It says it is optional here:

  http://backend.userland.com/rss091

Also, please refer to the DTD here:

  http://my.netscape.com/publish/formats/rss-0.91.dtd

Which says:

  <!ELEMENT channel (title | description | link | language | item+ | rating? | image? | ...


Unless I completely misread the DTD, <image> is as optional as <rating>.

Could this be corrected, please?

Thanks!
Sam