Pictures (bitmap images) can be added to Tinderbox in one of two ways:
Embedding pictures in notes
In short, this can't be done via copy/paste directly from another app. Instead, first the note must be imported into Tinderbox as a new note (as described below. Be aware this is a temporary workaround for v5's new text engine and which will be improved in v6.
In summary, you drag import an image to a Tinderbox major view after which you can use it either as a source to copy paste the image to existing notes or add further data to the new note and treat it like any other note.
To create an image note, select a supported image format file in Finder and drag it into a Map, Outline view (but not other major views). A new note will be created with the image embedded in the $Text of the note. The note is otherwise a normal note and can be moved around, renamed and have additional text added to $Text without affecting the image.
Once imported in this fashion, the image can then be selected/copied from the new note and pasted into other note(s). To create a note with multiple images, import each image as a separate note and copy/cut paste the data as necessary.
Images embedded in note $Text cannot be cropped, scaled or otherwise resized (thus unlike image adornments). Select the desired image size before adding the image file to Tinderbox.
HTML Export. Unlike in older versions, these pictures can cannot be exported (or rather the HTML for them is exported but not the pictures!). For the latter reason do not embed pictures in notes you intend to support, or take action to add external, suitably named, copies the of the inline pictures to the relevant OS folders after HTML export. It is expected this anomaly in export will be resolved in v6 but not before.
If the TBX is primarily intended for export - like this document - it may make more sense to store the images outside the TBX and link the exported pages to the external assets. Given that embedded images do not export )at least not in v5.x) then it is possible for a note to have both an embedded image for viewing within tinderbox and alongside it export code that links to an externally stored coy of the image for use in HTML.
Image embedding was suspended in v5.0.0 through v5.8.1. Image insertion into notes was restored to partial support support status (see Release Notes) from v5.9.0, as described above.
NOTE: the change of text engine in Tinderbox v5.0.0 meant subsequent versions before v5.9.0 won't initially 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.
Legacy information. Tinderbox compresses images; this substantially decreases the size of Tinderbox files with embedded images. Tinderbox currently uses JPEG compression, and compresses fairly aggressively; this significantly diminishes the size and loading time of Tinderbox files at the cost of some image degradation.