[4/4] Ordered dithering with blue noise

Submitted by basile-pixman@clement.pm on April 9, 2019, 9:29 p.m.

Details

Message ID 20190409212927.12731-5-basile-pixman@clement.pm
State New
Headers show
Series "Series without cover letter" ( rev: 2 1 ) in Pixman

Not browsing as part of any series.

Commit Message

basile-pixman@clement.pm April 9, 2019, 9:29 p.m.
From: Basile Clement <basile-pixman@clement.pm>

On some screens (typically low quality laptop screens), using Bayer
ordered dithering has been observed to cause color changes depending on
*where the gradient is rendered on the screen*, causing visible
flickering when moving an image on the screen.

To alleviate the issue, this patch adds support for ordered dithering
using a 64x64 matrix tuned from blue noise.  In addition to being devoid
of the positional dependency on screen, the blue noise matrix also
generates more pleasing and less discernable patterns.  As such, it is
now the method used for PIXMAN_DITHER_GOOD and PIXMAN_DITHER_BEST
dithering methods.

The 64x64 blue noise matrix has been generated using the provided
`pixman/dither/make-blue-noise.c` script, which uses the
void-and-cluster method.
---
 demos/dither.c                   |   1 +
 pixman/dither/blue-noise-64x64.h |  77 ++++
 pixman/dither/make-blue-noise.c  | 679 +++++++++++++++++++++++++++++++
 pixman/pixman-bits-image.c       |  16 +-
 pixman/pixman.h                  |   1 +
 test/tolerance-test.c            |   1 +
 test/utils.c                     |   1 +
 7 files changed, 775 insertions(+), 1 deletion(-)
 create mode 100644 pixman/dither/blue-noise-64x64.h
 create mode 100644 pixman/dither/make-blue-noise.c

Patch hide | download patch | download mbox

diff --git a/demos/dither.c b/demos/dither.c
index d4271e6..d72c250 100644
--- a/demos/dither.c
+++ b/demos/dither.c
@@ -78,6 +78,7 @@  static const named_int_t dithers[] =
 {
     { "None",                   PIXMAN_REPEAT_NONE },
     { "Bayer 8x8",              PIXMAN_DITHER_ORDERED_BAYER_8 },
+    { "Blue noise 64x64",       PIXMAN_DITHER_ORDERED_BLUE_NOISE_64 },
 };
 
