Significantly improve grayscale performance

git-svn-id: svn://svn.code.sf.net/p/libjpeg-turbo/code/trunk@63 632fc199-4ca6-4c93-a231-07263d6284db

1 files changed, 87 insertions, 9 deletions

diff --git a/jccolor.c b/jccolor.c
index 8d3feb8..2e2bfd2 100644
--- a/jccolor.c
+++ b/jccolor.c
@@ -81,6 +81,74 @@ typedef my_color_converter * my_cconvert_ptr;
 #define TABLE_SIZE	(8*(MAXJSAMPLE+1))
 
 
+#if BITS_IN_JSAMPLE == 8
+
+const unsigned char red_lut[256] = {
+  0 , 0 , 1 , 1 , 1 , 1 , 2 , 2 , 2 , 3 , 3 , 3 , 4 , 4 , 4 , 4 ,
+  5 , 5 , 5 , 6 , 6 , 6 , 7 , 7 , 7 , 7 , 8 , 8 , 8 , 9 , 9 , 9 ,
+  10, 10, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14,
+  14, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19,
+  19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 24,
+  24, 24, 25, 25, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 28, 28,
+  29, 29, 29, 30, 30, 30, 30, 31, 31, 31, 32, 32, 32, 33, 33, 33,
+  33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 36, 37, 37, 37, 38, 38,
+  38, 39, 39, 39, 39, 40, 40, 40, 41, 41, 41, 42, 42, 42, 42, 43,
+  43, 43, 44, 44, 44, 45, 45, 45, 45, 46, 46, 46, 47, 47, 47, 48,
+  48, 48, 48, 49, 49, 49, 50, 50, 50, 51, 51, 51, 51, 52, 52, 52,
+  53, 53, 53, 54, 54, 54, 54, 55, 55, 55, 56, 56, 56, 57, 57, 57,
+  57, 58, 58, 58, 59, 59, 59, 60, 60, 60, 60, 61, 61, 61, 62, 62,
+  62, 62, 63, 63, 63, 64, 64, 64, 65, 65, 65, 65, 66, 66, 66, 67,
+  67, 67, 68, 68, 68, 68, 69, 69, 69, 70, 70, 70, 71, 71, 71, 71,
+  72, 72, 72, 73, 73, 73, 74, 74, 74, 74, 75, 75, 75, 76, 76, 76
+};
+
+const unsigned char green_lut[256] = {
+  0  , 1  , 1  , 2  , 2  , 3  , 4  , 4  , 5  , 5  , 6  , 6  ,
+  7  , 8  , 8  , 9  , 9  , 10 , 11 , 11 , 12 , 12 , 13 , 14 ,
+  14 , 15 , 15 , 16 , 16 , 17 , 18 , 18 , 19 , 19 , 20 , 21 ,
+  21 , 22 , 22 , 23 , 23 , 24 , 25 , 25 , 26 , 26 , 27 , 28 ,
+  28 , 29 , 29 , 30 , 31 , 31 , 32 , 32 , 33 , 33 , 34 , 35 ,
+  35 , 36 , 36 , 37 , 38 , 38 , 39 , 39 , 40 , 41 , 41 , 42 ,
+  42 , 43 , 43 , 44 , 45 , 45 , 46 , 46 , 47 , 48 , 48 , 49 ,
+  49 , 50 , 50 , 51 , 52 , 52 , 53 , 53 , 54 , 55 , 55 , 56 ,
+  56 , 57 , 58 , 58 , 59 , 59 , 60 , 60 , 61 , 62 , 62 , 63 ,
+  63 , 64 , 65 , 65 , 66 , 66 , 67 , 68 , 68 , 69 , 69 , 70 ,
+  70 , 71 , 72 , 72 , 73 , 73 , 74 , 75 , 75 , 76 , 76 , 77 ,
+  77 , 78 , 79 , 79 , 80 , 80 , 81 , 82 , 82 , 83 , 83 , 84 ,
+  85 , 85 , 86 , 86 , 87 , 87 , 88 , 89 , 89 , 90 , 90 , 91 ,
+  92 , 92 , 93 , 93 , 94 , 95 , 95 , 96 , 96 , 97 , 97 , 98 ,
+  99 , 99 , 100, 100, 101, 102, 102, 103, 103, 104, 104, 105,
+  106, 106, 107, 107, 108, 109, 109, 110, 110, 111, 112, 112,
+  113, 113, 114, 114, 115, 116, 116, 117, 117, 118, 119, 119,
+  120, 120, 121, 122, 122, 123, 123, 124, 124, 125, 126, 126,
+  127, 127, 128, 129, 129, 130, 130, 131, 131, 132, 133, 133,
+  34, 134, 135, 136, 136, 137, 137, 138, 139, 139, 140, 140,
+  141, 141, 142, 143, 143, 144, 144, 145, 146, 146, 147, 147,
+  148, 149, 149, 150
+};
+
+const unsigned char blue_lut[256] = {
+  0 , 0 , 0 , 0 , 0 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 2 , 2 ,
+  2 , 2 , 2 , 2 , 2 , 2 , 3 , 3 , 3 , 3 , 3 , 3 , 3 , 3 , 3 , 4 ,
+  4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 ,
+  5 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 7 , 7 , 7 , 7 , 7 , 7 ,
+  7 , 7 , 8 , 8 , 8 , 8 , 8 , 8 , 8 , 8 , 8 , 9 , 9 , 9 , 9 , 9 ,
+  9 , 9 , 9 , 9 , 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11,
+  11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13,
+  13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+  15, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
+  16, 17, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18,
+  18, 18, 18, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20, 20,
+  20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22,
+  22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 23, 23, 23, 24,
+  24, 24, 24, 24, 24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+  26, 26, 26, 26, 26, 26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27,
+  27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 29, 29, 29, 29
+};
+
+#endif
+
+
 /*
  * Initialize for RGB->YCC colorspace conversion.
  */
@@ -191,26 +259,36 @@ rgb_gray_convert (j_compress_ptr cinfo,
 		  JDIMENSION output_row, int num_rows)
 {
   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
-  register int r, g, b;
+  #if BITS_IN_JSAMPLE != 8
   register INT32 * ctab = cconvert->rgb_ycc_tab;
+  #endif
   register JSAMPROW inptr;
   register JSAMPROW outptr;
+  JSAMPLE *maxoutptr;
   register JDIMENSION col;
   JDIMENSION num_cols = cinfo->image_width;
+  int rindex = rgb_red[cinfo->in_color_space];
+  int gindex = rgb_green[cinfo->in_color_space];
+  int bindex = rgb_blue[cinfo->in_color_space];
+  int rgbstride = rgb_pixelsize[cinfo->in_color_space];
 
