Implement arithmetic coding with 12-bit precision

This actually works and apparently always has worked.  It only failed
because the libjpeg code, which did not originally support arithmetic
coding, assumed that optimize_coding should always be TRUE for 12-bit
data precision.

java/TJBench.java

@@ -775,6 +775,7 @@ final class TJBench {
     System.out.println("     (use the CMYK pixel format for packed-pixel source/destination buffers)");
     System.out.println("-precision N = Use N-bit data precision when compressing [N is 8, 12, or 16;");
     System.out.println("     default = 8; if N is 16, then -lossless must also be specified]");
+    System.out.println("     (-precision 12 implies -optimize unless -arithmetic is also specified)");
     System.out.println("-quiet = Output results in tabular rather than verbose format");
     System.out.println("-restart N = When compressing, add a restart marker every N MCU rows (lossy) or");
     System.out.println("     N sample rows (lossless) [default = 0 (no restart markers)].  Append 'B'");
@@ -793,7 +794,6 @@ final class TJBench {
     System.out.println("------------------");
     System.out.println("-arithmetic = Use arithmetic entropy coding in JPEG images generated by");
     System.out.println("     compression and transform operations (can be combined with -progressive)");
-    System.out.println("     ** 8-bit data precision only **");
     System.out.println("-crop WxH+X+Y = Decompress only the specified region of the JPEG image, where W");
     System.out.println("     and H are the width and height of the region (0 = maximum possible width");
     System.out.println("     or height) and X and Y are the left and upper boundary of the region, all");
@@ -804,8 +804,8 @@ final class TJBench {
     System.out.println("-optimize = Use optimized baseline entropy coding in JPEG images generated by");
     System.out.println("     compession and transform operations");
     System.out.println("-progressive = Use progressive entropy coding in JPEG images generated by");
-    System.out.println("     compression and transform operations (implies -optimize; can be combined");
-    System.out.println("     with -arithmetic)");
+    System.out.println("     compression and transform operations (can be combined with -arithmetic;");
+    System.out.println("     implies -optimize unless -arithmetic is also specified)");
     System.out.println("-limitscans = Refuse to decompress or transform progressive JPEG images that");
     System.out.println("     have an unreasonably large number of scans");
     System.out.println("-scale M/N = When decompressing, scale the width/height of the JPEG image by a");
@@ -1087,8 +1087,6 @@ final class TJBench {
 
       if (precision == 16 && !lossless)
         throw new Exception("-lossless must be specified along with -precision 16");
-      if (precision != 8 && arithmetic)
-        throw new Exception("-arithmetic requires 8-bit data precision");
       if (precision != 8 && doYUV)
         throw new Exception("-yuv requires 8-bit data precision");
       if (lossless && doYUV)

java/doc/org/libjpegturbo/turbojpeg/TJ.html

@@ -1367,7 +1367,8 @@ extends java.lang.Object</pre>
  <li> <code>8</code>, <code>12</code>, or <code>16</code>
  </ul>
 
- <p>12-bit data precision implies <a href="#PARAM_OPTIMIZE"><code>PARAM_OPTIMIZE</code></a>.</div>
+ <p>12-bit data precision implies <a href="#PARAM_OPTIMIZE"><code>PARAM_OPTIMIZE</code></a> unless
+ <a href="#PARAM_ARITHMETIC"><code>PARAM_ARITHMETIC</code></a> is set.</div>
 <dl>
 <dt><span class="seeLabel">See Also:</span></dt>
 <dd><a href="../../../constant-values.html#org.libjpegturbo.turbojpeg.TJ.PARAM_PRECISION">Constant Field Values</a></dd>
@@ -1511,8 +1512,9 @@ extends java.lang.Object</pre>
 
