simple-scan is missing a high contrast icon. Please add a high contrast icon to simple-scan.
Simple Scan uses the "scanner" icon in its desktop file, which is part of the freedesktop.org icon naming specification, and which is present in the HighContrast icon theme. As it does not provide its own icon, I suppose that it should also not provide its own high contrast icon?
The scanner icon in the high contrast theme is a red circle. This is not an appropriate High Contrast icon. If you think I should file it upstream (wherever the red circle icon comes from) than I would do it.
This icon is not part of Simple Scan, but I think that it comes from gnome-themes-standard.
I'll file a bug there.