I would know how to import a background image on iReport designer 4.1.2.
These are the step I take:
The background image appears properly in the report but when launch the preview it disappears!
What's wrong? I miss something?
PS: I discarded the Background band solution because the image exceed the report margins.
Sorry, I didn't read the question carefully at first. You need to use the background band. Resize your image to be the appropriate size so you can use it. After doing that...
Export to PDF and you should see the background image. Export to XHTML and you should see the background image.
When you export to HTML background images won't display. The FAQ link on the JasperReports page explains things (like this!) that you need to consider in HTML reports.
The background image does not do what you want. It is intended to provide a background while you are editing the report in iReport. It has no effect on the final report.