 static int
diff --git a/pixman/dither/blue-noise-64x64.h b/pixman/dither/blue-noise-64x64.h
new file mode 100644
index 0000000..e196d2d
--- /dev/null
+++ b/pixman/dither/blue-noise-64x64.h
@@ -0,0 +1,77 @@ 
+/* WARNING: This file is generated by make-blue-noise.c
+ * Please edit that file instead of this one.
+ */
+
+#ifndef BLUE_NOISE_64X64_H
+#define BLUE_NOISE_64X64_H
+
+#include <stdint.h>
+
+static const uint32_t dither_blue_noise_64x64[4096] = {
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+    2822, 3391, 745, 3813, 192, 1274, 2941, 3847, 2489, 3440, 744, 161, 1422, 1086, 572, 3004, 2617, 338, 3807, 2031, 236, 2472, 3065, 2098, 3358, 362, 2163, 3574, 497, 2788, 1970, 948, 3885, 685, 3100, 1712, 2228, 292, 1408, 1016, 164, 3537, 1417, 941, 34, 2172, 3001, 358, 1491, 3147, 699, 3356, 258, 1149, 2946, 1787, 3931, 382, 1146, 3291, 818, 2890, 2379, 1096,
+    3679, 1328, 1901, 3162, 2747, 1730, 2253, 5, 1556, 2818, 2093, 3166, 2522, 3410, 2287, 1701, 956, 3237, 620, 1596, 3300, 1307, 511, 3701, 1020, 2939, 1362, 2532, 3208, 749, 3641, 160, 1522, 2624, 1095, 4086, 826, 2841, 3583, 2173, 1727, 723, 2925, 1911, 2482, 3726, 863, 1962, 4028, 1111, 2835, 3773, 2449, 2022, 582, 3278, 923, 2619, 2152, 4039, 92, 1934, 3145, 677,
+    2530, 53, 2303, 1003, 458, 3989, 739, 3321, 1064, 369, 3556, 877, 1900, 426, 3876, 1, 3617, 2106, 1197, 2805, 3634, 857, 2706, 1504, 2418, 682, 3868, 20, 1139, 1688, 2333, 3311, 2907, 1945, 265, 2385, 3433, 1601, 636, 2620, 3095, 4044, 386, 3382, 1184, 527, 2814, 3414, 2342, 465, 1889, 1343, 874, 3479, 1502, 2233, 3689, 1385, 559, 2745, 1463, 3465, 376, 1718,
+    3217, 4045, 1580, 3612, 2525, 1228, 3018, 1958, 3725, 2358, 1361, 3996, 1581, 3063, 1224, 2737, 1475, 2442, 3946, 191, 1796, 2128, 3975, 134, 1916, 3318, 1597, 2071, 3749, 2672, 403, 1278, 602, 3745, 3220, 1374, 445, 2064, 3830, 243, 1252, 2390, 1563, 2724, 3875, 1818, 1346, 165, 1650, 3264, 2680, 117, 2998, 4081, 343, 2799, 9, 3122, 1743, 3724, 1040, 2231, 3842, 1209,
+    900, 398, 2851, 697, 1797, 3482, 293, 2679, 1649, 566, 2954, 91, 2697, 714, 2060, 3211, 781, 480, 3040, 1038, 2611, 666, 2989, 3458, 1201, 2796, 548, 2975, 839, 3121, 1850, 4001, 2208, 1631, 790, 2558, 2972, 1148, 3213, 1849, 3624, 971, 2102, 108, 772, 3101, 2589, 3777, 1042, 656, 3907, 2097, 1615, 2540, 805, 1935, 1231, 3494, 2451, 268, 2995, 750, 2682, 2020,
+    3024, 1392, 2124, 3279, 106, 2217, 1387, 822, 3214, 3825, 2160, 1000, 2395, 3691, 228, 4038, 1872, 3413, 1608, 2225, 3536, 303, 1653, 886, 2541, 224, 4037, 2252, 1428, 172, 3504, 958, 2848, 113, 3628, 1834, 3979, 19, 2317, 779, 2797, 518, 3174, 3549, 1482, 2266, 444, 2014, 3555, 2439, 1213, 3113, 535, 1135, 3204, 3858, 2309, 931, 623, 2009, 3359, 1566, 140, 3550,
+    1808, 3872, 2488, 1152, 3764, 2892, 3960, 2412, 353, 1223, 1825, 3444, 3116, 1717, 1082, 2313, 1280, 2661, 82, 3852, 1389, 3200, 2330, 3812, 2038, 3581, 1728, 1039, 3339, 2427, 586, 2580, 1238, 3328, 2280, 1047, 595, 2662, 1363, 3338, 1620, 3934, 2497, 1881, 1054, 3954, 3215, 864, 2887, 1801, 320, 3519, 2378, 3704, 1753, 424, 2958, 1660, 4005, 2601, 1116, 3912, 2381, 573,
+    2740, 200, 828, 1667, 432, 1931, 1035, 1616, 3598, 2640, 728, 264, 1437, 557, 3501, 2966, 372, 3734, 974, 1978, 758, 2719, 1145, 452, 1433, 725, 2681, 408, 3843, 1918, 1547, 3906, 1996, 503, 1456, 3019, 3493, 1700, 3742, 355, 2134, 176, 1311, 615, 2867, 315, 1680, 1314, 8, 3297, 1494, 783, 1950, 83, 2656, 1382, 3561, 138, 2834, 1404, 330, 1904, 3156, 1027,
+    1357, 3381, 3041, 3666, 2729, 734, 3415, 177, 3051, 2021, 4079, 2823, 3775, 2186, 2616, 869, 1668, 3148, 2367, 3315, 393, 4075, 1870, 2920, 3343, 2362, 3188, 1303, 2782, 825, 3171, 259, 2905, 3717, 2538, 184, 2074, 838, 2860, 2407, 1024, 3496, 3008, 3706, 1985, 2349, 3623, 2582, 4058, 2184, 2694, 3873, 2964, 990, 3346, 690, 2033, 1066, 2201, 3490, 2971, 718, 3700, 2188,
+    4061, 391, 1989, 2325, 1430, 3150, 2125, 2526, 592, 1403, 976, 2351, 1165, 1851, 114, 3921, 2063, 613, 1358, 2785, 1623, 2254, 25, 3542, 1045, 246, 1852, 3554, 87, 2243, 3615, 1169, 727, 1705, 968, 3957, 3185, 1251, 500, 4063, 1751, 2622, 842, 1519, 90, 3393, 819, 490, 1874, 999, 571, 1275, 2271, 1586, 4040, 2448, 3126, 3731, 436, 885, 1708, 2421, 24, 1599,
