Images
Trilium supports storing and displaying images. Supported formats are JPEG, PNG and GIF.
Image is actually type of note placed into the note tree. It's reference can be copied into text note, so it is displayed in the text itself.
To add image to the note, simply drag it from file explorer onto the note editor inside Trilium and image will be uploaded.
Alternatively you can click on block toolbar and then on "Insert image":
You can also copy and paste image from web - the image will be (asynchronously) downloaded and embedded.
Since Trilium isn't really meant to be primary storage for image data, it attempts to compress and resize (with pretty aggressive settings) uploaded images before storing them to the database. You may then notice some quality degradation. Basic quality settings is available in Options -> Other.
If you want to save images in their original resolution, it is recommended to save them as attachment to note (top-right "Note actions -> Upload file").