Back-port code from jpeg-8 that removes unpopulated (and unneeded) tables for AC and DC coefficients when generating progressive JPEG files with arithmetic coding. This should make such files bitwise compatible with jpeg-8, barring any other mathematical differences listed in README-turbo.txt. Add regression tests for progressive+arithmetic JPEG files.

CMakeLists.txt

@@ -309,6 +309,7 @@ set(MD5_BMP_256 4980185e3776e89bd931736e1cddeee6)
 set(MD5_JPEG_ARI e986fb0a637a8d833d96e8a6d6d84ea1)
 set(MD5_PPM_ARI 72b59a99bcf1de24c5b27d151bde2437)
 set(MD5_JPEG_PROG 1c4afddc05c0a43489ee54438a482d92)
+set(MD5_JPEG_PROG_ARI 0a8f1c8f66e113c3cf635df0a475a617)
 set(MD5_JPEG_CROP b4197f377e621c4e9b1d20471432610d)
 
 if(WITH_JAVA)
@@ -366,6 +367,8 @@ add_test(cjpeg-ari sharedlib/cjpeg -dct int -arithmetic -outfile testoutari.jpg
 add_test(cjpeg-ari-cmp ${CMAKE_COMMAND} -DMD5=${MD5_JPEG_ARI} -DFILE=testoutari.jpg -P ${CMAKE_SOURCE_DIR}/cmakescripts/md5cmp.cmake )
 add_test(jpegtran-toari sharedlib/jpegtran -arithmetic -outfile testouta.jpg ${CMAKE_SOURCE_DIR}/testimages/testimgint.jpg)
 add_test(jpegtran-toari-cmp ${CMAKE_COMMAND} -DMD5=${MD5_JPEG_ARI} -DFILE=testouta.jpg -P ${CMAKE_SOURCE_DIR}/cmakescripts/md5cmp.cmake)
+add_test(cjpeg-prog-ari sharedlib/cjpeg -dct int -progressive -arithmetic -sample 1x1 -outfile testoutpa.jpg ${CMAKE_SOURCE_DIR}/testimages/testorig.ppm)
+add_test(cjpeg-prog-ari-cmp ${CMAKE_COMMAND} -DMD5=${MD5_JPEG_PROG_ARI} -DFILE=testoutpa.jpg -P ${CMAKE_SOURCE_DIR}/cmakescripts/md5cmp.cmake )
 endif()
 if(WITH_ARITH_DEC)
 add_test(djpeg-ari sharedlib/djpeg -dct int -fast -ppm -outfile testoutari.ppm ${CMAKE_SOURCE_DIR}/testimages/testimgari.jpg)
@@ -423,6 +426,8 @@ add_test(cjpeg-static-ari cjpeg-static -dct int -arithmetic -outfile testoutari.
 add_test(cjpeg-static-ari-cmp ${CMAKE_COMMAND} -DMD5=${MD5_JPEG_ARI} -DFILE=testoutari.jpg -P ${CMAKE_SOURCE_DIR}/cmakescripts/md5cmp.cmake )
 add_test(jpegtran-static-toari jpegtran-static -arithmetic -outfile testouta.jpg ${CMAKE_SOURCE_DIR}/testimages/testimgint.jpg)
 add_test(jpegtran-static-toari-cmp ${CMAKE_COMMAND} -DMD5=${MD5_JPEG_ARI} -DFILE=testouta.jpg -P ${CMAKE_SOURCE_DIR}/cmakescripts/md5cmp.cmake)
+add_test(cjpeg-static-prog-ari cjpeg-static -dct int -progressive -arithmetic -sample 1x1 -outfile testoutpa.jpg ${CMAKE_SOURCE_DIR}/testimages/testorig.ppm)
+add_test(cjpeg-static-prog-ari-cmp ${CMAKE_COMMAND} -DMD5=${MD5_JPEG_PROG_ARI} -DFILE=testoutpa.jpg -P ${CMAKE_SOURCE_DIR}/cmakescripts/md5cmp.cmake )
 endif()
 if(WITH_ARITH_DEC)
 add_test(djpeg-static-ari djpeg-static -dct int -fast -ppm -outfile testoutari.ppm ${CMAKE_SOURCE_DIR}/testimages/testimgari.jpg)

