Copying image files with HTML output

When building HTML ouput, texi2any expects to find image files in the
same directory as the .texi input files, but for the HTML to be
rendered correctly, they need to be in the same directory as the
output files. These are generally different directories.

According to the manual, "Image files referred to from the Texinfo
manual, if found, are copied to subdirectories of the container
directory", but this is only for EPUB output.  Shouldn't this happen
for HTML output as well?  If not, how is this normally handled?

My image files are generated, so I don't have an explicit list of
files, but I can still copy them easily enough because they're the
only jpg files in the source directory.  It could be more complicated
in other situations I imagine and in the end texi2any is best placed
to take care of this, as it knows which the files in question are.

Dimitris