I needed to extract two diagrams from a worksheet in a Microsoft Excel workbook. The diagrams appeared to have been put in the worksheet as an image through a copy and paste operation. I could right-click on an image in the sheet and choose "Copy" or "Save as Picture" and for the latter option I could choose PNG, JPEG, PDF, GIF, or BMP for the "Save as Type" value, but I wondered what type of file Excel was using for the embedded image. The file was a .xlsm file, which like a .xlsx file is an Office Open XML (OpenXML) file format that can be "unzipped" to reveal the constituent files within it by renaming the file to have a .zip filename extension or copying the file to a new file with a .zip extension - see Zipping and unzipping Excel xlsx files. So I copied the file giving the new file a .zip extension and then extracted the contents of that file by unzipping it. I then had a file named "[Content_Types].xml" and the following directories in the directory where I had extracted files from the zip file:
_rels
customXml
docProps
xl
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