   while (--num_rows >= 0) {
     inptr = *input_buf++;
     outptr = output_buf[0][output_row];
+    maxoutptr = &outptr[num_cols];
     output_row++;
-    for (col = 0; col < num_cols; col++) {
-      r = GETJSAMPLE(inptr[rgb_red[cinfo->in_color_space]]);
-      g = GETJSAMPLE(inptr[rgb_green[cinfo->in_color_space]]);
-      b = GETJSAMPLE(inptr[rgb_blue[cinfo->in_color_space]]);
-      inptr += rgb_pixelsize[cinfo->in_color_space];
+    for (; outptr < maxoutptr; outptr++, inptr += rgbstride) {
       /* Y */
-      outptr[col] = (JSAMPLE)
-		((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
-		 >> SCALEBITS);
+      #if BITS_IN_JSAMPLE == 8
+      *outptr = red_lut[inptr[rindex]] + green_lut[inptr[gindex]]
+	    + blue_lut[inptr[bindex]];
+      #else
+      *outptr = (JSAMPLE)
+	    ((ctab[GETJSAMPLE(inptr[rindex])+R_Y_OFF]
+	     + ctab[GETJSAMPLE(inptr[gindex])+G_Y_OFF]
+	     + ctab[GETJSAMPLE(inptr[bindex])+B_Y_OFF])
+	     >> SCALEBITS);
+      #endif
     }
   }
 }