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src/Source/LibWebP/src/enc/enc.picture_csp.c  view on Meta::CPAN

      UpdateW(src2, best_rgb_y + 1 * w, w);
      UpdateChroma(src1, src2, best_rgb_uv, NULL, uv_w);

      // update two rows of Y and one row of RGB
      for (i = 0; i < 2 * w; ++i) {
        const int off = i + j * w;
        const int diff_y = target_y[off] - best_rgb_y[i];
        const int new_y = (int)best_y[off] + diff_y;
        best_y[off] = clip_y(new_y);
      }
      for (i = 0; i < uv_w; ++i) {
        const int off = 3 * (i + (j >> 1) * uv_w);
        int W;
        for (k = 0; k <= 2; ++k) {
          const int diff_uv = (int)target_uv[off + k] - best_rgb_uv[3 * i + k];
          best_uv[off + k] += diff_uv;
        }
        W = RGBToGray(best_uv[off + 0], best_uv[off + 1], best_uv[off + 2]);
        for (k = 0; k <= 2; ++k) {
          best_uv[off + k] -= W;
        }
      }
    }
    // TODO(skal): add early-termination criterion
  }

  // final reconstruction
  ok = ConvertWRGBToYUV(best_y, best_uv, picture);

 End:
  WebPSafeFree(best_y);
  WebPSafeFree(best_uv);
  WebPSafeFree(target_y);
  WebPSafeFree(target_uv);
  WebPSafeFree(best_rgb_y);
  WebPSafeFree(best_rgb_uv);
  WebPSafeFree(tmp_buffer);
  return ok;
}
#undef SAFE_ALLOC

//------------------------------------------------------------------------------
// "Fast" regular RGB->YUV

#define SUM4(ptr, step) LinearToGamma(                     \
    GammaToLinear((ptr)[0]) +                              \
    GammaToLinear((ptr)[(step)]) +                         \
    GammaToLinear((ptr)[rgb_stride]) +                     \
    GammaToLinear((ptr)[rgb_stride + (step)]), 0)          \

#define SUM2(ptr) \
    LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[rgb_stride]), 1)

#define SUM2ALPHA(ptr) ((ptr)[0] + (ptr)[rgb_stride])
#define SUM4ALPHA(ptr) (SUM2ALPHA(ptr) + SUM2ALPHA((ptr) + 4))

#if defined(USE_INVERSE_ALPHA_TABLE)

static const int kAlphaFix = 19;
// Following table is (1 << kAlphaFix) / a. The (v * kInvAlpha[a]) >> kAlphaFix
// formula is then equal to v / a in most (99.6%) cases. Note that this table
// and constant are adjusted very tightly to fit 32b arithmetic.
// In particular, they use the fact that the operands for 'v / a' are actually
// derived as v = (a0.p0 + a1.p1 + a2.p2 + a3.p3) and a = a0 + a1 + a2 + a3
// with ai in [0..255] and pi in [0..1<<kGammaFix). The constraint to avoid
// overflow is: kGammaFix + kAlphaFix <= 31.
static const uint32_t kInvAlpha[4 * 0xff + 1] = {
  0,  /* alpha = 0 */
  524288, 262144, 174762, 131072, 104857, 87381, 74898, 65536,
  58254, 52428, 47662, 43690, 40329, 37449, 34952, 32768,
  30840, 29127, 27594, 26214, 24966, 23831, 22795, 21845,
  20971, 20164, 19418, 18724, 18078, 17476, 16912, 16384,
  15887, 15420, 14979, 14563, 14169, 13797, 13443, 13107,
  12787, 12483, 12192, 11915, 11650, 11397, 11155, 10922,
  10699, 10485, 10280, 10082, 9892, 9709, 9532, 9362,
  9198, 9039, 8886, 8738, 8594, 8456, 8322, 8192,
  8065, 7943, 7825, 7710, 7598, 7489, 7384, 7281,
  7182, 7084, 6990, 6898, 6808, 6721, 6636, 6553,
  6472, 6393, 6316, 6241, 6168, 6096, 6026, 5957,
  5890, 5825, 5761, 5698, 5637, 5577, 5518, 5461,
  5405, 5349, 5295, 5242, 5190, 5140, 5090, 5041,
  4993, 4946, 4899, 4854, 4809, 4766, 4723, 4681,
  4639, 4599, 4559, 4519, 4481, 4443, 4405, 4369,
  4332, 4297, 4262, 4228, 4194, 4161, 4128, 4096,
  4064, 4032, 4002, 3971, 3942, 3912, 3883, 3855,
  3826, 3799, 3771, 3744, 3718, 3692, 3666, 3640,
  3615, 3591, 3566, 3542, 3518, 3495, 3472, 3449,
  3426, 3404, 3382, 3360, 3339, 3318, 3297, 3276,
  3256, 3236, 3216, 3196, 3177, 3158, 3139, 3120,
  3102, 3084, 3066, 3048, 3030, 3013, 2995, 2978,
  2962, 2945, 2928, 2912, 2896, 2880, 2864, 2849,
  2833, 2818, 2803, 2788, 2774, 2759, 2744, 2730,
  2716, 2702, 2688, 2674, 2661, 2647, 2634, 2621,
  2608, 2595, 2582, 2570, 2557, 2545, 2532, 2520,
  2508, 2496, 2484, 2473, 2461, 2449, 2438, 2427,
  2416, 2404, 2394, 2383, 2372, 2361, 2351, 2340,
  2330, 2319, 2309, 2299, 2289, 2279, 2269, 2259,
  2250, 2240, 2231, 2221, 2212, 2202, 2193, 2184,
  2175, 2166, 2157, 2148, 2139, 2131, 2122, 2114,
  2105, 2097, 2088, 2080, 2072, 2064, 2056, 2048,
  2040, 2032, 2024, 2016, 2008, 2001, 1993, 1985,
  1978, 1971, 1963, 1956, 1949, 1941, 1934, 1927,
  1920, 1913, 1906, 1899, 1892, 1885, 1879, 1872,
  1865, 1859, 1852, 1846, 1839, 1833, 1826, 1820,
  1814, 1807, 1801, 1795, 1789, 1783, 1777, 1771,
  1765, 1759, 1753, 1747, 1741, 1736, 1730, 1724,
  1718, 1713, 1707, 1702, 1696, 1691, 1685, 1680,
  1675, 1669, 1664, 1659, 1653, 1648, 1643, 1638,
  1633, 1628, 1623, 1618, 1613, 1608, 1603, 1598,
  1593, 1588, 1583, 1579, 1574, 1569, 1565, 1560,
  1555, 1551, 1546, 1542, 1537, 1533, 1528, 1524,
  1519, 1515, 1510, 1506, 1502, 1497, 1493, 1489,
  1485, 1481, 1476, 1472, 1468, 1464, 1460, 1456,
  1452, 1448, 1444, 1440, 1436, 1432, 1428, 1424,
  1420, 1416, 1413, 1409, 1405, 1401, 1398, 1394,
  1390, 1387, 1383, 1379, 1376, 1372, 1368, 1365,
  1361, 1358, 1354, 1351, 1347, 1344, 1340, 1337,
  1334, 1330, 1327, 1323, 1320, 1317, 1314, 1310,
  1307, 1304, 1300, 1297, 1294, 1291, 1288, 1285,
  1281, 1278, 1275, 1272, 1269, 1266, 1263, 1260,
  1257, 1254, 1251, 1248, 1245, 1242, 1239, 1236,