NOTE: the change of text engine in Tinderbox v5.0.0 means it won't accept newly-pasted images. Images in existing documents will, in general, appear normally; some issues might arise. For additional assurance, documents that use images will open as untitled; save them with a new name while preserving a copy of the original. It is intended to re-enable previous functionality when issues with the new text engine are resolved. In the interim, consider using the File button to associate external image files with a note.
Notes with images, when exported, will export their images as JPEGs - or a non-default format asset via the Map Preference 'Link images as'. A single images is names as per the parent $HTMLExportFileName plus the appropriate format extension, e.g. "somefile.html' will export "somefile.jpg". If there is more than one image, the additional images are numbered from 1 up, e.g. "otherfile.html' will export "otherfile.jpg", "otherfile1.jpg", "otherfile2.jpg", etc. The exported images are linked by inserting an HTML 'img' tag into the exported HTML page in a position equivalent to its position in the source note's $Text.
Images in picture adornments aren't exported as adornments themselves aren't exported.
The 'Copy view picture' option in the Edit menu has also been disabled until image support is fully restored.
Given that the export process offers no control over degree of compression or where on the exported page the image is placed, it is worth considering linking exported pages to pre-made images instead - as is the case with aTbRef. If externally created images are stored/numbered as per TB's defaults, the $HTMLOverwriteImages attribute may be used to prevent TB overwriting these files with during HTML export.
See also "HTML Export - points to consider".