Learn how to reduce your ebook file size during importing PDF files

If you find your saved or exported ebook significantly larger in file size than the original PDF, then something is not right. Below you will find the most popular reasons that could have caused this.

Note your case may fall under more than one of the following reasons.

PDF Dimensions

The PDF source is already very large in dimensions. You are viewing the PDF while it's set to fit in your screen. Set the scale to 100% instead of check the real size.

How to Fix

The recommended way to fix this is to resize the PDF source before importing into Kotobee Author. This can be done using the Preflight tool in Adobe Acrobat Pro. You may also find other tools online for PDF dimension resizing.

PDF Image Format

The PDF pages were imported in an image type (i.e. PNG or GIF) that is not suitable for the content, increasing the file size.

How to Fix

In the PDF Import dialog, set the Image Type to PNG if your PDF has plenty of imagery and colored graphics, especially containing wide ranges of colors. Select GIF if your PDF has limited colors, especially if it is purely text. It may also contain graphics, but of solid colors (no gradients).

PDF Image Quality

Your PDF images may be rendered in a quality that is too high for the human eye. It may be reduced further without noticeable difference.

How to Fix

Lower the Image Quality settings in the PDF Import Dialog. You can experiment with 80% as a start.

PDF Import Mode

The PDF format renders text of special fonts as vectored objects, that don't consume large file size. When selecting the Accurate & Selectable PDF import mode, in order to have this text appearing accurately in a web (or EPUB) friendly format, the entire page is converted into a bitmap image, then overlayed with invisible text to support highlighting and text search. Converting to a bitmap image is the way to have the appearance as accurate as possible, at the cost of a larger file size.

How to Fix

This should be the last resort if none of the fixes above work. You can try avoid Accurate & Selectable PDF import mode completely, and test with the following options:

  • Try out the other modes: Editable Content and Plain Text. They will reduce the accuracy of visually matching the PDF source.
  • Use a PDF reader like Acrobat Pro, to save the PDF source as an HTML file. You can then import the HTML file into Kotobee Author.
  • Import only parts of the PDF file that require visual accuracy, using the Page range setting, and leave pages with pure text for manual insertion, or copying and pasting.