Why do some images get larger size after exporting to ibook?

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Why do some images get larger size after exporting to ibook?

Hi Guys:

I put some images in a Gallery widget, each of them are around 800kb, 2048 * 1496

then I export the book as an mybook.ibook, rename it to mybook.zip and unzip so as to inspect the file size of the image.

To my surprise, the image is 1.5MB in the ibook folder.

What makes the image grow from 800kb up to 1.5MB?

Each imange is cropped and compressed from a 7MB photo. Is iBookAuthor trying to restore the image to pursue a good quality?

If this is the case, unfortuately, the total size of the book won't be under my control.

Any hint & suggestion will be appreicated.

Thanks a lot.

Xing Yun

MacBook Pro with Retina display, OS X Mavericks (10.9.2), iBookAuthor 2.1.1(459)

Posted on Apr 8, 2014 6:31 AM

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Answer 1

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vinnyvg

Level 4

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Apr 8, 2014 5:34 PM in response to BigFatDog

No need to go to the trouble of changing suffix to .zip and getting into the raw files.

Use the Inspector, go to the 'Rule" icon sixth from the left and it shows the screen size of your images and an option to view the "original" size.

If you want more information of images - open your iTunesConnect > Deliver your Content and on top right are some PDFs one of which is the Asset Guide which should explain your image size changes.

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Answer 2

BigFatDog Author

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Apr 8, 2014 10:44 PM in response to vinnyvg

Thank you for your kindly help, I'll try that.

My conclusion is to use image in higher quality, and leave it for iBookAuthor to compress them.

If the total size of the book becomes a problem, then remove some images and keep the best of them.

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Answer 3

vinnyvg

Level 4

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Apr 9, 2014 3:04 PM in response to BigFatDog

Beware making your images too big. You should check the Help files ...Media and Graphics and its better t o download the Asset guide.

Max image size is 3.2million px or 2048 x 1536 @ 72PPI/DPI - comply with this and ignore what Apple does with the "engine".

Max book size is 2 gigabyte

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Answer 4

BigFatDog Author

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Apr 9, 2014 6:47 PM in response to vinnyvg

Sure, I'll keep this in mind.

However, I don't agree with you on the proper resolution:

I make image 2048 x 1496, above 264ppi (3rd or 4th ipad's ppi), usually 300-350ppi

The image will cover exactly the fullscreen with the given settings in the "Inspector"

Size: 1024, 748

Position: 0, 0

Currently, this approach works well for both fullscreen non-interactive images and gallery widgets.

Making the image 2048 x 1536 will exceed the page.

Am I making anything wrong?

Thank you.

Xing Yun

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Answer 5

vinnyvg

Level 4

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Apr 10, 2014 12:17 AM in response to BigFatDog

Making the image 2048 x 1536 will exceed the page.

Sorry, the size I gave is the screenshot size and iPad screen size - which equals the 3.2million max image size allowed.

I use my images this size because in my Photo books.. I do not use images full ( iBA) page size.

You may find when running a preview on iPad that the iBA page size with a full size image - that the tap to magnify to screen size does not work.

Photographers want images with high resolution to make a sharp, crisp image, the Retina screeen resolution is 264, so processing to 300-350ppi is not needed and makes no difference.

Previoulsy when I suggested to others to use a resolution of 264 - I was constantly being scolded by a long serving group memember who insisted that resolution above 72pp not needed and simply "bloated" the image.

My opinion was that if I matched the screen resolution of 264 for Retina screen - it was optomised for the screens capabilities.

The asset guide states:-

Optimizing Images in Fixed Layout Books

In addition to the image recommendations in “Interior Image Requirements” (page 24), the following apply

to working with images in Fixed Layout books:

● Images inside Fixed Layout books must be in JPEG or PNG format. To reduce file size, use JPEG for any

images that do not require transparency. Using JPEGs results in a smaller file size and better performance.

We recommend using a quality of 85 for JPEGs.

● Images inside Fixed Layout books must not exceed 3.2 million pixels. You can calculate whether an image

inside the book file exceeds 3.2 million pixels by multiplying the height and width of the image

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Answer 6

BigFatDog Author

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Apr 10, 2014 12:47 AM in response to vinnyvg

Finally... thank you for your patience and help!

There shall be 2 resolutions in total, I'd go back to re-work on my book.

There are 140 pages and it may take me several days to refine all those images.

Your answer resolves my problem.

Here're something I got from google:

In iBooks Author there are several ways of displaying images utilizing the full screen:

Static Full Page Image – Images can be displayed at full screen on a given page in iBooks. Since the interface reserves 20 pixels at the top for a status bar, the image should be sized at 1024×748.
Borderless Images – By placing images in a gallery widget you can display images at full screen in response to a touch. When the image is expanded the status bar disappears and the image can be as large as 1024×768.

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Answer 7

vinnyvg

Level 4

1,880 points

Apr 10, 2014 4:05 PM in response to BigFatDog

1024×768. x 2 = 2048 x 1536, the size I prefer to use!

For Retina screens its advisable to use 2048 x 1536 resolution can be 72 - 264ppi but remember max images size is 3.2million gigabyte ( 2048 x1536 = 3.145,728 gb)

I use either Photoshop CC or Photoshop Elements 12 to batch process all images I set aside for a particular book.

( For those who do not have these or other image editors, the iMacs "Preview" can adjust individual images. )

A tip to please Apple, even though you may be using lots of images, you should give a thought to adding at least one Photo gallery, even if it has just 4 images and it can fit on a mainly text page at - say quarter the screen size.

Also if you can, use iMovie or similar, to create an into movie - simply by using a few images - which are alrerady on your pages... its acceptable because its an "introduction to the content".

Apple / Review team like to see our books using most if not all the widgets on pages and although they do not get you through the review any faster, they can makes your books look more "professional".

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Answer 8

BigFatDog Author

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Apr 10, 2014 7:58 PM in response to vinnyvg

I'm changing the images that are shown in gallery from 2048*1496 to 2048*1536, 264ppi, and leaving the static fullscreen ones 2048 * 1496

I save the image to JPEG in quality 10, via the Photoshop CC.

I prefer to the gallery, too.

I'd like to use gallery even if there's only one image to be shown, due to the fact that: "iBooks Author to display photos on a WHITE background when an image is displayed full-screen"

One of the disadvantages of gallery widget is it cannot be decorated with a "Picture frame or line storke" in non-fullscreen mode.

I sometimes add another 100% transparent shape with "Picture frame stroke" overlay on a gallery.

It looks better, although it will defintely lose the picture frame when going to fullscreen.

Sure. "Introduction to the content" will make the book appear more professional. I'll defintely do this.

However, it shall be a proper time to add this when the entire book is nearly finished.

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Answer 9

Feb 27, 2015 9:42 AM in response to BigFatDog

The image "resolution" is not applicable to screen display.

The only parameters that affect how your images are displayed on a screen are the image size (pixel dimensions), the device on which the image is displayed, and if present, the specified image "width" (if you use html).

A 300 x 300 px image WOULD will be - without further alteration - rendered at 1/2 the size on a device with a native resolution of 250 ppi as it would on a device with a native resolution of 125 ppi

If you use Ibooks Author, Apple displays them both at the same size in Ibooks when view on retinal or non-retinal screens because it "knows" (via operating system / authoring software) what the intended display size is - but the sharpness will be less in the lower resolution device.

Ignore "resolution" - that only has meaning for print applications.

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