PD4ML loads document resources (even from a local file system) using URL/URLConnection Java classes. If an image is referenced using a file system path, it is implicitly converted to an URL by an adding a “file:” protocol prefix.
‘#’ symbol has a special meaning in URLs. In your particular case ‘#’ and following it path info is simply ignored.
It is important to understand, that from HTML specification perspective your HTML code is erroneous. The specification explicitly requires to use an URL (not just a path) as an SRC attribute value:
valid non-empty URL potentially surrounded by spaces referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted.
The major web browsers also accept paths to workaround a “popular” web authors’ mistake. (However with MS FrontPage it is even impossible to embed an image from a directory with ‘#’ in its name).
We could implement a support of ‘#’ in image paths, but probably a renaming of the dir to a web-friendly name is a better idea.