Using the Open XML Formats, you can easily change pictures as often as you change your mind.
Some of the tasks that will save you the most time can be even easier than editing a document part.
Images in your Open XML Format documents are stored in the ZIP package as picture files. So, to replace an image in your document, you can just replace the picture file once and Word, Excel, or PowerPoint retains placement and formatting information from the previous image. And if your image appears dozens of times throughout various parts of a document, presentation, or workbook, when you work in the XML you only have to replace that picture once.
Being able to access images so easily can be helpful for a variety of document production tasks. For example, if you need to share a picture from a document or use it in another document or program, you no longer need to copy and paste the picture and worry about loss of quality. You can simply extract and use the original picture file that resides in the ZIP package.