For efficiency, DocView caches the images produced by gs.
The name of the directory where it caches images is given by the variable
doc-view-cache-directory. You can clear the cache directory by
typing M-x doc-view-clear-cache.
To force reconversion of the currently viewed document, type r
or g (
revert-buffer). To kill the converter process
associated with the current buffer, type K
doc-view-kill-proc). The command k
doc-view-kill-proc-and-buffer) kills the converter process and
the DocView buffer.