It is possible to have an image in a report that is sourced from a URL rather than being retrieved directly from a datasource, here are the steps to accomplish this:
1) create a Calculated Field that contains the HTML img src tag
2) at this stage that will give you a report that just shows the URL
3) next you have to change the column format from text to HTML Formatter
4) don't forget to set the option Remove HTML tags to No
5) now the image will appear in the report
(N.B. to add an image directly from a database please follow this link)