Compressing/reducing file size for Kindles

Posted on 2013-09-28
Medium Priority
Last Modified: 2013-12-11
I have listed a handful of kindle ebooks on Amazon. Since the ebooks were already completed and being sold in PDF form from my website, I used a sub-contractor to convert them all.

Amazon has a 50MB file limit/ebook prior to being uploaded. All of my ebooks contain many photographs and are therefore each between 30-42MB in size. From my WEBSITE, my best seller from the series of 5 was a consolidation which essentially is a collection of all 5 individual ebooks. The price for the "collection" was about the cost of 3.5 individual ebooks, if bought separately.

How can I duplicate the collection for Amazon when the file size would be greater than Amazon's 50MB maximum? Is there any way to "compress" mobi format ebooks and combine several of them? Or, any other approach, other than reducing the size or resolution of the images before conversion, because they are already slightly smaller than I wanted?

Question by:photoman11
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Accepted Solution

BillDL earned 2000 total points
ID: 39530871
Hi photoman

Your business, as is aparent from your user name and from previous questions of yours that I have particpated in, is photography tuition.  I can understand why you would need images of good resolution nto be of any value, however ....

You mentioned "reducing size or resolution ....... they are already slightly smaller than I wanted".

Did you reduce the pixel dimensions to make the file sizes smaller, or was this just a limitation and requirement of the eBook format?

Do you have the original images that were used to create the PDF eBooks?

What format are they, JPG, PNG, other?

It is possible to create your own Kindle MOBI format either through Kindle Direct Publishing (where you can upload properly formatted documents in a number of different formats for conversion), OR by a conversion process using some freely available software, eg. MS Word, Text Editor, Sigil, Calibre, and probably a number more since I took notes about this back in 2012.  If creating your own on your computer you can view them immediately on your computer using the appropriate Kindle Reader.

I assume that you have already experimented by saving the images at varying levels of compression rather than resizing them physically?  There is always a compression level where the image becomes unacceptable for intended use, and you can then back off a bit and produce images that are significantly smaller in file size but almost indistinguishable from the uncompressed ones, or those with lesser compression.  Of course, that is while being viewed normally.  When zooming in to see detail, as may be the intention with your publications, the greater compression would be apparent.

Another way that you can reduce the file size of images without affecting the quality, is to remove all the metadata (primarily EXIF data, but others too).  Digital cameras and image editing software write tons of data into images that is probably not required or even useful in an eBook and to Kindle Readers.

There are utilities to remove metadata, such as Jstrip for JPG images by David Crowell.  There are probably others for PNG images and other image formats.

The actual code that is used to supply the formatting of the eBooks can probably be compressed to remove superfluous white space and new lines.  Normally people writing their own eBooks using something like MS Word save the first pass as "filtered HTML" to remove extraneous microsoftish code from their basic web format document.  The conversion then takes all the HTML tags used for the layout and converts them into XML formatting.  XML is normally one line to a tag, but should also work by removing the new line characters and condensing it all, in a similar way to how JavaScript JS files are compressed/condensed to make the files smaller.    Perhaps this is done at conversion time, but it is worth looking at to see if this is an area you could cut down file size.

I hope this helps a bit.


Author Comment

ID: 39533792

WOW - what an encyclopedic response. It's going to take me awhile to go through it and try things and understand it. Just wanted to let you know how much I appreciated your answer and it may be a few days before I can get back to you with an intelligent response.

LVL 39

Expert Comment

ID: 39537158
Hi photoman.

There's no rush.  It's a fair amount to digest, especially if you decided to try and create your own eBooks using Kindle Direct Publishing and start exploring the formatting requirements of their online conversion to final Kindle publication.

The problem (as with so many IT technologies in this day and age) is that whenever some clever and enterprising people come up with programs that allow you to write and edit your own content and then convert into a format usable by certain devices or software, within a short time the technology has advanced and it becomes quite hard for those program writers to keep up with the changes.  The programs I mentioned (Sigil and Calibre) were originally created to produce content for eBook Readers that have now packed in a lot more features (eg. Kindle --> Kindle Fire), and there is the possibility that there could be the odd glitch here and there with creating publications that are compatible with the most recent reading devices.

It IS handy, however, that Microsoft Word can create formatting that can be uploaded directly to Kindle Direct Publishing as long as it is saved out as an "HTML Filtered" web page (htm/html file).   That makes things very accessible to the vast majority of people with Windows PCs, and without having to learn a whole bunch of programming skills.

As I said, there's no rush in posting back.
LVL 39

Expert Comment

ID: 39713226
Tjank you photoman

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