+    889, 2563, 1199, 645, 70, 4013, 1237, 3723, 1694, 3499, 3, 3266, 484, 2997, 3390, 1233, 2842, 3687, 152, 3480, 1084, 3698, 881, 2490, 1542, 3992, 2209, 692, 1690, 3022, 1470, 2625, 2114, 3512, 2359, 381, 2684, 1897, 3368, 1395, 3080, 289, 2065, 3981, 2758, 1141, 3097, 1472, 2870, 3352, 3707, 225, 3159, 505, 1895, 214, 1222, 1774, 2686, 3978, 3275, 1196, 3518, 2825,
+    3270, 1720, 3796, 3466, 2650, 1841, 298, 899, 2862, 2091, 2671, 1744, 3735, 801, 1560, 349, 2262, 903, 1833, 2524, 512, 3117, 1793, 2827, 476, 3038, 1216, 2550, 3826, 980, 431, 4048, 35, 2992, 1265, 1595, 765, 3675, 76, 2247, 696, 3456, 1254, 2452, 664, 1757, 2133, 3750, 145, 2332, 1554, 1981, 3580, 2712, 868, 3640, 2919, 638, 2275, 1427, 309, 2595, 2006, 492,
+    2226, 178, 2911, 836, 1528, 3028, 2240, 3327, 404, 3970, 707, 1294, 2464, 2131, 4032, 2600, 3319, 1406, 2913, 3974, 2156, 1425, 221, 3877, 2017, 811, 3662, 272, 3287, 1988, 2408, 3357, 1746, 598, 3239, 3823, 2182, 2934, 1078, 2604, 3840, 1697, 2906, 413, 3210, 3880, 331, 2644, 1260, 848, 3042, 2535, 1077, 1438, 3261, 2365, 1561, 3799, 85, 3082, 1876, 674, 3932, 1101,
+    3644, 1344, 1943, 2401, 390, 3835, 1048, 2572, 1541, 1133, 3075, 3584, 308, 2889, 1065, 1869, 601, 3783, 282, 1181, 736, 3312, 2368, 1126, 3383, 1675, 2734, 1426, 628, 2873, 1317, 843, 2717, 2048, 1004, 2536, 333, 1782, 3295, 1517, 219, 2153, 815, 3502, 1579, 2268, 987, 3409, 1780, 4018, 354, 665, 3914, 47, 1956, 456, 1006, 2010, 3406, 1130, 3621, 2894, 1549, 3092,
+    2485, 640, 3993, 3179, 1270, 3436, 585, 1925, 3757, 2304, 136, 1976, 1486, 646, 3520, 50, 3155, 1637, 2435, 3522, 1937, 2756, 3748, 661, 2224, 58, 3230, 2357, 1830, 3892, 170, 3607, 1447, 3949, 190, 3392, 1336, 584, 4010, 918, 3016, 3670, 1155, 2406, 52, 1304, 3009, 607, 2085, 2699, 3205, 1848, 2291, 3402, 2764, 3865, 3048, 2508, 735, 2710, 443, 2341, 897, 263,
+    1785, 2769, 983, 56, 2197, 1685, 2703, 202, 2944, 810, 3377, 2626, 3787, 3047, 2055, 1236, 2752, 2122, 945, 3093, 96, 1624, 439, 3014, 1388, 4015, 977, 448, 3506, 1098, 2242, 3026, 506, 2361, 2952, 1862, 3619, 2790, 1992, 2483, 525, 1868, 2652, 4093, 1998, 3595, 2478, 3816, 122, 1412, 929, 3716, 1166, 1648, 813, 1300, 199, 1489, 3998, 1771, 1310, 3808, 2052, 3423,
+    434, 3712, 1625, 3558, 2955, 853, 4019, 1348, 3511, 1732, 1246, 487, 934, 1672, 2510, 3965, 788, 3711, 396, 1369, 4090, 1055, 2603, 1879, 3528, 2518, 2067, 3005, 1516, 2588, 751, 1740, 3418, 1131, 1576, 686, 2296, 1118, 18, 3263, 1365, 3401, 294, 737, 3177, 410, 867, 1633, 2963, 3579, 2375, 252, 2881, 479, 2471, 3576, 2180, 3306, 332, 2255, 3035, 41, 2648, 1396,
+    2929, 2230, 1219, 2512, 446, 2008, 3189, 2388, 626, 2164, 2831, 4047, 2376, 174, 3272, 368, 1469, 3226, 2578, 1991, 2874, 2263, 3681, 876, 188, 1239, 683, 3776, 226, 3183, 4083, 2148, 63, 2649, 3859, 299, 3086, 3933, 1585, 2185, 3767, 988, 1707, 2908, 1407, 1844, 2771, 2245, 1161, 560, 1755, 3376, 2051, 4064, 3135, 1832, 652, 2853, 1051, 3649, 760, 3290, 1105, 3945,
+    872, 154, 3207, 713, 3780, 1453, 281, 1087, 3695, 30, 3299, 1919, 1400, 3551, 1119, 1890, 2314, 618, 1703, 3428, 724, 295, 3146, 1557, 3341, 2896, 1683, 2723, 1974, 1017, 541, 1380, 3720, 804, 3280, 2082, 997, 2567, 777, 2961, 213, 2707, 2328, 3632, 1025, 3891, 3304, 255, 4003, 3108, 2587, 1323, 743, 1479, 105, 1013, 3901, 1618, 2044, 2627, 1465, 1846, 576, 1994,
+    2560, 3521, 1742, 2118, 2800, 3404, 1783, 2609, 2968, 1582, 1022, 412, 2713, 687, 2976, 3857, 2761, 3620, 62, 1108, 3844, 1340, 2100, 540, 2345, 3925, 405, 3457, 1319, 2468, 3362, 2815, 1867, 2372, 1281, 1714, 3690, 482, 3498, 1842, 1285, 3994, 558, 2039, 81, 2499, 678, 1481, 1923, 964, 12, 3824, 2980, 2205, 2762, 3432, 2398, 181, 3247, 462, 4094, 2350, 3589, 3089,
+    1555, 1094, 4041, 247, 1267, 908, 3959, 2041, 732, 3860, 2343, 3132, 3769, 2144, 1621, 237, 912, 1329, 3025, 2146, 2642, 1775, 3721, 2746, 1121, 1953, 902, 2285, 130, 3671, 1659, 278, 3153, 522, 2721, 123, 2996, 1466, 2380, 377, 3231, 873, 1510, 3476, 3123, 1250, 2147, 3650, 2839, 3451, 2323, 1122, 3545, 379, 1765, 1218, 603, 3768, 1360, 938, 2885, 133, 1245, 363,
