Quote:
Originally Posted by Peter Ahlstrom
I ran it through Kindle Previewer and saved the kpf file. Then I used jhowell's Calibre plugin KFX Import to extract the resources on the command line. And (without the embedded epub file) it's 32.4 MB. Is that an at all accurate predictor of what file size will be delivered to customers?
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For each book Amazon produces a variety of Kindle formats customized in both text formatting and image quality for different Kindle reading platforms. There is no single size that is delivered to customers.
The quality of images also depends on the type of book being published. Amazon does a better job of handling images in comics and manga than they do for reflowable format books.
When you produce a KPF file using the Kindle Previewer the images in the book are handled by a program called KindleImageProcessor. When a book is actually published Amazon uses a different program, YJImageVariantGenerator, to produce the images that will be delivered to customers. What these programs do is undocumented and has changed over time. I suspect that what you get from unpacking a KPF will be similar to the KFX variant that customers using the Kindle for iOS and Android app will receive. I know of no way to see the true images that will be delivered to customers without actually publishing.
Quote:
Originally Posted by Peter Ahlstrom
All of my carefully optimized gif files were changed to jpegs. The dimensions did not change, but the size ballooned. My biggest gif (the title page), 281 KB, became a 1.6 MB jpeg.
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Unfortunately that is the way images are handled in KFX format. They are converted to JPEG for the Kindle apps and grayscale JPEG-XR for e-ink Kindle devices. They can be downscaled in pixels and reduced in quality.
Quote:
Originally Posted by Peter Ahlstrom
I really hope this is not indicative of what the delivery size will be.
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As far as I can tell the largest file size across all of the variants produced is shown as the file size on Amazon's product page for the book. Someone who has published may be able to comment on whether the file size on the product page is the same size used to calculate delivery costs.