How to insert images with pop up

You can do this with ease using images within comments.

When you add a comment, there will be a red triangle in the upper-right corner of the cell and every time you hover over it, the comment (image in this case) will appear.

Steps:

1. Right-click the cell and click Insert Comment.
2. Remove any default text from the comment.
3. Right-click the border of the comment and then click Format Comment...
   1. To right-click the border of the comment, you must be editing it. You can right-click the cell with the comment and click Edit Comment to get to that point.
4. Go to the Colors and Lines tab and click the drop-down menu next to where it says Color: and then click Fill Effects.
5. Go to the Picture tab, in the window that opens, and click the Select Picture... button.
6. Find the desired photo on your computer, select it, and click the Insert button.
7. Click OK and you're done.

Note: you can select the option Lock picture aspect ratio, to keep the image looking proportional when you resize the comment.