+    2364, 554, 2743, 3344, 2474, 530, 3112, 169, 1297, 3430, 536, 1741, 98, 1043, 2574, 3253, 2246, 1854, 4022, 510, 3283, 204, 858, 3398, 36, 3118, 1478, 3794, 2986, 706, 2176, 922, 3559, 1097, 3976, 3322, 2149, 1160, 2810, 3883, 2007, 2513, 2953, 328, 1721, 3793, 422, 2566, 807, 329, 1638, 1967, 648, 2520, 3727, 3109, 2116, 2927, 2491, 1939, 3365, 1709, 2728, 3815,
+    2037, 3120, 831, 1405, 1896, 3592, 1622, 2369, 2864, 2151, 1107, 2542, 3532, 1410, 3917, 427, 3568, 709, 2509, 1503, 1037, 2973, 2436, 1604, 4035, 2594, 563, 1819, 2659, 1234, 4004, 2565, 1511, 2273, 1823, 336, 882, 3772, 575, 1628, 171, 3570, 1120, 2260, 2716, 935, 3064, 1806, 1342, 3144, 3900, 2744, 3296, 985, 1546, 238, 896, 1663, 305, 3660, 695, 2213, 960, 3407,
+    144, 1795, 3894, 2267, 51, 2708, 1023, 3818, 366, 1821, 4087, 2985, 755, 2057, 2912, 949, 1583, 2774, 231, 3447, 2258, 3866, 1982, 672, 1225, 2077, 3320, 1062, 370, 3241, 1968, 7, 3068, 681, 3631, 2573, 1567, 3175, 2321, 1067, 3070, 722, 1856, 3744, 642, 1471, 4084, 131, 3514, 2443, 531, 1227, 155, 2265, 4024, 2658, 3326, 3910, 1168, 3078, 1530, 3956, 489, 1424,
+    3647, 1203, 420, 2924, 3755, 719, 3248, 1376, 3067, 890, 196, 1559, 3269, 270, 2432, 1885, 3212, 1164, 3778, 1752, 579, 1338, 344, 3585, 3017, 288, 3658, 2371, 3882, 1691, 611, 2789, 3809, 1339, 389, 2950, 2015, 59, 3548, 2751, 2158, 4011, 1352, 29, 3388, 2370, 2812, 1946, 954, 2110, 1558, 2947, 3573, 1909, 1326, 679, 1853, 2312, 551, 2702, 33, 2414, 3209, 2824,
+    2547, 2143, 3379, 966, 1492, 1979, 2479, 463, 2194, 3657, 2738, 2318, 1261, 3713, 604, 4002, 11, 2192, 2967, 919, 2607, 3369, 2837, 1676, 2539, 984, 1568, 93, 2901, 1318, 3538, 1041, 2216, 1756, 3454, 1030, 4050, 1402, 798, 1723, 311, 3277, 2546, 2886, 2043, 461, 1206, 3677, 361, 3260, 3988, 809, 2605, 470, 3007, 3517, 102, 3221, 1398, 2062, 3611, 1134, 1928, 865,
+    4060, 621, 1710, 2606, 3510, 317, 4017, 1682, 3329, 1159, 1940, 654, 3461, 1789, 1015, 2691, 1455, 3599, 374, 1947, 4069, 71, 2126, 763, 3961, 2278, 3161, 1997, 824, 2623, 2080, 244, 3257, 780, 2732, 2308, 545, 3351, 2476, 3806, 1204, 588, 1591, 963, 3610, 1699, 754, 3049, 2651, 1106, 65, 2221, 1644, 3821, 1100, 2463, 1614, 3801, 965, 2965, 715, 3394, 1593, 212,
+};
+
+#endif /* BLUE_NOISE_64X64_H */
diff --git a/pixman/dither/make-blue-noise.c b/pixman/dither/make-blue-noise.c
new file mode 100644
index 0000000..45e48a6
--- /dev/null
+++ b/pixman/dither/make-blue-noise.c
@@ -0,0 +1,679 @@ 
+/* Blue noise generation using the void-and-cluster method as described in
+ *
+ *     The void-and-cluster method for dither array generation
+ *     Ulichney, Robert A (1993)
+ *
+ *     http://cv.ulichney.com/papers/1993-void-cluster.pdf
+ *
+ * Note that running with openmp (-DUSE_OPENMP) will trigger additional
+ * randomness due to computing reductions in parallel, and is not recommended
+ * unless generating very large dither arrays.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <math.h>
+#include <stdio.h>
+
+/* Booleans and utility functions */
+
+#ifndef TRUE
+#   define TRUE 1
+#endif
+
+#ifndef FALSE
+#   define FALSE 0
+#endif
+
+typedef int bool_t;
+
+int
+imin (int x, int y)
+{
+    return x < y ? x : y;
+}
+
+/* Memory allocation */
+void *
+malloc_abc (unsigned int a, unsigned int b, unsigned int c)
+{
+    if (a >= INT32_MAX / b)
+	return NULL;
+    else if (a * b >= INT32_MAX / c)
+	return NULL;
+    else
+	return malloc (a * b * c);
+}
+
+/* Random number generation */
+typedef uint32_t xorwow_state_t[5];
+
+uint32_t
+xorwow_next (xorwow_state_t *state)
+{
+    uint32_t s = (*state)[0],
+    t = (*state)[3];
+    (*state)[3] = (*state)[2];
+    (*state)[2] = (*state)[1];
+    (*state)[1] = s;
+
+    t ^= t >> 2;
+    t ^= t << 1;
+    t ^= s ^ (s << 4);
+
+    (*state)[0] = t;
+    (*state)[4] += 362437;
+
+    return t + (*state)[4];
+}
+
+float
+xorwow_float (xorwow_state_t *s)
+{
+    return (xorwow_next (s) >> 9) / (float)((1 << 23) - 1);
+}
+
+/* Floating point matrices
+ *
+ * Used to cache the cluster sizes.
+ */
+typedef struct matrix_t {
+    int width;
+    int height;
+    float *buffer;
+} matrix_t;
+
+bool_t
+matrix_init (matrix_t *matrix, int width, int height)
+{
+    float *buffer;
+
+    if (!matrix)
+	return FALSE;
+
+    buffer = malloc_abc (width, height, sizeof (float));
+
+    if (!buffer)
