is there a function getFilterSpec for images

Is there a function like

      formats_vid = VideoReader.getFileFormats();
      filterSpec_vid = getFilterSpec(formats_vid,'video');

for the output from

      x=imformats

so far I have

        y=strcat('*,',char([y.ext]), ';')

but i need to get that to '*.bmp;*.cur;*.fts...'