| // Copyright 2012 Google Inc. All Rights Reserved. |
| // |
| // This code is licensed under the same terms as WebM: |
| // Software License Agreement: http://www.webmproject.org/license/software/ |
| // Additional IP Rights Grant: http://www.webmproject.org/license/additional/ |
| // ----------------------------------------------------------------------------- |
| // |
| // Image transforms and color space conversion methods for lossless decoder. |
| // |
| // Authors: Vikas Arora (vikaas.arora@gmail.com) |
| // Jyrki Alakuijala (jyrki@google.com) |
| // Urvang Joshi (urvang@google.com) |
| |
| #if defined(__cplusplus) || defined(c_plusplus) |
| extern "C" { |
| #endif |
| |
| #include <math.h> |
| #include <stdlib.h> |
| #include "./lossless.h" |
| #include "../dec/vp8li.h" |
| #include "../dsp/yuv.h" |
| #include "../dsp/dsp.h" |
| #include "../enc/histogram.h" |
| |
| // A lookup table for small values of log(int) to be used in entropy |
| // computation. |
| // |
| // ", ".join(["%.16ff" % x for x in [0.0]+[log(x) for x in range(1, 256)]]) |
| #define LOG_LOOKUP_IDX_MAX 256 |
| static const float kLogTable[LOG_LOOKUP_IDX_MAX] = { |
| 0.0000000000000000f, 0.0000000000000000f, 0.6931471805599453f, |
| 1.0986122886681098f, 1.3862943611198906f, 1.6094379124341003f, |
| 1.7917594692280550f, 1.9459101490553132f, 2.0794415416798357f, |
| 2.1972245773362196f, 2.3025850929940459f, 2.3978952727983707f, |
| 2.4849066497880004f, 2.5649493574615367f, 2.6390573296152584f, |
| 2.7080502011022101f, 2.7725887222397811f, 2.8332133440562162f, |
| 2.8903717578961645f, 2.9444389791664403f, 2.9957322735539909f, |
| 3.0445224377234230f, 3.0910424533583161f, 3.1354942159291497f, |
| 3.1780538303479458f, 3.2188758248682006f, 3.2580965380214821f, |
| 3.2958368660043291f, 3.3322045101752038f, 3.3672958299864741f, |
| 3.4011973816621555f, 3.4339872044851463f, 3.4657359027997265f, |
| 3.4965075614664802f, 3.5263605246161616f, 3.5553480614894135f, |
| 3.5835189384561099f, 3.6109179126442243f, 3.6375861597263857f, |
| 3.6635616461296463f, 3.6888794541139363f, 3.7135720667043080f, |
| 3.7376696182833684f, 3.7612001156935624f, 3.7841896339182610f, |
| 3.8066624897703196f, 3.8286413964890951f, 3.8501476017100584f, |
| 3.8712010109078911f, 3.8918202981106265f, 3.9120230054281460f, |
| 3.9318256327243257f, 3.9512437185814275f, 3.9702919135521220f, |
| 3.9889840465642745f, 4.0073331852324712f, 4.0253516907351496f, |
| 4.0430512678345503f, 4.0604430105464191f, 4.0775374439057197f, |
| 4.0943445622221004f, 4.1108738641733114f, 4.1271343850450917f, |
| 4.1431347263915326f, 4.1588830833596715f, 4.1743872698956368f, |
| 4.1896547420264252f, 4.2046926193909657f, 4.2195077051761070f, |
| 4.2341065045972597f, 4.2484952420493594f, 4.2626798770413155f, |
| 4.2766661190160553f, 4.2904594411483910f, 4.3040650932041702f, |
| 4.3174881135363101f, 4.3307333402863311f, 4.3438054218536841f, |
| 4.3567088266895917f, 4.3694478524670215f, 4.3820266346738812f, |
| 4.3944491546724391f, 4.4067192472642533f, 4.4188406077965983f, |
| 4.4308167988433134f, 4.4426512564903167f, 4.4543472962535073f, |
| 4.4659081186545837f, 4.4773368144782069f, 4.4886363697321396f, |