+	return FALSE;
+
+    matrix->buffer = buffer;
+    matrix->width  = width;
+    matrix->height = height;
+
+    return TRUE;
+}
+
+bool_t
+matrix_copy (matrix_t *dst, matrix_t const *src)
+{
+    float *srcbuf = src->buffer,
+	  *srcend = src->buffer + src->width * src->height,
+	  *dstbuf = dst->buffer;
+
+    if (dst->width != src->width || dst->height != src->height)
+	return FALSE;
+
+    while (srcbuf < srcend)
+	*dstbuf++ = *srcbuf++;
+
+    return TRUE;
+}
+
+float *
+matrix_get (matrix_t *matrix, int x, int y)
+{
+    return &matrix->buffer[y * matrix->width + x];
+}
+
+void
+matrix_destroy (matrix_t *matrix)
+{
+    free (matrix->buffer);
+}
+
+/* Binary patterns */
+typedef struct pattern_t {
+    int width;
+    int height;
+    bool_t *buffer;
+} pattern_t;
+
+bool_t
+pattern_init (pattern_t *pattern, int width, int height)
+{
+    bool_t *buffer;
+
+    if (!pattern)
+	return FALSE;
+
+    buffer = malloc_abc (width, height, sizeof (bool_t));
+
+    if (!buffer)
+	return FALSE;
+
+    pattern->buffer = buffer;
+    pattern->width  = width;
+    pattern->height = height;
+
+    return TRUE;
+}
+
+bool_t
+pattern_copy (pattern_t *dst, pattern_t const *src)
+{
+    bool_t *srcbuf = src->buffer,
+	   *srcend = src->buffer + src->width * src->height,
+	   *dstbuf = dst->buffer;
+
+    if (dst->width != src->width || dst->height != src->height)
+	return FALSE;
+
+    while (srcbuf < srcend)
+	*dstbuf++ = *srcbuf++;
+
+    return TRUE;
+}
+
+bool_t *
+pattern_get (pattern_t *pattern, int x, int y)
+{
+    return &pattern->buffer[y * pattern->width + x];
+}
+
+void
+pattern_fill_white_noise (pattern_t *pattern, float fraction,
+			  xorwow_state_t *s)
+{
+    bool_t *buffer = pattern->buffer;
+    bool_t *end    = buffer + (pattern->width * pattern->height);
+
+    while (buffer < end)
+	*buffer++ = xorwow_float (s) < fraction;
+}
+
+void
+pattern_destroy (pattern_t *pattern)
+{
+    free (pattern->buffer);
+}
+
+/* Dither arrays */
+typedef struct array_t {
+    int width;
+    int height;
+    uint32_t *buffer;
+} array_t;
+
+bool_t
+array_init (array_t *array, int width, int height)
+{
+    uint32_t *buffer;
+
+    if (!array)
+	return FALSE;
+
+    buffer = malloc_abc (width, height, sizeof (uint32_t));
+
+    if (!buffer)
+	return FALSE;
+
+    array->buffer = buffer;
+    array->width  = width;
+    array->height = height;
+
+    return TRUE;
+}
+
+uint32_t *
+array_get (array_t *array, int x, int y)
+{
+    return &array->buffer[y * array->width + x];
+}
+
+bool_t
+array_save_ppm (array_t *array, const char *filename)
+{
+    FILE *f = fopen(filename, "wb");
+
+    int i   = 0;
+    int bpp = 2;
+    uint8_t buffer[1024];
+
+    if (!f)
+	return FALSE;
+
+    if (array->width * array->height - 1 < 256)
+	bpp = 1;
+
+    fprintf(f, "P5 %d %d %d\n", array->width, array->height,
+	    array->width * array->height - 1);
+    while (i < array->width * array->height)
+    {
+	    int j = 0;
+	    for (; j < 1024 / bpp && j < array->width * array->height; ++j)
+	    {
+		    uint32_t v = array->buffer[i + j];
+		    if (bpp == 2)
+		    {
+			buffer[2 * j] = v & 0xff;
+			buffer[2 * j + 1] = (v & 0xff00) >> 8;
+		    } else {
+			buffer[j] = v;
+		    }
+	    }
+
+	    fwrite((void *)buffer, bpp, j, f);
+	    i += j;
+    }
+
+    if (fclose(f) != 0)
+	return FALSE;
+
+    return TRUE;
+}
+
+bool_t
+array_save (array_t *array, const char *filename)
+{
+    int x, y;
+    FILE *f = fopen(filename, "wb");
+
+    if (!f)
+	return FALSE;
+
+    fprintf (f, 
+"/* WARNING: This file is generated by make-blue-noise.c\n"
+" * Please edit that file instead of this one.\n"
+" */\n"
+"\n"
+"#ifndef BLUE_NOISE_%dX%d_H\n"
+"#define BLUE_NOISE_%dX%d_H\n"
+"\n"
+"#include <stdint.h>\n"
+"\n", array->width, array->height, array->width, array->height);
+
+    fprintf (f, "static const uint32_t dither_blue_noise_%dx%d[%d] = {\n",
+	     array->width, array->height, array->width * array->height);
+
+    for (y = 0; y < array->height; ++y)
+    {
+	fprintf (f, "    ");
+	for (x = 0; x < array->width; ++x)
+	{
+	    if (x != 0)
+		fprintf (f, ", ");
+
+	    fprintf (f, "%d", *array_get (array, x, y));
+	}
+
+	fprintf (f, ",\n");
+    }
+    fprintf (f, "};\n");
