Hi,
While uploading an EPUB file to Apple Books, I encountered an error message below.
I should reduce the dimension of the file.
But I can't fine out 1165.png.
It is not in the LINKS panel.
Would you help me find out the location of 1165.png?
Housn Kang
6 Correct answers
I can see from your Links panel you have some image files that are full page. When you export to EPUB the image resolution you choose is likely exceeding Apple’s 4,000,000 pixel size limit. For example if your page size is 8"x10", choosing 300ppi would exceed the limit 2400 x 3000=7,200,000. Try setting your conversion Settings>Resolution to 150ppi or less.
It’s the pixel dimensions of an 8”x10” page output at 300ppi—(8x300)x(10x300)=7,200,000.
An 8.5 x 11 page would be 2550x3300. Apple is limiting the total number of pixels in an image to 4,000,000, so you multiply the width x height to get total pixels.
Unfortunately you have to choose from the 4 preset output resolutions with an epub export. If 200ppi were an option 8.5"x11" would be under the Apple 4,000,000 pixel limit.
You could reduce your page dimension and get a larger pixel dimension under the Apple limit using 300ppi. So if the page is 5.66" x 7.33" the output pixel dimensions at 300ppi would be 1700x2200—3,740,000
The epub is going to be responsive to the device it is read on, so the print output dimensions as inches has no meaning. The larger pixel dimensions would be sampled to fit the device. So on a large, high res device like an iPad Pro the extra resolution might have a benefit, but on a small iPhone the pixel dimensions would be sampled down to fit the device.
In the case of the iPhone both a 300ppi and 150ppi spread would have to be sampled down to fit the smaller physical screen size. At a 150ppi, the image spread would have a pixel dimension of 2550 x 1650 and would be reduced by 75% in order to fit the phone's 1242 short side pixel dimension (1920x1242). The phone’s effective resolution is 458ppi compared to the MacBook’s 227ppi so the text will be crisper because of the considerably higher effective resolution.
The 2550 x 1650 spread will also
...
Your 2550x1650 pixel spread will have to be scaled or resampled up to fit in the 11.989" X 7.758" iPad Pro screen, so the effective resolution of your 2550x1650 image would be 212ppi. In the case of the iPad Pro there would be some improvement by working at a smaller page size and exporting at 300ppi to stay under Apple‘s limit, but not much.
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Replies
Now, I can better undestand the innerwokings of Id.
1.
When I publish a book on Apple Books next time, I think, "Avoding a full-page image file is the best way to get around un unexpected error."
2.
Based on your reply, I should reduce the page size, if I want to keep 300ppi (image below).
Can you figure out if there is any difference between 1 and 2, when they are presented by the Books app on Mac or iPhone? Hard to imagine the effect of smaller page size, higher resolution, larger page dimension.
Hosun Kang
Your remarks remind me of one more thing I observed.
From the beginning, my EPUB was presented differently on Mac and iPhone.
On Mac, color looks a little desuturated and font becomes less crisp with the EPUB at 150ppi and 300ppi.
Does the difference come from the dispaly specifications or EPUB?
Hosun Kang
(Currently, I don't have iPad.)
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