FreePDF: The Opacity feature is not included in FreePDF.
The opacity (i.e. transparency) can be applied to any object, even to pictures and text boxes.
To change the opacity of objects, proceed as follows:
| 1. | Select one or more objects with the Object tool  from the Quick access toolbar. |
| 2. | Choose the ribbon command Format | group Format | Opacity  . |
| 3. | In the dialog box that appears, drag the slider in order to set a value between Invisible (completely transparent) and Solid (no transparency). |
| Alternatively, enter exact values to the right of the slider. |