  <p>Progressive entropy coding will generally improve compression relative
  to baseline entropy coding, but it will reduce compression and
- decompression performance considerably.  Implies <a href="#PARAM_OPTIMIZE"><code>PARAM_OPTIMIZE</code></a>.
- Can be combined with <a href="#PARAM_ARITHMETIC"><code>PARAM_ARITHMETIC</code></a>.</div>
+ decompression performance considerably.  Can be combined with
+ <a href="#PARAM_ARITHMETIC"><code>PARAM_ARITHMETIC</code></a>.  Implies <a href="#PARAM_OPTIMIZE"><code>PARAM_OPTIMIZE</code></a> unless
+ <a href="#PARAM_ARITHMETIC"><code>PARAM_ARITHMETIC</code></a> is also set.</div>
 <dl>
 <dt><span class="seeLabel">See Also:</span></dt>
 <dd><a href="../../../constant-values.html#org.libjpegturbo.turbojpeg.TJ.PARAM_PROGRESSIVE">Constant Field Values</a></dd>
@@ -1572,8 +1574,7 @@ extends java.lang.Object</pre>
  <p>Arithmetic entropy coding will generally improve compression relative
  to Huffman entropy coding, but it will reduce compression and
  decompression performance considerably.  Can be combined with
- <a href="#PARAM_PROGRESSIVE"><code>PARAM_PROGRESSIVE</code></a>.  Arithmetic entropy coding is currently only
- implemented for 8-bit samples.</div>
+ <a href="#PARAM_PROGRESSIVE"><code>PARAM_PROGRESSIVE</code></a>.</div>
 <dl>
 <dt><span class="seeLabel">See Also:</span></dt>
 <dd><a href="../../../constant-values.html#org.libjpegturbo.turbojpeg.TJ.PARAM_ARITHMETIC">Constant Field Values</a></dd>

java/doc/org/libjpegturbo/turbojpeg/TJTransform.html

@@ -700,8 +700,8 @@ extends java.awt.Rectangle</pre>
  generated by this particular transform.  Progressive entropy coding will
  generally improve compression relative to baseline entropy coding (the
  default), but it will reduce decompression performance considerably.
- Implies <a href="#OPT_OPTIMIZE"><code>OPT_OPTIMIZE</code></a>.  Can be combined with
- <a href="#OPT_ARITHMETIC"><code>OPT_ARITHMETIC</code></a>.</div>
+ Can be combined with <a href="#OPT_ARITHMETIC"><code>OPT_ARITHMETIC</code></a>.  Implies
+ <a href="#OPT_OPTIMIZE"><code>OPT_OPTIMIZE</code></a> unless <a href="#OPT_ARITHMETIC"><code>OPT_ARITHMETIC</code></a> is also specified.</div>
 <dl>
 <dt><span class="seeLabel">See Also:</span></dt>
 <dd><a href="../../../constant-values.html#org.libjpegturbo.turbojpeg.TJTransform.OPT_PROGRESSIVE">Constant Field Values</a></dd>

java/org/libjpegturbo/turbojpeg/TJ.java

@@ -465,7 +465,8 @@ public final class TJ {
    * <li> <code>8</code>, <code>12</code>, or <code>16</code>
    * </ul>
    *
-   * <p>12-bit data precision implies {@link #PARAM_OPTIMIZE}.
+   * <p>12-bit data precision implies {@link #PARAM_OPTIMIZE} unless
+   * {@link #PARAM_ARITHMETIC} is set.
    */
   public static final int PARAM_PRECISION = 7;
   /**
@@ -559,8 +560,9 @@ public final class TJ {
    *
    * <p>Progressive entropy coding will generally improve compression relative
    * to baseline entropy coding, but it will reduce compression and
-   * decompression performance considerably.  Implies {@link #PARAM_OPTIMIZE}.
-   * Can be combined with {@link #PARAM_ARITHMETIC}.
+   * decompression performance considerably.  Can be combined with
+   * {@link #PARAM_ARITHMETIC}.  Implies {@link #PARAM_OPTIMIZE} unless
+   * {@link #PARAM_ARITHMETIC} is also set.
    */
   public static final int PARAM_PROGRESSIVE = 12;
   /**
@@ -601,8 +603,7 @@ public final class TJ {
    * <p>Arithmetic entropy coding will generally improve compression relative
    * to Huffman entropy coding, but it will reduce compression and
    * decompression performance considerably.  Can be combined with
-   * {@link #PARAM_PROGRESSIVE}.  Arithmetic entropy coding is currently only
-   * implemented for 8-bit samples.
+   * {@link #PARAM_PROGRESSIVE}.
    */
   public static final int PARAM_ARITHMETIC = 14;
   /**

java/org/libjpegturbo/turbojpeg/TJTransform.java

@@ -133,8 +133,8 @@ public class TJTransform extends Rectangle {
    * generated by this particular transform.  Progressive entropy coding will
    * generally improve compression relative to baseline entropy coding (the
    * default), but it will reduce decompression performance considerably.
-   * Implies {@link #OPT_OPTIMIZE}.  Can be combined with
-   * {@link #OPT_ARITHMETIC}.
+   * Can be combined with {@link #OPT_ARITHMETIC}.  Implies
+   * {@link #OPT_OPTIMIZE} unless {@link #OPT_ARITHMETIC} is also specified.
    */
   public static final int OPT_PROGRESSIVE = (1 << 5);
   /**