Skip navigation

FYI- IBA 1.1 image resampling to account for retina display

1677 Views 20 Replies Latest reply: Mar 11, 2012 10:52 AM by foxbetti RSS
1 2 Previous Next
Barnheisel Level 2 Level 2 (240 points)
Currently Being Moderated
Mar 8, 2012 6:02 PM

To make the ibooks ipad 3 ready IBA 1.1 now down samples images to 264 ppi(instead of 132ppi)


Because the display in IBA is based on 132ppi the measurements you see in the inspector are half what the resampled image will be.


IBA will down sample to double what the measurement is in the inspector

and anything larger then 1024pt in the inspector (2048 actual size)will be down sampled to 2048


example: if you place an image that is 3000pix square on a page and use at original size

IBA will re-sample to 2048px x 2048px


if you scale that image so it says 1500pt x 1500pt in the inspector

IBA wil resample to 2048px x 2048px


Anything scaled to less the 1024pt in the inspector will be resampled by IBA at twice that.


So if you scale that image to 900pt x 900pt in the inspector

IBA will resample it to 1800px x 1800px


if your original image is less then twice the inspector measurements IBA does not resample.


ie original image is 600pix x 600pix and you scale it to 400pt x 400pt in the inspector, it will not be resampled.


also note IBA 1.1 now converts non transparent PGNs to JPGs



  • K T Level 7 Level 7 (23,215 points)

    Good info, thanks - but there is no 'iPad 3' - simply the 'new iPad', according to Apple.

  • Fabe Level 3 Level 3 (620 points)

    My question Barns is this: How should the inspector HxW number be read? Thanks. - Fabe

  • Fabe Level 3 Level 3 (620 points)

    Okay, I understand. Thanks.  - Fabe

  • Fabe Level 3 Level 3 (620 points)

    When we get our hands on a new High-Res iPad, what do you think would be a good simple test to describe what you are talking about? (This could be a tip!)  - Fabe

  • heySkippy Level 1 Level 1 (45 points)

    Something else to keep in mind is the file size. I updated to IBA 1.1 this morning and resaved my book and the output iBooks file size jumped from 75 MB up to 115 MB. This is a book file with about 225 pictures from a 6 MP camera.


    Not a killer for me, but it might be important to someone with a book that's closer to to the maximum file size limit.

  • Fabe Level 3 Level 3 (620 points)

    A test & question:



    RAW photo converted to jpg and set to look its best in the iPad3.

    Are these the optimal settings?


    iBA placed.png

    Photo placed on a page in iBooks Author. Note size reflects the image size on page, not the actual image size.


    iBA Original.png

    Image displayed at full size when "Original Size" is clicked.

    Note the Size dimensions reflect the full image as displayed.


    File Sizes.png

    The difference in file size between original RAW and jpg images.

    - - - -


    My question is open ended. What is the best file size to take advantage of the new iPad's resolution and what is the best workflow to create it? - Fabe

  • Fabe Level 3 Level 3 (620 points)

    your image original pixel size should be twice what it is displayed in the inspector(after you scale it to your liking).


    anything higher IBA will down sample it to twice the size.

    not a problem, but it doesn't make a difference to have it be larger.





    My test were all based on looking at the files after exporting as a ibook.

    (unzip .ibook file and look at assets)


    Barns, I followed your lead and took a look at the photograph in an unzipped .ibooks file.


    Screen Shot 2012-03-09 at 11.01.35 AM.png

    Sure enough it's been reduced from 1.4 MB to 229 KB. There is an additional rendition called "flow-1.png" weighing in at 125 KB.


    What I am taking away from what youare saying is this: whatever the size of your photo in iBooks Author,, it only needs to be twice its size to render correctly in the new hi-res iPads. Is that correct? Thanks.  - Fabe

  • Fabe Level 3 Level 3 (620 points)

    I unzipped my .ibooks file and looked inside. Sure enough the 1.4 MB photo is now 229 KB in size. So I am understanding more, but I am still trying to understand what the best workflow will be when it comes to dealing with photos post processed in Photoshop.  - Fabe

  • MrBlobby1970 Level 1 Level 1 (25 points)

    I'm confused by this. Because though I have to size an image for the layout page, what happens when the user taps on it and isolates it in full image view? I didn't think it resized based on the dimensions of the layout version.


    In other words, what you're saying is, even if I save an image at 2048 x 1536 (to take advantage of the new retina display), if I then plop that image in a layout and resize it to whatever size, when a user taps on the image to show it in full isolated image view, it won't keep that 2048x1536 resolution -- instead, IBA will simply double whatever the dimensions I set for the image when I placed it in the layout view?

1 2 Previous Next


More Like This

  • Retrieving data ...

Bookmarked By (2)

This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.