Each picture that appears in an Open XML Format document is stored in the ZIP package as an image file. Regardless of how many times the picture appears in the document, only one copy of the image file is required in the ZIP package.
Images are stored in an Open XML Format ZIP package as individual picture files (such as .jpg and .png files). So, every picture that you see in a document — whether it is in the body of document, in a header or footer, or even used as a background — is accessible as a separate file stored in the ZIP package.
Image files are located in the main document folder (such as the word folder or the ppt folder), inside a subfolder named media, and are named image#.
Additionally, the following references are included in the ZIP package:
- Wherever the image appears in a document, an XML reference to the picture file appears in the applicable document part.
- A default extension definition is included in [Content_Types].xml for each file format included in the document (such as .jpg or .png in the case of image files).
- A relationship is added to the appropriate .rels file for each document part where the image appears, such as document.xml.rels.