Reducing file size by optimising images

One of the many problems with images and their storage in Microsoft Office documents (Word, Excel and PowerPoint), is the lack of understanding of how this data is stored and the impact that this can have on the disk space used to store the document.

As an example, we'll import the picture below into a Word document. The image is 4.13 MB in size with a resolution of 3801 x 4978 pixels.

Word will automatically resize the image to fit the margins of the document but the image data remains unaltered.

To confirm this, right-click on the image and select Picture > Size to show that Word has reduced the image to 12% of its original size.

Because of this, the saved Word document in our example is over 4.2 MB.

Compressing an image within a Word document.

Left-click the imported image and select Picture Tools > Format > Compress Pictures from the top menu.

In the Compress Pictures dialog box, select either Selected pictures or All pictures in document, then OK > Apply.

Confirm the change by right-clicking on the image and selecting Picture > Size. A height and width of 100% means the image has been successfully compressed.

With a compressed image, the saved Word document is under 400 KB.

This feature is also available in Excel and Powerpoint.