Changing opacity in an image

[judodan]

I'm fairly new to Jasper Reports.  I'm creating some report templates with iReport and it's working pretty well.

However, I'm having trouble putting a watermark in the background.  I've got it displaying the referenced file, but I can't figure out how to reduce the opacity.  The generated code in the JRXML file looks like this:

<background>

<band height="572" splitType="Stretch">

<image hAlign="Center" vAlign="Middle">

<reportElement uuid="5b4665ab-6e30-4260-a739-cb8c456f370a" x="179" y="97" width="400" height="400">

<printWhenExpression><![CDATA[$F{Watermark}!=null]]></printWhenExpression>

</reportElement>

<imageExpression class="java.lang.String"><![CDATA[$F{Watermark_File}]]></imageExpression>

</image>

</band>

</background>

 

Any ideas on how to do this?  Or am I going to have to read the file and transform the opacity before generating the report?  Seems like this would be something somebody has done before.

 

THanks for any help!