| 4.4998096703302650f, 4.5108595065168497f, 4.5217885770490405f, |
| 4.5325994931532563f, 4.5432947822700038f, 4.5538768916005408f, |
| 4.5643481914678361f, 4.5747109785033828f, 4.5849674786705723f, |
| 4.5951198501345898f, 4.6051701859880918f, 4.6151205168412597f, |
| 4.6249728132842707f, 4.6347289882296359f, 4.6443908991413725f, |
| 4.6539603501575231f, 4.6634390941120669f, 4.6728288344619058f, |
| 4.6821312271242199f, 4.6913478822291435f, 4.7004803657924166f, |
| 4.7095302013123339f, 4.7184988712950942f, 4.7273878187123408f, |
| 4.7361984483944957f, 4.7449321283632502f, 4.7535901911063645f, |
| 4.7621739347977563f, 4.7706846244656651f, 4.7791234931115296f, |
| 4.7874917427820458f, 4.7957905455967413f, 4.8040210447332568f, |
| 4.8121843553724171f, 4.8202815656050371f, 4.8283137373023015f, |
| 4.8362819069514780f, 4.8441870864585912f, 4.8520302639196169f, |
| 4.8598124043616719f, 4.8675344504555822f, 4.8751973232011512f, |
| 4.8828019225863706f, 4.8903491282217537f, 4.8978397999509111f, |
| 4.9052747784384296f, 4.9126548857360524f, 4.9199809258281251f, |
| 4.9272536851572051f, 4.9344739331306915f, 4.9416424226093039f, |
| 4.9487598903781684f, 4.9558270576012609f, 4.9628446302599070f, |
| 4.9698132995760007f, 4.9767337424205742f, 4.9836066217083363f, |
| 4.9904325867787360f, 4.9972122737641147f, 5.0039463059454592f, |
| 5.0106352940962555f, 5.0172798368149243f, 5.0238805208462765f, |
| 5.0304379213924353f, 5.0369526024136295f, 5.0434251169192468f, |
| 5.0498560072495371f, 5.0562458053483077f, 5.0625950330269669f, |
| 5.0689042022202315f, 5.0751738152338266f, 5.0814043649844631f, |
| 5.0875963352323836f, 5.0937502008067623f, 5.0998664278241987f, |
| 5.1059454739005803f, 5.1119877883565437f, 5.1179938124167554f, |
| 5.1239639794032588f, 5.1298987149230735f, 5.1357984370502621f, |
| 5.1416635565026603f, 5.1474944768134527f, 5.1532915944977793f, |
| 5.1590552992145291f, 5.1647859739235145f, 5.1704839950381514f, |
| 5.1761497325738288f, 5.1817835502920850f, 5.1873858058407549f, |
| 5.1929568508902104f, 5.1984970312658261f, 5.2040066870767951f, |
| 5.2094861528414214f, 5.2149357576089859f, 5.2203558250783244f, |
| 5.2257466737132017f, 5.2311086168545868f, 5.2364419628299492f, |
| 5.2417470150596426f, 5.2470240721604862f, 5.2522734280466299f, |
| 5.2574953720277815f, 5.2626901889048856f, 5.2678581590633282f, |
| 5.2729995585637468f, 5.2781146592305168f, 5.2832037287379885f, |
| 5.2882670306945352f, 5.2933048247244923f, 5.2983173665480363f, |
| 5.3033049080590757f, 5.3082676974012051f, 5.3132059790417872f, |
| 5.3181199938442161f, 5.3230099791384085f, 5.3278761687895813f, |
| 5.3327187932653688f, 5.3375380797013179f, 5.3423342519648109f, |
| 5.3471075307174685f, 5.3518581334760666f, 5.3565862746720123f, |
| 5.3612921657094255f, 5.3659760150218512f, 5.3706380281276624f, |
| 5.3752784076841653f, 5.3798973535404597f, 5.3844950627890888f, |
| 5.3890717298165010f, 5.3936275463523620f, 5.3981627015177525f, |
| 5.4026773818722793f, 5.4071717714601188f, 5.4116460518550396f, |
| 5.4161004022044201f, 5.4205349992722862f, 5.4249500174814029f, |
| 5.4293456289544411f, 5.4337220035542400f, 5.4380793089231956f, |
| 5.4424177105217932f, 5.4467373716663099f, 5.4510384535657002f, |
