How to Save Memory on Repeated Pictures in a Kindle eBook

Border Thin JPEG

Border Thin JPEG

Border Thin JPEG

There are a few advantages of minimizing the file size of an eBook:

  • The minimum Kindle price depends on the converted .mobi file size (available on the second page of publishing with Kindle Direct Publishing). The list price can only be 99 cents to $1.98 if the file size is under 3 MB and between $1.99 and $2.98 if the file size is between 3 MB and 10 MB. Authors intending to price their books under $2.99 (for which the royalty will be 35%) need to be aware of these limits.
  • Each eBook publisher has a maximum file size. For example, Amazon’s Kindle is 50 MB, Sony’s Reader is 5 MB. If a file is a little above these limits, reducing the file size allows it to be published as a single volume.
  • The eBook takes up room on the customer’s device. Some customers may be reluctant to buy eBooks with larger file sizes. Large files also take longer to download, especially on older devices. Depending upon the formatting, they might also be more susceptible to file problems.

Books with images tend to have larger file sizes. Compressing the images is the simplest way to reduce file size.

For Kindle, gray lines tend to show on one or more edges of the pictures when using Microsoft Word unless the file is saved as web page, filtered. After doing this, find the file in the saved folder, right-click the file, choose Send To, and select Compressed (Zipped) Folder. Then find the folder of picture files with the same filename and copy/paste it into the zipped folder. Upload this zipped folder to KDP. This should remove those gray lines.

(When using Word, insert the picture using Insert > Picture and select the file. Then right-click the picture, choose Size, and change Width to 100%. If the picture doesn’t fit on the screen, don’t worry – it will fit on the device, which you can check in the preview. Place each picture on its own line and wrapped In Line With Text.)

If pictures are repeated in a Microsoft Word file, this wastes memory. Suppose, for example, a book features a decorative page border. A one-a-day book (of quotations, for example) might stand out by featuring a visually appealing wide, short border. But even if the picture size is small, with 365 such images, the overall file size may be significant. As another example, consider a book of shuffled flashcards, where there are several copies of each picture.

There is a simple way to avoid adding to the overall file size when pictures are repeated:

  • First, don’t copy/paste the image in Word. Just insert each different picture once. Where you want to insert a copy of a picture, put a short note, like PIC14. Then later on you can use find and replace.
  • Next, open the filtered webpage (described in a previous paragraph) before making the compressed (zipped) folder in Notepad. Don’t edit this file in Word because Word will probably mess up the HTML.
  • Don’t worry, you don’t need to know any HTML or programming.
  • Find the actual pictures in the HTML file. The code will look something like this:

<h1><img border=0 width=1116 height=153 src=”filename_files/image005.jpg”></h1>

  • The actual code may look different. It may have <p> tags instead of <h1> tags and it may have other statements not shown here.
  • If there is a statement like id=”Picture 19″, remove it. This is superfluous. But if you copy/paste the picture code with the id number, then the same id number will be used twice. Avoid this problem by removing it.
  • Copy the code for your picture, from <h1> to </h1> (or <p> to </p>).
  • Use find and replace to change things like PIC14 (which you should have placed on its own line) to the code for the actual picture. You should have something like <h1>PIC14</h1> (or with <p>’s).
  • Repeat this process for any other pictures that are repeated.
  • Preview your eBook carefully before you publish. If you make any mistakes, this is your opportunity to catch them before your customers do. 🙂

Chris McMullen, self-published author of A Detailed Guide to Self-Publishing with Amazon and Other Online Booksellers

A Picture’s Worth Ten or a Hundred Thousand Words

According to the age-old adage, “A picture’s worth a thousand words.” That may be true in terms of how much writing it would take to describe what is shown in a picture.

Bear Words

However, when it comes to file size, this equation doesn’t hold true. Instead, a single picture may equate to tens or hundreds of thousands of words.

Each letter in a word uses one byte of memory. A small, simple JPEG picture that measures about 200 pixels by 200 pixels might have a file size of about 10 to 20 kb, where each kilobyte (kb) is 1000 bytes. A simple JPEG picture that measures 1200 x 1600 pixels might have a file size of hundreds of kb. Higher resolution images or rich formatting may easily drive the file size into megabytes, where each megabyte (Mb) equals 1000 kb or 1,000,000 bytes. (Note: k = kilo = thousand, M = mega = million. You wouldn’t mind earning a M$ from your royalties, for example.)

If a word is about 5 letters long, on average, this means that a simple 200 x 200 JPEG picture takes as much memory as about a few thousand words, a 1200 x 1600 JPEG picture equates to about a hundred thousand words, and higher-resolution or richly formatted pictures are worth nearly a million words.

Why does this matter? This affects both publishers (including self-published authors) and readers of eBooks. First, there is a maximum size on the content file of an eBook – for Kindle, it is 50 Mb, and for Nook, it is 20 Mb. An eBook that features many large, high-resolution, richly formatted pictures is in danger of exceeding this limit.

