Create Subversion repository

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@1 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 123 insertions, 0 deletions

diff --git a/lib/lum.h b/lib/lum.h
new file mode 100644
index 00000000..34d3866e
--- /dev/null
+++ b/lib/lum.h
@@ -0,0 +1,123 @@
+    /* Lookup tables for fast RGB -> luminance calculation. */
+    static int times77[256] = {
+	    0,    77,   154,   231,   308,   385,   462,   539,
+	  616,   693,   770,   847,   924,  1001,  1078,  1155,
+	 1232,  1309,  1386,  1463,  1540,  1617,  1694,  1771,
+	 1848,  1925,  2002,  2079,  2156,  2233,  2310,  2387,
+	 2464,  2541,  2618,  2695,  2772,  2849,  2926,  3003,
+	 3080,  3157,  3234,  3311,  3388,  3465,  3542,  3619,
+	 3696,  3773,  3850,  3927,  4004,  4081,  4158,  4235,
+	 4312,  4389,  4466,  4543,  4620,  4697,  4774,  4851,
+	 4928,  5005,  5082,  5159,  5236,  5313,  5390,  5467,
+	 5544,  5621,  5698,  5775,  5852,  5929,  6006,  6083,
+	 6160,  6237,  6314,  6391,  6468,  6545,  6622,  6699,
+	 6776,  6853,  6930,  7007,  7084,  7161,  7238,  7315,
+	 7392,  7469,  7546,  7623,  7700,  7777,  7854,  7931,
+	 8008,  8085,  8162,  8239,  8316,  8393,  8470,  8547,
+	 8624,  8701,  8778,  8855,  8932,  9009,  9086,  9163,
+	 9240,  9317,  9394,  9471,  9548,  9625,  9702,  9779,
+	 9856,  9933, 10010, 10087, 10164, 10241, 10318, 10395,
+	10472, 10549, 10626, 10703, 10780, 10857, 10934, 11011,
+	11088, 11165, 11242, 11319, 11396, 11473, 11550, 11627,
+	11704, 11781, 11858, 11935, 12012, 12089, 12166, 12243,
+	12320, 12397, 12474, 12551, 12628, 12705, 12782, 12859,
+	12936, 13013, 13090, 13167, 13244, 13321, 13398, 13475,
+	13552, 13629, 13706, 13783, 13860, 13937, 14014, 14091,
+	14168, 14245, 14322, 14399, 14476, 14553, 14630, 14707,
+	14784, 14861, 14938, 15015, 15092, 15169, 15246, 15323,
+	15400, 15477, 15554, 15631, 15708, 15785, 15862, 15939,
+	16016, 16093, 16170, 16247, 16324, 16401, 16478, 16555,
+	16632, 16709, 16786, 16863, 16940, 17017, 17094, 17171,
+	17248, 17325, 17402, 17479, 17556, 17633, 17710, 17787,
+	17864, 17941, 18018, 18095, 18172, 18249, 18326, 18403,
+	18480, 18557, 18634, 18711, 18788, 18865, 18942, 19019,
+	19096, 19173, 19250, 19327, 19404, 19481, 19558, 19635 };
+    static int times150[256] = {
+	    0,   150,   300,   450,   600,   750,   900,  1050,
+	 1200,  1350,  1500,  1650,  1800,  1950,  2100,  2250,
+	 2400,  2550,  2700,  2850,  3000,  3150,  3300,  3450,
+	 3600,  3750,  3900,  4050,  4200,  4350,  4500,  4650,
+	 4800,  4950,  5100,  5250,  5400,  5550,  5700,  5850,
+	 6000,  6150,  6300,  6450,  6600,  6750,  6900,  7050,
+	 7200,  7350,  7500,  7650,  7800,  7950,  8100,  8250,
+	 8400,  8550,  8700,  8850,  9000,  9150,  9300,  9450,
+	 9600,  9750,  9900, 10050, 10200, 10350, 10500, 10650,
+	10800, 10950, 11100, 11250, 11400, 11550, 11700, 11850,
+	12000, 12150, 12300, 12450, 12600, 12750, 12900, 13050,
+	13200, 13350, 13500, 13650, 13800, 13950, 14100, 14250,
+	14400, 14550, 14700, 14850, 15000, 15150, 15300, 15450,
+	15600, 15750, 15900, 16050, 16200, 16350, 16500, 16650,
+	16800, 16950, 17100, 17250, 17400, 17550, 17700, 17850,
+	18000, 18150, 18300, 18450, 18600, 18750, 18900, 19050,
+	19200, 19350, 19500, 19650, 19800, 19950, 20100, 20250,
+	20400, 20550, 20700, 20850, 21000, 21150, 21300, 21450,
+	21600, 21750, 21900, 22050, 22200, 22350, 22500, 22650,
