--- loncom/cgi/plot.gif	2003/09/24 21:15:55	1.10
+++ loncom/cgi/plot.gif	2016/10/12 18:50:02	1.16
@@ -1,6 +1,6 @@
 #!/usr/bin/perl
 #
-# $Id: plot.gif,v 1.10 2003/09/24 21:15:55 matthew Exp $
+# $Id: plot.gif,v 1.16 2016/10/12 18:50:02 musolffc Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -37,21 +37,26 @@ foreach (split/&/,$ENV{'QUERY_STRING'})
 my $filename = $data{'file'};
 # unescape filename
 $filename =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
-
 die if ($filename =~ /\// || $filename !~ /_plot.data$/);
 $filename = $tmpdir . $filename;
 die "$data{'file'} does not exist\n" if (! -e $filename);
 
 my $output = $data{'output'};
-if ($output eq 'gif') {
-    open PLOT, "gnuplot $filename |";
+if ($output eq '') {
+    $output = (split('\.',$0))[-1];
+}
+
+if ($output eq 'gif' || $output eq 'png') {
+    open(my $plot, "gnuplot $filename |");
+
     print <<"END";
-Content-type: image/gif
+Content-type: image/$output
 
 END
-    while ($_=<PLOT>) {
-	print;
+    while (my $line = <$plot>) {
+	print($line);
     }
+
 } elsif ($output eq 'eps') {
     print <<"END";
 Content-type: text/html
@@ -62,7 +67,7 @@ Content-type: text/html
 
 END
     if (! system ("gnuplot $filename")) {
-        print "<h2>An error occured.</h2>\n".
+        print "<h2>An error occurred.</h2>\n".
             "I am not going to tell you about it as I have not bothered ".
             "to figure out how to get you the error text.\n";
     } else {
@@ -72,6 +77,3 @@ END
 } else {
     die "output $output is not a recognized value or has no value\n";
 }
-
-
-