You can print images directly without converting them to PDF first.
You can usually do it by right-clicking the image and choosing Print, although you may find an unwanted program has taken over the action for some file types. (e.g. Here, on BMP but not JPG, Photoshop has taken over the Print action for some reason, despite taking ages to load and being completely unsuitable.)
Within Opus, you could set up a button, hotkey or context menu item which runs the Opus print command (no arguments required) and that will also send any image Opus can decode straight to the standard Windows Print dialog.