[rt #94292] add jpeg_optimize to enable optimized Huffman tables

This can significantly reduce file size, but uses more memory and time.

For one sample image (mostly sky), this reduced the file size from
445930 bytes to 272933 bytes, with a 12% increase in CPU usage.

diff --git a/JPEG/JPEG.pm b/JPEG/JPEG.pm
index 9546596d9c2927949025e90643858f45aef41249..97dd9cf93b4658698eac5e370cdfae0e4308f67e 100644 (file)
--- a/JPEG/JPEG.pm
+++ b/JPEG/JPEG.pm
@@ -4,7 +4,7 @@ use Imager;
 use vars qw($VERSION @ISA);
 
 BEGIN {
-  $VERSION = "0.88";
+  $VERSION = "0.89";
 
   require XSLoader;
   XSLoader::load('Imager::File::JPEG', $VERSION);

diff --git a/JPEG/imjpeg.c b/JPEG/imjpeg.c
index b1c97d208a788a4ae77c047a4ecdf6e14bb875cc..dcb0ed639c3683cf78315376c2d6e14f9b330f03 100644 (file)
--- a/JPEG/imjpeg.c
+++ b/JPEG/imjpeg.c
@@ -566,6 +566,7 @@ i_writejpeg_wiol(i_img *im, io_glue *ig, int qfactor) {
   int comment_entry;
   int want_channels = im->channels;
   int progressive = 0;
+  int optimize = 0;
 
   struct jpeg_compress_struct cinfo;
   struct my_error_mgr jerr;
@@ -627,6 +628,9 @@ i_writejpeg_wiol(i_img *im, io_glue *ig, int qfactor) {
   if (progressive) {
     jpeg_simple_progression(&cinfo);
   }
+  if (!i_tags_get_int(&im->tags, "jpeg_optimize", 0, &optimize))
+    optimize = 0;
+  cinfo.optimize_coding = optimize;
 
   got_xres = i_tags_get_float(&im->tags, "i_xres", 0, &xres);
   got_yres = i_tags_get_float(&im->tags, "i_yres", 0, &yres);

diff --git a/JPEG/t/t10jpeg.t b/JPEG/t/t10jpeg.t
index 61c54dc5a977e6fb8c63c03c5fd83eee9b56a2ff..3408f068be064c009e8872594559221ff82f2818 100644 (file)
--- a/JPEG/t/t10jpeg.t
+++ b/JPEG/t/t10jpeg.t
@@ -11,7 +11,7 @@ init_log("testout/t101jpeg.log",1);
 $Imager::formats{"jpeg"}
   or plan skip_all => "no jpeg support";
 
-plan tests => 103;
+plan tests => 109;
 
 print STDERR "libjpeg version: ", Imager::File::JPEG::i_libjpeg_version(), "\n";
 
@@ -438,6 +438,25 @@ SKIP:
   is_image($rdprog, $norm, "prog vs norm should be the same image");
 }
 
+SKIP:
+{ # optimize coding
+  my $im = test_image();
+  my $base;
+  ok($im->write(data => \$base, type => "jpeg"), "save without optimize");
+  my $opt;
+  ok($im->write(data => \$opt, type => "jpeg", jpeg_optimize => 1),
+     "save with optimize");
+  cmp_ok(length $opt, '<', length $base, "check optimized is smaller");
+  my $im_base = Imager->new(data => $base, filetype => "jpeg");
+  ok($im_base, "read unoptimized back");
+  my $im_opt = Imager->new(data => $opt, filetype => "jpeg");
+  ok($im_opt, "read optimized back");
+  $im_base && $im_opt
+    or skip "couldn't read one back", 1;
+  is_image($im_opt, $im_base,
+          "optimization should only change huffman compression, not quality");
+}
+
 { # check close failures are handled correctly
   my $im = test_image();
   my $fail_close = sub {

diff --git a/lib/Imager/Files.pod b/lib/Imager/Files.pod
index 91e79f2e097e10b35f2b1b79407244d1432c45d0..5dc8aa10a152425721347726fed01941f2542184 100644 (file)
--- a/lib/Imager/Files.pod
+++ b/lib/Imager/Files.pod
@@ -647,6 +647,18 @@ file. (Imager 0.84)
 JPEG supports the spatial resolution tags C<i_xres>, C<i_yres> and
 C<i_aspect_only>.
 
+You can also set the following tags when writing to an image, they are
+not set in the image when reading:
+
+=over
+
+C<jpeg_optimize> - set to a non-zero integer to compute optimal
+Huffman coding tables for the image.  This will increase memory usage
+and processing time (about 12% in my simple tests) but can
+significantly reduce file size without a loss of quality.
+
+=back
+
 =for stopwords EXIF
 
 If an C<APP1> block containing EXIF information is found, then any of the