Secondly, the content file size may affect the list price and royalty. For example, with Amazon’s Kindle, an eBook can only have a list price of 99 cents if the content file size is below 3 Mb and a list price of $1.99 if the content file size is below 10 Mb; otherwise, the minimum list price is $2.99. If you want to sell a Kindle eBook for less than $2.99, you must keep the file size below these thresholds.

Also, Amazon deducts 15 cents per Mb from the list price before applying the royalty percentage for Kindle eBooks on the 70% royalty option. For example, suppose that you have a 10 Mb eBook that you want to sell for $4.99 on the Kindle. The file size deduction is $0.15 x 10 = $1.50, which means that the royalty is ($4.99 – $1.50) x 0.70 = $3.49 x 0.70 = $2.44. If the file size could be reduced to 5 Mb, the royalty would be increased to $2.97. In this example, saving 5 Mb of file size adds 50 cents to the royalty. For every 1000 books sold, this amounts to $500.

The effect of pictures on file size affects both customers and publishers. Customers appreciate pictures, especially if they have a color eReader like the Kindle Fire or Nook Color. They also like the pictures to have high enough resolution to see the image clearly on any device (from a tiny iPhone to an iPad) and to be formatted well. However, including more pictures also affects the price of the eBook, and – another important consideration – the delivery time of the download (the delay is even longer for older eReaders).

There is a trade-off between the benefits of including many high-resolution pictures and the disadvantages this has in terms of list price eligibility, royalty, and delivery time. The publisher is faced with a difficult challenge to balance this properly.

However, there are a few ways to decrease the size of the content file for the eBook. Keep in mind that you don’t want to sacrifice image quality in the content file for a paperback book, so you need to have two separate content files for your book – one for the eBook and another for the paperback.

In Microsoft Word, right-click on any picture in your content file, choose the Format tab at the bottom of the page, select Format Pictures, uncheck the Apply Only To This Picture box, and select a Target Output (if you have an older edition of Word, like 2003, the instructions are a bit different). E-mail resolution (96 ppi – pixels per inch) will give you the minimum possible file size, and is generally suitable for eReaders. I suggest saving your file with different names before and after trying this so that you still have the original.

Paperback books have the opposite problem. If you submit content and cover files to CreateSpace, for example, a common error is that a picture has a DPI (dots per inch) of less than 200. You want high resolution images on your paperback book, where there is a generous maximum content file size of 400 Mb.

Note the distinction between resolution and DPI. The resolution of a picture is based on how many pixels it measures across and high (like 600 x 800, which is common for full-screen images on eReaders), whereas DPI measures how many dots there are per inch on the printed page. The size of the picture in addition to the resolution affect how many pixels will span one inch.

Coincidentally, there are about 930 words in this blog article. So this blog is equivalent to a single picture – or about a tenth or hundredth of one in modern terms. Picture that!

Chris McMullen, self-published author of A Detailed Guide to Self-Publishing with Amazon and Other Online Booksellers (Volume 2 coming in mid-April)

Fighting Word’s Picture Compression

Microsoft Word has a tendency to compress pictures down to as little as 96 dots per inch (DPI), even when the box is checked telling Word not to do this. That’s great when there is a priority on saving memory, but not desirable when printing for quality.

The first step is to disable automatic picture compression, while realizing that this step – all by itself – is not sufficient. In Word 2010, for example, click the File tab, scroll down below Help to find Options (at first hidden toward the bottom of the list), select Advanced, scroll down to Image Size and Quality, and check the box that says, “Do not compress images in file.” Do this before inserting any images into the file.

Don’t copy and paste pictures into the Word document. Instead, click Insert and then Picture.

Don’t resize or otherwise manipulate the pictures in Word. Instead, edit the images with photo-editing software that doesn’t compress them prior to inserting them into the Word document.

Don’t use Save As to convert the Word document to PDF. Instead, print the file to PDF using a Word-to-PDF converter. For self-publishing, find a PDF converter that allows fonts to be embedded in the file and transparency to be flattened.

Also, check the DPI of the pictures at the source – i.e. the software (e.g. PhotoShop) or device (e.g. camera or scanner) that created the pictures. Using 300 DPI or more produces sufficient print quality images for most applications.


As long as we’re talking about pictures, I may as well include one with a tesseract and a half-dozen planes intersecting in four-dimensional space. If anything else, it may help to make Word’s picture compression seem somewhat less complicated. 🙂

Authors of eBooks have the opposite problem. With eBooks, what counts is the number of pixels along the width and height. In this case, there is a premium on compressing the images in order to minimize the file size of the eBook. To compress the pictures in Word 2010, right-click a picture, go to the Format tab (that appears when a picture is selected), click Compress Pictures, choose 96 DPI (KDP’s recommendation for most eBooks), and uncheck the box that says, “Only to this picture.”

For eBooks, after inserting an image into Word, right-click the image, choose Size and Position, go to the Size tab (in the pop-up window), and set both the width and height to 100% scaling (Word automatically scales images down to a lower percentage when they would otherwise exceed the margin width).

May your pictures come out picture-perfect! 🙂

Copyright (c) Chris McMullen, Author of the Improve Your Math Fluency series of workbooks and self-publishing guides