TurboJPEG: Fix 12-bit-per-sample arith-coded compr

(Regression introduced by 7bb958b732e6b4f261595e2d1527d46964fe3aed)

Because of 7bb958b732e6b4f261595e2d1527d46964fe3aed, the TurboJPEG
compression and encoding functions no longer transfer the value of
TJPARAM_OPTIMIZE into cinfo->data_precision unless the data precision
is 8.  The intent of that was to prevent using_std_huff_tables() from
being called more than once when reusing the same compressor object to
generate multiple 12-bit-per-sample JPEG images.  However, because
cinfo->optimize_coding is always set to TRUE by jpeg_set_defaults() if
the data precision is 12, calling applications that use 12-bit data
precision had to unset cinfo->optimize_coding if they set
cinfo->arith_code after calling jpeg_set_defaults().  Because of
7bb958b732e6b4f261595e2d1527d46964fe3aed, the TurboJPEG API stopped
doing that except with 8-bit data precision.  Thus, attempting to
generate a 12-bit-per-sample arithmetic-coded lossy JPEG image using
the TurboJPEG API failed with "Requested features are incompatible."

Since the compressor will always fail if cinfo->arith_code and
cinfo->optimize_coding are both set, and since cinfo->optimize_coding
has no relevance for arithmetic coding, the most robust and user-proof
solution is for jinit_c_master_control() to set cinfo->optimize_coding
to FALSE if cinfo->arith_code is TRUE.

This commit also:
- modifies TJBench so that it no longer reports that it is using
  optimized baseline entropy coding in modes where that setting
  is irrelevant,
- amends the cjpeg documentation to clarify that -optimize is implied
  when specifying -progressive or '-precision 12' without -arithmetic,
  and
- prevents jpeg_set_defaults() from uselessly checking the value of
  cinfo->arith_code immediately after it has been set to FALSE.

ChangeLog.md

@@ -24,6 +24,10 @@ response to a prematurely-terminated JPEG data stream.
 greater than 7 resulted in an error ("Invalid progressive/lossless parameters")
 unless the `-precision` option was specified before the `-lossless` option.
 
+4. Fixed a regression introduced by 3.0.3[3] that made it impossible for
+calling applications to generate 12-bit-per-sample arithmetic-coded lossy JPEG
+images using the TurboJPEG API.
+
 
 3.0.3
 =====

cjpeg.1

@@ -1,4 +1,4 @@
-.TH CJPEG 1 "21 June 2024"
+.TH CJPEG 1 "24 June 2024"
 .SH NAME
 cjpeg \- compress an image file to a JPEG file
 .SH SYNOPSIS
@@ -60,7 +60,11 @@ decompression are unaffected by
 .BR \-optimize .
 .TP
 .B \-progressive
-Create progressive JPEG file (see below).
+Create progressive JPEG file (see below).  Implies
+.B \-optimize
+unless
+.B \-arithmetic
+is also specified.
 .TP
 .B \-targa
 Input file is Targa format [legacy feature].  Targa files that contain an
@@ -168,6 +172,13 @@ will cause it to print information about the precision of the input file.
 12-bit and 16-bit data precision is not yet widely implemented, so many
 decoders will be unable to handle a 12-bit-per-sample or 16-bit-per-sample JPEG
 file at all.
+.IP
+.B \-precision\ 12
+implies
+.B \-optimize
+unless
+.B \-arithmetic
+is also specified.
 .TP
 .BI \-lossless " psv[,Pt]"
 Create a lossless JPEG file using the specified predictor selection value

java/TJBench.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C)2009-2014, 2016-2019, 2021-2023 D. R. Commander.
+ * Copyright (C)2009-2014, 2016-2019, 2021-2024 D. R. Commander.
  *                                              All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -926,7 +926,6 @@ final class TJBench {
             System.out.println("Using fastest DCT/IDCT algorithm\n");
             fastDCT = true;
           } else if (argv[i].equalsIgnoreCase("-optimize")) {
-            System.out.println("Using optimized baseline entropy coding\n");
             optimize = true;
             xformOpt |= TJTransform.OPT_OPTIMIZE;
           } else if (argv[i].equalsIgnoreCase("-progressive")) {
@@ -1127,6 +1126,10 @@ final class TJBench {
         }
       }
 
+      if (optimize && !progressive && !arithmetic && !lossless &&
+          precision != 12)
+        System.out.println("Using optimized baseline entropy coding\n");
+
       if (precision == 16 && !lossless)
         throw new Exception("-lossless must be specified along with -precision 16");
       if (precision != 8 && doYUV)

jcmaster.c

@@ -751,22 +751,25 @@ jinit_c_master_control(j_compress_ptr cinfo, boolean transcode_only)
   /* Validate parameters, determine derived values */
   initial_setup(cinfo, transcode_only);
 
