, a simple line of text, a hi-res image with a shadow, an opaque star shape (vector), and a semi transparant pink blob (vector).

    At 96 dpi, elements in the the 4 x 3 cm document size will consequently be rendered (flattened, rasterised) into very coarse pixels. The difference between 96 and 144 dpi doesn't improve it enough. What also surprises, is that even vector-based and fully opaque elements need to be rasterised, and that overlaying bounding areas of different types of elements can yield different raster tints !

    But changing the document size to 20 x 15 cm immediately has a bigger an better impact:

    So create or scale your design to the proper physical size, or find a good average when you need to cater a wider scale of device sizes (from iPad mini to a large pro). The original iPad was quite content with 1024 x 768, but newer models range to almost three times that number of pixels.

    And last but not least: these Publish Online views are always within a browser screen, and on an iPad you can't switch to full-screen. (ePubs can be viewed full-screen, within iBooks). So you don't get the full width/height of the screen.

    rob day
    Community Expert
    Community Expert
    May 25, 2019

    Looking at the HTML that is generated by Publish Online it looks to me like the InDesign page is exported using its Inch dimensions, and any placed images are sampled to the chosen PPI Resolution relative to the page dimensions. Those images would then be responsively sized into the device's available screen dimensions.

    So, a 20cm x15cm page in inches would be  7.874" x 5.9055". If I Publish with the resolution set to 96ppi, a full bleed image exports as 756 x 567 pixels (7.874 x 96 = 755.9).

    Here's a 20cmx15cm page with a full bleed image Published at 96ppi. If I right click on the HTML's page 1 image and save it, I can confirm that its pixel dimensions are the expected 756 x 567, which would not be nearly enough resolution for optimal quality on a 2730 x 2048 iPadPro—the image is going to be sampled up nearly 4X to fit on the iPad Pro screen in landscape mode.

    https://indd.adobe.com/view/fa6b2f7e-dee3-4067-a11e-0ae833b7a17f

    If I make a 2730 x 2048 pixel InDesign page (37.9" x 28.4"), I can Publish at 72ppi and the image will export at 2730 x 2040. The page and images will now be responsively downsized on any mobile device smaller than the iPad Pro. A right click save of the image in this version saves as 2730 x 2040px

    https://indd.adobe.com/view/ec9155aa-110e-4d79-a3c3-4900b0646e17

    Peter Villevoye
    Community Expert
    Community Expert
    May 25, 2019

    You're right ! I just used the 20 x 15 cm not as a strict size to adhere to, but as an example to show how the physical size of the page/document immediately affects the output. A large iPad pro requires indeed much more pixel beef ! An old iPad mini would be content with it, if you'd subtract the browser ribbons, bars, and letter boxing...

    BobLevine
    Community Expert
    BobLevineCommunity ExpertCorrect answer
    Community Expert
    May 24, 2019

    Publish Online documents will resize to fit the screen. There's virtually no point in trying to get to fit one device over another.

    rob day
    Community Expert
    Community Expert
    May 24, 2019

    Publish Online documents will resize to fit the screen.

    Right, and for the best image quality ideally you want the resizing on any device to be a down sample and not an up sample.

    If you don't want the page images to be scaled up when they display on the 2732 x 2048 pixel iPad screen, you have to consider the relationship of the InDesign document’s page dimension and the effective resolutions of the page‘s images.

    The document size doesn't necessarily matter, but the smaller the InDesign page dimensions get the higher the Effective Resolution has to be in order for the images to be at their best when the HTML page is scaled up to fit on a higher pixel dimension screen.

    rob day
    Community Expert
    Community Expert
    May 24, 2019

    If you want to set the document up with Pixels as the measurement unit and the target is the iPad Pro, then the size should be the iPad Pro’s 2732 x 2048. In that case the listed Effective resolution of any placed images only has to be 72ppi or higher in order to get the best quality on the iPadPro.

    If you want to work in Inch units rather than Pixel units, divide the iPadPro's 2732 pixel width by the document's Inch width in order to get the optimal ipad resolution. So images placed in a 10" x 7.5" document would need a minimum Effective res of 273ppi in order to take advantage of the iPadPro’s full resolution.