+
+    fprintf (f, "\n#endif /* BLUE_NOISE_%dX%d_H */\n",
+	     array->width, array->height);
+
+    if (fclose(f) != 0)
+	return FALSE;
+
+    return TRUE;
+}
+
+void
+array_destroy (array_t *array)
+{
+    free (array->buffer);
+}
+
+/* Dither array generation */
+bool_t
+compute_cluster_sizes (pattern_t *pattern, matrix_t *matrix)
+{
+    int width  = pattern->width,
+	height = pattern->height;
+
+    if (matrix->width != width || matrix->height != height)
+	return FALSE;
+
+    int px, py, qx, qy, dx, dy;
+    float tsqsi = 2.f * 1.5f * 1.5f;
+
+#ifdef USE_OPENMP
+#pragma omp parallel for default (none) \
+    private (py, px, qy, qx, dx, dy) \
+    shared (height, width, pattern, matrix, tsqsi)
+#endif
+    for (py = 0; py < height; ++py)
+    {
+	for (px = 0; px < width; ++px)
+	{
+	    bool_t pixel = *pattern_get (pattern, px, py);
+	    float dist   = 0.f;
+
+	    for (qx = 0; qx < width; ++qx)
+	    {
+		dx = imin (abs (qx - px), width - abs (qx - px));
+		dx = dx * dx;
+
+		for (qy = 0; qy < height; ++qy)
+		{
+		    dy = imin (abs (qy - py), height - abs (qy - py));
+		    dy = dy * dy;
+
+		    dist += (pixel == *pattern_get (pattern, qx, qy))
+			* expf (- (dx + dy) / tsqsi);
+		}
+	    }
+
+	    *matrix_get (matrix, px, py) = dist;
+	}
+    }
+
+    return TRUE;
+}
+
+bool_t
+swap_pixel (pattern_t *pattern, matrix_t *matrix, int x, int y)
+{
+    int width  = pattern->width,
+	height = pattern->height;
+
+    bool_t new;
+
+    float f,
+          dist  = 0.f,
+	  tsqsi = 2.f * 1.5f * 1.5f;
+
+    int px, py, dx, dy;
+    bool_t b;
+
+    new = !*pattern_get (pattern, x, y);
+    *pattern_get (pattern, x, y) = new;
+
+    if (matrix->width != width || matrix->height != height)
+	return FALSE;
+
+
+#ifdef USE_OPENMP
+#pragma omp parallel for reduction (+:dist) default (none) \
+    private (px, py, dx, dy, b, f) \
+    shared (x, y, width, height, pattern, matrix, new, tsqsi)
+#endif
+    for (py = 0; py < height; ++py)
+    {
+	dy = imin (abs (py - y), height - abs (py - y));
+	dy = dy * dy;
+
+	for (px = 0; px < width; ++px)
+	{
+	    dx = imin (abs (px - x), width - abs (px - x));
+	    dx = dx * dx;
+
+	    b = (*pattern_get (pattern, px, py) == new);
+	    f = expf (- (dx + dy) / tsqsi);
+	    *matrix_get (matrix, px, py) += (2 * b - 1) * f;
+
+	    dist += b * f;
+	}
+    }
+
+    *matrix_get (matrix, x, y) = dist;
+    return TRUE;
+}
+
+void
+largest_cluster (pattern_t *pattern, matrix_t *matrix,
+		 bool_t pixel, int *xmax, int *ymax)
+{
+    int width       = pattern->width,
+	height      = pattern->height;
+
+    int   x, y;
+
+    float vmax = -INFINITY;
+
+#ifdef USE_OPENMP
+#pragma omp parallel default (none) \
+    private (x, y) \
+    shared (height, width, pattern, matrix, pixel, xmax, ymax, vmax)
+#endif
+    {
+	int xbest = -1,
+	    ybest = -1;
+
+#ifdef USE_OPENMP
+	float vbest = -INFINITY;
+
+#pragma omp for reduction (max: vmax) collapse (2)
+#endif
+	for (y = 0; y < height; ++y)
+	{
+	    for (x = 0; x < width; ++x)
+	    {
+		if (*pattern_get (pattern, x, y) != pixel)
+		    continue;
+
+		if (*matrix_get (matrix, x, y) > vmax)
+		{
+		    vmax = *matrix_get (matrix, x, y);
+#ifdef USE_OPENMP
+		    vbest = vmax;
+#endif
+		    xbest = x;
+		    ybest = y;
+		}
+	    }
+	}
+
+#ifdef USE_OPENMP
+#pragma omp barrier
+#pragma omp critical
+	{
+	    if (vmax == vbest)
+	    {
+		*xmax = xbest;
+		*ymax = ybest;
+	    }
+	}
+#else
+	*xmax = xbest;
+	*ymax = ybest;
+#endif
+    }
+
+    assert (vmax > -INFINITY);
+}
+
+void
+generate_initial_binary_pattern (pattern_t *pattern, matrix_t *matrix)
+{
+    int xcluster = 0,
+	ycluster = 0,
+	xvoid    = 0,
+	yvoid    = 0;
+
+    for (;;)
+    {
+	largest_cluster (pattern, matrix, TRUE, &xcluster, &ycluster);
+	assert (*pattern_get (pattern, xcluster, ycluster) == TRUE);
+	swap_pixel (pattern, matrix, xcluster, ycluster);
+
+	largest_cluster (pattern, matrix, FALSE, &xvoid, &yvoid);
+	assert (*pattern_get (pattern, xvoid, yvoid) == FALSE);
+	swap_pixel (pattern, matrix, xvoid, yvoid);
+
+	if (xcluster == xvoid && ycluster == yvoid)
+	    return;
+    }
+}
+
+bool_t
+generate_dither_array (array_t *array,
+		       pattern_t const *prototype, matrix_t const *matrix,