-  if (cinfo->master->lossless ||        /*  TEMPORARY HACK ??? */
-      (cinfo->progressive_mode && !cinfo->arith_code))
-    cinfo->optimize_coding = TRUE; /* assume default tables no good for
-                                      progressive mode or lossless mode */
-  for (i = 0; i < NUM_HUFF_TBLS; i++) {
-    if (cinfo->dc_huff_tbl_ptrs[i] != NULL ||
-        cinfo->ac_huff_tbl_ptrs[i] != NULL) {
-      empty_huff_tables = FALSE;
-      break;
+  if (cinfo->arith_code)
+    cinfo->optimize_coding = FALSE;
+  else {
+    if (cinfo->master->lossless ||      /*  TEMPORARY HACK ??? */
+        cinfo->progressive_mode)
+      cinfo->optimize_coding = TRUE; /* assume default tables no good for
+                                        progressive mode or lossless mode */
+    for (i = 0; i < NUM_HUFF_TBLS; i++) {
+      if (cinfo->dc_huff_tbl_ptrs[i] != NULL ||
+          cinfo->ac_huff_tbl_ptrs[i] != NULL) {
+        empty_huff_tables = FALSE;
+        break;
+      }
     }
+    if (cinfo->data_precision == 12 && !cinfo->optimize_coding &&
+        (empty_huff_tables || using_std_huff_tables(cinfo)))
+      cinfo->optimize_coding = TRUE; /* assume default tables no good for
+                                        12-bit data precision */
   }
-  if (cinfo->data_precision == 12 && !cinfo->arith_code &&
-      !cinfo->optimize_coding &&
-      (empty_huff_tables || using_std_huff_tables(cinfo)))
-    cinfo->optimize_coding = TRUE; /* assume default tables no good for 12-bit
-                                      data precision */
 
   /* Initialize my private state */
   if (transcode_only) {

jcparam.c

@@ -233,7 +233,7 @@ jpeg_set_defaults(j_compress_ptr cinfo)
    * tables will be computed.  This test can be removed if default tables
    * are supplied that are valid for the desired precision.
    */
-  if (cinfo->data_precision == 12 && !cinfo->arith_code)
+  if (cinfo->data_precision == 12)
     cinfo->optimize_coding = TRUE;
 
   /* By default, use the simpler non-cosited sampling alignment */

libjpeg.txt

@@ -1141,10 +1141,11 @@ boolean optimize_coding
         Huffman tables.  In most cases optimal tables save only a few percent
         of file size compared to the default tables.  Note that when this is
         TRUE, you need not supply Huffman tables at all, and any you do
-        supply will be overwritten.  This parameter has no effect in
-        progressive mode or lossless mode, in which optimal Huffman tables are
-        always computed, and it defaults to TRUE for 12-bit data precision
-        unless Huffman tables have been supplied.
+        supply will be overwritten.  Optimal Huffman tables are always
+        computed, and this parameter has no effect, in progressive mode or
+        lossless mode or with 12-bit data precision (unless Huffman tables have
+        been supplied.)  This parameter also has no effect when using
+        arithmetic coding.
 
 unsigned int restart_interval
 int restart_in_rows

tjbench.c

@@ -1047,7 +1047,6 @@ int main(int argc, char *argv[])
         printf("Using fastest DCT/IDCT algorithm\n\n");
         fastDCT = 1;
       } else if (!strcasecmp(argv[i], "-optimize")) {
-        printf("Using optimized baseline entropy coding\n\n");
         optimize = 1;
         xformOpt |= TJXOPT_OPTIMIZE;
       } else if (!strcasecmp(argv[i], "-progressive")) {
@@ -1197,6 +1196,9 @@ int main(int argc, char *argv[])
     }
   }
 
+  if (optimize && !progressive && !arithmetic && !lossless && precision != 12)
+    printf("Using optimized baseline entropy coding\n\n");
+
   if (precision == 16 && !lossless) {
     printf("ERROR: -lossless must be specified along with -precision 16\n");
     retval = -1;  goto bailout;

usage.txt

@@ -91,7 +91,8 @@ The basic command line switches for cjpeg are:
                         memory.  Image quality and speed of decompression are
                         unaffected by -optimize.
 
-        -progressive    Create progressive JPEG file (see below).
+        -progressive    Create progressive JPEG file (see below).  Implies
+                        -optimize unless -arithmetic is also specified.
 
         -targa          Input file is Targa format [legacy feature].  Targa
                         files that contain an "identification" field will not
@@ -181,6 +182,9 @@ Switches for advanced users:
                        decoders will be unable to handle a 12-bit-per-sample or
                        16-bit-per-sample JPEG file at all.
 
+                       "-precision 12" implies -optimize unless -arithmetic is
+                       also specified.
+
         -lossless psv[,Pt] Create a lossless JPEG file using the specified
                         predictor selection value (1 - 7) and optional point
                         transform (0 - {precision}-1, where {precision} is the