From stamp annotation configuration dialog:
- Click push button next to combo box opens a file selector
- Selecting a corrupted image file should throw an error
- Selecting a good image file shows the preview of the image
- Select a horizontal image shows a large clear preview
- Select a vertical image file shows a smaller preview without messing up the visual of the config dialog
From page view, select the stamp annotation with horizontal image file (not squared):
- Click and hold. The preview maintains proportions
- Single click. The stamp image in the pdf maintains proportions and has the same size of the click and hold preview.
- Add an annotation of the Okular custom stamps (internal SVG so treated slightly differently) do not create problems