+		       pattern_t *temp_pattern, matrix_t *temp_matrix)
+{
+    int width        = prototype->width,
+	height       = prototype->height;
+
+    int x, y, rank;
+
+    int initial_rank = 0;
+
+    if (array->width != width || array->height != height)
+	return FALSE;
+
+    // Make copies of the prototype and associated sizes matrix since we will
+    // trash them
+    if (!pattern_copy (temp_pattern, prototype))
+	return FALSE;
+
+    if (!matrix_copy (temp_matrix, matrix))
+	return FALSE;
+
+    // Compute initial rank
+    for (y = 0; y < height; ++y)
+    {
+	for (x = 0; x < width; ++x)
+	{
+	    if (*pattern_get (temp_pattern, x, y))
+		initial_rank += 1;
+
+	    *array_get (array, x, y) = 0;
+	}
+    }
+
+    // Phase 1
+    for (rank = initial_rank; rank > 0; --rank)
+    {
+	largest_cluster (temp_pattern, temp_matrix, TRUE, &x, &y);
+	swap_pixel (temp_pattern, temp_matrix, x, y);
+	*array_get (array, x, y) = rank - 1;
+    }
+
+    // Make copies again for phases 2 & 3
+    if (!pattern_copy (temp_pattern, prototype))
+	return FALSE;
+
+    if (!matrix_copy (temp_matrix, matrix))
+	return FALSE;
+
+    // Phase 2 & 3
+    for (rank = initial_rank; rank < width * height; ++rank)
+    {
+	largest_cluster (temp_pattern, temp_matrix, FALSE, &x, &y);
+	swap_pixel (temp_pattern, temp_matrix, x, y);
+	*array_get (array, x, y) = rank;
+    }
+
+    return TRUE;
+}
+
+bool_t
+generate (int size, xorwow_state_t *s,
+	  char const *c_filename, char const *ppm_filename)
+{
+    bool_t ok = TRUE;
+
+    pattern_t prototype, temp_pattern;
+    array_t   array;
+    matrix_t  matrix, temp_matrix;
+
+    printf ("Generating %dx%d blue noise...\n", size, size);
+
+    if (!pattern_init (&prototype, size, size))
+	return FALSE;
+
+    if (!pattern_init (&temp_pattern, size, size))
+    {
+	pattern_destroy (&prototype);
+	return FALSE;
+    }
+
+    if (!matrix_init (&matrix, size, size))
+    {
+	pattern_destroy (&temp_pattern);
+	pattern_destroy (&prototype);
+	return FALSE;
+    }
+
+    if (!matrix_init (&temp_matrix, size, size))
+    {
+	matrix_destroy (&matrix);
+	pattern_destroy (&temp_pattern);
+	pattern_destroy (&prototype);
+	return FALSE;
+    }
+
+    if (!array_init (&array, size, size))
+    {
+	matrix_destroy (&temp_matrix);
+	matrix_destroy (&matrix);
+	pattern_destroy (&temp_pattern);
+	pattern_destroy (&prototype);
+	return FALSE;
+    }
+
+    printf("Filling initial binary pattern with white noise...\n");
+    pattern_fill_white_noise (&prototype, .1, s);
+
+    printf("Initializing cluster sizes...\n");
+    if (!compute_cluster_sizes (&prototype, &matrix))
+    {
+	fprintf (stderr, "Error while computing cluster sizes\n");
+	ok = FALSE;
+	goto out;
+    }
+
+    printf("Generating initial binary pattern...\n");
+    generate_initial_binary_pattern (&prototype, &matrix);
+
+    printf("Generating dither array...\n");
+    if (!generate_dither_array (&array, &prototype, &matrix,
+			 &temp_pattern, &temp_matrix))
+    {
+	fprintf (stderr, "Error while generating dither array\n");
+	ok = FALSE;
+	goto out;
+    }
+
+    printf("Saving dither array...\n");
+    if (!array_save (&array, c_filename))
+    {
+	fprintf (stderr, "Error saving dither array\n");
+	ok = FALSE;
+	goto out;
+    }
+
+#if SAVE_PPM
+    if (!array_save_ppm (&array, ppm_filename))
+    {
+	fprintf (stderr, "Error saving dither array PPM\n");
+	ok = FALSE;
+	goto out;
+    }
+#else
+    (void)ppm_filename;
+#endif
+
+    printf("All done!\n");
+
+out:
+    array_destroy (&array);
+    matrix_destroy (&temp_matrix);
+    matrix_destroy (&matrix);
+    pattern_destroy (&temp_pattern);
+    pattern_destroy (&prototype);
+    return ok;
+}
+
+int
+main (void)
+{
+    xorwow_state_t s = {1185956906, 12385940, 983948, 349208051, 901842};
+
+    if (!generate (64, &s, "blue-noise-64x64.h", "blue-noise-64x64.ppm"))
+	return -1;
+
+    return 0;
+}
diff --git a/pixman/pixman-bits-image.c b/pixman/pixman-bits-image.c
index fe3919b..3b2822c 100644
--- a/pixman/pixman-bits-image.c
+++ b/pixman/pixman-bits-image.c
@@ -35,6 +35,7 @@ 
 #include "pixman-private.h"
 #include "pixman-combine32.h"
 #include "pixman-inlines.h"
+#include "dither/blue-noise-64x64.h"
 
