diff --git a/chertex.sh b/chertex.sh
index 52732fb..7a3bc45 100755
--- a/chertex.sh
+++ b/chertex.sh
@@ -93,7 +93,7 @@ if [ $# -eq 1 ]; then
       echo "<thesis> -------------------------------"
       echo "<thesis> Getting external assets"
       echo "<thesis> -------------------------------"
-		  # summary of operations in this if-clause:
+		# summary of operations in this if-clause:
       # trawl the assets/ subdirectories looking for a file "external.assets", if found,
       # read its contents line-by-line (each line is a path) and copy that file at that path to the current assets/ subdir
       # note that we only look for assets.external inside the subdirectories, and not in assets/ itself
@@ -150,16 +150,24 @@ if [ $# -eq 1 ]; then
          largephototype=${largephotobase#*.} # file extension only
          largephotoname=${largephotofilename%.*} # path without extension
          largephotobasename=${largephotobase%.*} # basename without extension
-         if [ ! "$largephototype" == "jpg" ] && [ ! "$largephototype" == "jpeg" ] && [ ! "$largephototype" == "JPG" ] && [ ! "$largephototype" == "JPEG" ]; then
-            echo "<thesis> Converting $largephotobase to JPG format"
-            mogrify -format jpg $largephotofilename
-            # remove the now unnecessary non-jpg file from .lowres/
-            rm "$largephotofilename"
+         # some filetypes don't fare well when converted to jpeg, so we will only run the 
+         # forced conversion and shrinking unless the file extension is one of the following:
+         # "" (empty string, ie no file extension)
+         # SVG
+         # PDF
+         if [ ! "$largephototype" == "" ] || [ ! "$largephototype" == "svg" ] || [ ! "$largephototype" == "SVG" ] || [ ! "$largephototype" == "pdf" ] || [ ! "$largephototype" == "PDF" ]; then
+            # if the photo is not already jpeg, convert it to jpeg
+            if [ ! "$largephototype" == "jpg" ] && [ ! "$largephototype" == "jpeg" ] && [ ! "$largephototype" == "JPG" ] && [ ! "$largephototype" == "JPEG" ]; then
+               echo "<thesis> Converting $largephotobase to JPG format"
+               mogrify -format jpg $largephotofilename
+               # remove the now unnecessary non-jpg file from .lowres/
+               rm "$largephotofilename"
+            fi
+            # convert photo in-place (overwrite) with new one roughly 300kb in size
+            # https://stackoverflow.com/questions/6917219/imagemagick-scale-jpeg-image-with-a-maximum-file-size
+            echo "<thesis> Shrinking $largephotobasename.jpg"
+            convert $largephotoname.jpg -define jpeg:extent=300kb $largephotoname.jpg
          fi
-         # convert photo in-place (overwrite) with new one roughly 300kb in size
-         # https://stackoverflow.com/questions/6917219/imagemagick-scale-jpeg-image-with-a-maximum-file-size
-         echo "<thesis> Shrinking $largephotobasename.jpg"
-         convert $largephotoname.jpg -define jpeg:extent=300kb $largephotoname.jpg
       done
       # update the modification and access time on the photosastrun file
       touch "$photoslastrun"