Why is my file (size) so large?

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Why is my file (size) so large?

Post by martin »

Most often large file sizes are due to inserted graphics. Nisus Writer always preserves all original image data, even if you resize the image to display smaller on screen. So if you insert a 2MB photo, the size of your Nisus Writer file will grow to include at least 2MB of image data (and likely more).

How can I reduce the size of my file?
The best thing to do is be aware of how large your images are. If you are inserting many large images in a document, your file will grow in size accordingly. You should resize your image externally before adding it to your Nisus Writer document.

If you don't need to exchange your documents with other applications, you might also consider saving your documents using the file format Nisus Compressed Rich Text (ZRTF). This file format reduces much of the waste in RTF (see below for details on this waste). The drawback is that ZRTF is only supported by Nisus Writer.

If you need to share your documents with non-Nisus users, consider using the file format Rich Text Format Directory (RTFD). It stores all images as separate files, reducing waste. Unfortunately this format isn't widely supported. You won't be able to send your files to Windows users, and even some apps on macOS may not open your file.

How can I check if my file has large images?
The easiest way to check how much space is being used by images in your document is the menu File > Image Analysis. That will show the following summary information:
analysis.png (21.16 KiB) Viewed 3851 times

If the summary shows a lot images you can click the arrows next to the "Largest Image" labels. Each arrow button will display the related list of images sorted from largest to smallest:
list.png (25.2 KiB) Viewed 3851 times

You can then click through the list to see each image in context in your document. If there are any very large images you should resize them externally (in another app) and then re-insert them into your document.

If you're still using an older version of Nisus Writer Pro (version 2 and older), then you could use an image size check macro.

How does RTF waste disk space when saving images?
RTF wastes disk space in a variety of ways when saving images:

1. RTF does not support all image types natively. When you insert a non-native image (eg: PDF), Nisus Writer will save both the original image data, as well as an "RTF compatible" image, for the benefit of other applications. The drawback is that non-native images are essentially saved twice, which naturally increases the size of your file. To avoid this duplication, consider inserting JPG or PNG images as both formats are natively supported by RTF.

2. RTF does not by default save image data in pure binary form, but uses something called "hexadecimal escaping". While RTF does allow saving an image as binary, not all applications support this feature. To be more compatible, Nisus Writer saves image data using hexadecimal escaping. This increases the size of the image data by nearly double.

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