There is no way to export an image from MATLAB to Excel, unless you do some very complicated ActiveX stuff. I put thumbnail images into Excel but I wrote a Visual Basic program to do it. My MATLAB function passes the workbook filename and the image filename to the VB program. The VB program then launches Excel and reads in the workbook, reads in the image file and creates a thumbnail of it, and then finally exports the thumbnail image onto the worksheet. You see an actual image displayed in Excel.
If you want to put just THE VALUES of the image into a workbook, then you can use xlswrite. You won't get an image in the workbook but you will get pixel values (integers or some other type of number) in the Excel cells.
You might also be interested in Steve Eddins's im2html(): http://blogs.mathworks.com/steve/2012/06/02/making-an-html-table-of-pixel-values-with-colored-cells/