Makefile.am

@@ -192,6 +192,7 @@ MD5_BMP_256 = 4980185e3776e89bd931736e1cddeee6
 MD5_JPEG_ARI = e986fb0a637a8d833d96e8a6d6d84ea1
 MD5_PPM_ARI = 72b59a99bcf1de24c5b27d151bde2437
 MD5_JPEG_PROG = 1c4afddc05c0a43489ee54438a482d92
+MD5_JPEG_PROG_ARI = 0a8f1c8f66e113c3cf635df0a475a617
 MD5_JPEG_CROP = b4197f377e621c4e9b1d20471432610d
 
 test: testclean all
@@ -273,6 +274,8 @@ if WITH_ARITH_ENC
 	md5/md5cmp $(MD5_JPEG_ARI) testoutari.jpg
 	./jpegtran -arithmetic -outfile testouta.jpg $(srcdir)/testimages/testimgint.jpg
 	md5/md5cmp $(MD5_JPEG_ARI) testouta.jpg
+	./cjpeg -dct int -progressive -arithmetic -sample 1x1 -outfile testoutpa.jpg $(srcdir)/testimages/testorig.ppm
+	md5/md5cmp $(MD5_JPEG_PROG_ARI) testoutpa.jpg
 endif
 if WITH_ARITH_DEC
 	./djpeg -dct int -fast -ppm -outfile testoutari.ppm $(srcdir)/testimages/testimgari.jpg

jcmarker.c

@@ -239,26 +239,32 @@ emit_dac (j_compress_ptr cinfo)
 
   for (i = 0; i < cinfo->comps_in_scan; i++) {
     compptr = cinfo->cur_comp_info[i];
-    dc_in_use[compptr->dc_tbl_no] = 1;
+    /* DC needs no table for refinement scan */
-    ac_in_use[compptr->ac_tbl_no] = 1;
+    if (cinfo->Ss == 0 && cinfo->Ah == 0)
+      dc_in_use[compptr->dc_tbl_no] = 1;
+    /* AC needs no table when not present */
+    if (cinfo->Se)
+      ac_in_use[compptr->ac_tbl_no] = 1;
   }
 
   length = 0;
   for (i = 0; i < NUM_ARITH_TBLS; i++)
     length += dc_in_use[i] + ac_in_use[i];
 
-  emit_marker(cinfo, M_DAC);
+  if (length) {
+    emit_marker(cinfo, M_DAC);
 
-  emit_2bytes(cinfo, length*2 + 2);
+    emit_2bytes(cinfo, length*2 + 2);
 
-  for (i = 0; i < NUM_ARITH_TBLS; i++) {
+    for (i = 0; i < NUM_ARITH_TBLS; i++) {
-    if (dc_in_use[i]) {
+      if (dc_in_use[i]) {
-      emit_byte(cinfo, i);
+	emit_byte(cinfo, i);
-      emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
+	emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
-    }
+      }
-    if (ac_in_use[i]) {
+      if (ac_in_use[i]) {
-      emit_byte(cinfo, i + 0x10);
+	emit_byte(cinfo, i + 0x10);
-      emit_byte(cinfo, cinfo->arith_ac_K[i]);
+	emit_byte(cinfo, cinfo->arith_ac_K[i]);
+      }
     }
   }
 #endif /* C_ARITH_CODING_SUPPORTED */
@@ -324,22 +330,16 @@ emit_sos (j_compress_ptr cinfo)
   for (i = 0; i < cinfo->comps_in_scan; i++) {
     compptr = cinfo->cur_comp_info[i];
     emit_byte(cinfo, compptr->component_id);
-    td = compptr->dc_tbl_no;
+
-    ta = compptr->ac_tbl_no;
+    /* We emit 0 for unused field(s); this is recommended by the P&M text
-    if (cinfo->progressive_mode) {
+     * but does not seem to be specified in the standard.
-      /* Progressive mode: only DC or only AC tables are used in one scan;
+     */
-       * furthermore, Huffman coding of DC refinement uses no table at all.
+
-       * We emit 0 for unused field(s); this is recommended by the P&M text
+    /* DC needs no table for refinement scan */
-       * but does not seem to be specified in the standard.
+    td = cinfo->Ss == 0 && cinfo->Ah == 0 ? compptr->dc_tbl_no : 0;
-       */
+    /* AC needs no table when not present */
-      if (cinfo->Ss == 0) {
+    ta = cinfo->Se ? compptr->ac_tbl_no : 0;
-	ta = 0;			/* DC scan */
+
-	if (cinfo->Ah != 0 && !cinfo->arith_code)
-	  td = 0;		/* no DC table either */
-      } else {
-	td = 0;			/* AC scan */
-      }
-    }
     emit_byte(cinfo, (td << 4) + ta);
   }
 
@@ -573,19 +573,12 @@ write_scan_header (j_compress_ptr cinfo)
      */
     for (i = 0; i < cinfo->comps_in_scan; i++) {
       compptr = cinfo->cur_comp_info[i];
-      if (cinfo->progressive_mode) {
+      /* DC needs no table for refinement scan */
-	/* Progressive mode: only DC or only AC tables are used in one scan */
+      if (cinfo->Ss == 0 && cinfo->Ah == 0)
-	if (cinfo->Ss == 0) {
-	  if (cinfo->Ah == 0)	/* DC needs no table for refinement scan */
-	    emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
-	} else {
-	  emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
-	}
-      } else {
-	/* Sequential mode: need both DC and AC tables */
 	emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
+      /* AC needs no table when not present */
+      if (cinfo->Se)
 	emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
-      }
     }
   }