+	22800, 22950, 23100, 23250, 23400, 23550, 23700, 23850,
+	24000, 24150, 24300, 24450, 24600, 24750, 24900, 25050,
+	25200, 25350, 25500, 25650, 25800, 25950, 26100, 26250,
+	26400, 26550, 26700, 26850, 27000, 27150, 27300, 27450,
+	27600, 27750, 27900, 28050, 28200, 28350, 28500, 28650,
+	28800, 28950, 29100, 29250, 29400, 29550, 29700, 29850,
+	30000, 30150, 30300, 30450, 30600, 30750, 30900, 31050,
+	31200, 31350, 31500, 31650, 31800, 31950, 32100, 32250,
+	32400, 32550, 32700, 32850, 33000, 33150, 33300, 33450,
+	33600, 33750, 33900, 34050, 34200, 34350, 34500, 34650,
+	34800, 34950, 35100, 35250, 35400, 35550, 35700, 35850,
+	36000, 36150, 36300, 36450, 36600, 36750, 36900, 37050,
+	37200, 37350, 37500, 37650, 37800, 37950, 38100, 38250 };
+    static int times29[256] = {
+	    0,    29,    58,    87,   116,   145,   174,   203,
+	  232,   261,   290,   319,   348,   377,   406,   435,
+	  464,   493,   522,   551,   580,   609,   638,   667,
+	  696,   725,   754,   783,   812,   841,   870,   899,
+	  928,   957,   986,  1015,  1044,  1073,  1102,  1131,
+	 1160,  1189,  1218,  1247,  1276,  1305,  1334,  1363,
+	 1392,  1421,  1450,  1479,  1508,  1537,  1566,  1595,
+	 1624,  1653,  1682,  1711,  1740,  1769,  1798,  1827,
+	 1856,  1885,  1914,  1943,  1972,  2001,  2030,  2059,
+	 2088,  2117,  2146,  2175,  2204,  2233,  2262,  2291,
+	 2320,  2349,  2378,  2407,  2436,  2465,  2494,  2523,
+	 2552,  2581,  2610,  2639,  2668,  2697,  2726,  2755,
+	 2784,  2813,  2842,  2871,  2900,  2929,  2958,  2987,
+	 3016,  3045,  3074,  3103,  3132,  3161,  3190,  3219,
+	 3248,  3277,  3306,  3335,  3364,  3393,  3422,  3451,
+	 3480,  3509,  3538,  3567,  3596,  3625,  3654,  3683,
+	 3712,  3741,  3770,  3799,  3828,  3857,  3886,  3915,
+	 3944,  3973,  4002,  4031,  4060,  4089,  4118,  4147,
+	 4176,  4205,  4234,  4263,  4292,  4321,  4350,  4379,
+	 4408,  4437,  4466,  4495,  4524,  4553,  4582,  4611,
+	 4640,  4669,  4698,  4727,  4756,  4785,  4814,  4843,
+	 4872,  4901,  4930,  4959,  4988,  5017,  5046,  5075,
+	 5104,  5133,  5162,  5191,  5220,  5249,  5278,  5307,
+	 5336,  5365,  5394,  5423,  5452,  5481,  5510,  5539,
+	 5568,  5597,  5626,  5655,  5684,  5713,  5742,  5771,
+	 5800,  5829,  5858,  5887,  5916,  5945,  5974,  6003,
+	 6032,  6061,  6090,  6119,  6148,  6177,  6206,  6235,
+	 6264,  6293,  6322,  6351,  6380,  6409,  6438,  6467,
+	 6496,  6525,  6554,  6583,  6612,  6641,  6670,  6699,
+	 6728,  6757,  6786,  6815,  6844,  6873,  6902,  6931,
+	 6960,  6989,  7018,  7047,  7076,  7105,  7134,  7163,
+	 7192,  7221,  7250,  7279,  7308,  7337,  7366,  7395 };
+
+/* The ppm_fastlumin() macro is a way to compute luminosity without
+   floating point arithmetic.  On modern computers, floating point often isn't
+   any slower, so you may prefer ppm_lumin() in ppm.h.
+
+   ppm_fastlumin() works only with maxval <= 255, because the multiplication
+   tables go up only that high.
+
+   In the following arithmetic, note that shifting right 8 bits is the same
+   as dividing by (77+150+29), but some compilers may generate faster code
+   for >>8 than for /(77+150+29).
+*/
+static __inline__ pixval
+ppm_fastlumin(pixel const p) {
+
+    return
+        (times77[PPM_GETR(p)] +
+         times150[PPM_GETG(p)] +
+         times29[PPM_GETB(p)] +
+         128)  /* round off */
+             >> 8;
+}
+