Image data is returned if a request successfully completes, and if the request either does not include a req= command, or if req=img or req=tmb.
The HTTP response MIME type is determined by fmt=
, or, if fmt=
is not specified, it is <image/jpeg>
.
The HTTP response status is ‘200 OK’ if the request method was an unconditional GET
or HEAD
.
The server may reply with status ‘304’ (not modified) and not return any image data in response to a conditional GET
request (which includes a valid If-Modified-Since
or If-None-Match
header).