 /* Fetch functions */
 
@@ -1048,6 +1049,15 @@  dest_write_back_narrow (pixman_iter_t *iter)
     iter->y++;
 }
 
+static const float
+dither_factor_blue_noise_64 (int x, int y)
+{
+    float m = dither_blue_noise_64x64[(y % 64) * 64 + x % 64];
+    float f = 64 * 64;
+
+    return m * (1. / f) + (1. / (2. * f));
+}
+
 static const float
 dither_factor_bayer_8 (int x, int y)
 {
@@ -1168,9 +1178,13 @@  dest_write_back_wide (pixman_iter_t *iter)
     case PIXMAN_DITHER_NONE:
 	break;
 
-    case PIXMAN_DITHER_FAST:
     case PIXMAN_DITHER_GOOD:
     case PIXMAN_DITHER_BEST:
+    case PIXMAN_DITHER_ORDERED_BLUE_NOISE_64:
+	buffer = dither_apply_ordered (iter, dither_factor_blue_noise_64);
+	break;
+
+    case PIXMAN_DITHER_FAST:
     case PIXMAN_DITHER_ORDERED_BAYER_8:
 	buffer = dither_apply_ordered (iter, dither_factor_bayer_8);
 	break;
diff --git a/pixman/pixman.h b/pixman/pixman.h
index 1f63f55..62dfb6a 100644
--- a/pixman/pixman.h
+++ b/pixman/pixman.h
@@ -292,6 +292,7 @@  typedef enum
     PIXMAN_DITHER_GOOD,
     PIXMAN_DITHER_BEST,
     PIXMAN_DITHER_ORDERED_BAYER_8,
+    PIXMAN_DITHER_ORDERED_BLUE_NOISE_64,
 } pixman_dither_t;
 
 typedef enum
diff --git a/test/tolerance-test.c b/test/tolerance-test.c
index 011cdb4..3c6e818 100644
--- a/test/tolerance-test.c
+++ b/test/tolerance-test.c
@@ -79,6 +79,7 @@  static const pixman_op_t operators[] =
 static const pixman_dither_t dithers[] =
 {
     PIXMAN_DITHER_ORDERED_BAYER_8,
+    PIXMAN_DITHER_ORDERED_BLUE_NOISE_64,
 };
 
 #define RANDOM_ELT(array)                                               \
diff --git a/test/utils.c b/test/utils.c
index 9ce7a6c..2e3b547 100644
--- a/test/utils.c
+++ b/test/utils.c
@@ -1193,6 +1193,7 @@  static const dither_entry_t dither_list[] =
      */
 
     ENTRY (ORDERED_BAYER_8),
+    ENTRY (ORDERED_BLUE_NOISE_64),
     ENTRY (NONE),
 
 #undef ENTRY