An example for three figures at 150px but otherwise with the default settings, followed by the markup generated.
{{{#!gallery 150px [markup] test.png:: Image 1 test.png:: Image 2 test.png:: Image 3 }}}
||<: tablestyle="width:10%" height="170px" width="170px" bgcolor="#e8e8e8">[[#|{{attachment:/test.png|click for original|height=150,width=150}}|target="_blank",&action=AttachFile,&do=get,&target="test.png"]]||<width="20px" style="border:none;">||<: height="170px" width="170px" bgcolor="#e8e8e8">[[#|{{attachment:/test.png|click for original|height=150,width=150}}|target="_blank",&action=AttachFile,&do=get,&target="test.png"]]||<width="20px" style="border:none;">||<: height="170px" width="170px" bgcolor="#e8e8e8">[[#|{{attachment:/test.png|click for original|height=150,width=150}}|target="_blank",&action=AttachFile,&do=get,&target="test.png"]]|| ||<^ style="border:none;">Image 1||<style="border:none;">||<^ style="border:none;">Image 2||<style="border:none;">||<^ style="border:none;">Image 3||
Examples of vertical {{{#!gallery c-2 320px pdf-vert ...}}} and horizontal {{{#!gallery c-2 450px pdf-horz ...}}} format PDFs.