Temp fix for #138

Disable scan optimization and trellis quantization when arithmetic
coding is used

jpegtran.c

@@ -175,6 +175,12 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
       /* Use arithmetic coding. */
 #ifdef C_ARITH_CODING_SUPPORTED
       cinfo->arith_code = TRUE;
+
+      /* No table optimization required for AC */
+      cinfo->optimize_coding = FALSE;
+      
+      /* Scan optimization currently incompatible with AC */
+      jpeg_c_set_bool_param(cinfo, JBOOLEAN_OPTIMIZE_SCANS, FALSE);
 #else
       fprintf(stderr, "%s: sorry, arithmetic coding not supported\n",
               progname);