| 5.4553211153577017f, 5.4595855141441589f, 5.4638318050256105f, |
| 5.4680601411351315f, 5.4722706736714750f, 5.4764635519315110f, |
| 5.4806389233419912f, 5.4847969334906548f, 5.4889377261566867f, |
| 5.4930614433405482f, 5.4971682252932021f, 5.5012582105447274f, |
| 5.5053315359323625f, 5.5093883366279774f, 5.5134287461649825f, |
| 5.5174528964647074f, 5.5214609178622460f, 5.5254529391317835f, |
| 5.5294290875114234f, 5.5333894887275203f, 5.5373342670185366f, |
| 5.5412635451584258f |
| }; |
| |
| #define APPROX_LOG_MAX 4096 |
| #define LOG_2_BASE_E 0.6931471805599453f |
| |
| float VP8LFastLog(int v) { |
| if (v < APPROX_LOG_MAX) { |
| int log_cnt = 0; |
| while (v >= LOG_LOOKUP_IDX_MAX) { |
| ++log_cnt; |
| v = v >> 1; |
| } |
| return kLogTable[v] + (log_cnt * LOG_2_BASE_E); |
| } |
| return (float)log(v); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Image transforms. |
| |
| // In-place sum of each component with mod 256. |
| static WEBP_INLINE void AddPixelsEq(uint32_t* a, uint32_t b) { |
| const uint32_t alpha_and_green = (*a & 0xff00ff00u) + (b & 0xff00ff00u); |
| const uint32_t red_and_blue = (*a & 0x00ff00ffu) + (b & 0x00ff00ffu); |
| *a = (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu); |
| } |
| |
| static WEBP_INLINE uint32_t Average2(uint32_t a0, uint32_t a1) { |
| return (((a0 ^ a1) & 0xfefefefeL) >> 1) + (a0 & a1); |
| } |
| |
| static WEBP_INLINE uint32_t Average3(uint32_t a0, uint32_t a1, uint32_t a2) { |
| return Average2(Average2(a0, a2), a1); |
| } |
| |
| static WEBP_INLINE uint32_t Average4(uint32_t a0, uint32_t a1, |
| uint32_t a2, uint32_t a3) { |
| return Average2(Average2(a0, a1), Average2(a2, a3)); |
| } |
| |
| static WEBP_INLINE uint32_t Clip255(uint32_t a) { |
| if (a < 256) { |
| return a; |
| } |
| // return 0, when a is a negative integer. |
| // return 255, when a is positive. |
| return ~a >> 24; |
| } |
| |
| static WEBP_INLINE int AddSubtractComponentFull(int a, int b, int c) { |
| return Clip255(a + b - c); |
| } |
| |
| static WEBP_INLINE uint32_t ClampedAddSubtractFull(uint32_t c0, uint32_t c1, |
| uint32_t c2) { |
| const int a = AddSubtractComponentFull(c0 >> 24, c1 >> 24, c2 >> 24); |
| const int r = AddSubtractComponentFull((c0 >> 16) & 0xff, |
| (c1 >> 16) & 0xff, |
| (c2 >> 16) & 0xff); |
| const int g = AddSubtractComponentFull((c0 >> 8) & 0xff, |
| (c1 >> 8) & 0xff, |
| (c2 >> 8) & 0xff); |
| const int b = AddSubtractComponentFull(c0 & 0xff, c1 & 0xff, c2 & 0xff); |
| return (a << 24) | (r << 16) | (g << 8) | b; |
| } |
| |
| static WEBP_INLINE int AddSubtractComponentHalf(int a, int b) { |
| return Clip255(a + (a - b) / 2); |
| } |
| |
| static WEBP_INLINE uint32_t ClampedAddSubtractHalf(uint32_t c0, uint32_t c1, |
| uint32_t c2) { |
| const uint32_t ave = Average2(c0, c1); |
| const int a = AddSubtractComponentHalf(ave >> 24, c2 >> 24); |
| const int r = AddSubtractComponentHalf((ave >> 16) & 0xff, (c2 >> 16) & 0xff); |
| const int g = AddSubtractComponentHalf((ave >> 8) & 0xff, (c2 >> 8) & 0xff); |
| const int b = AddSubtractComponentHalf((ave >> 0) & 0xff, (c2 >> 0) & 0xff); |
| return (a << 24) | (r << 16) | (g << 8) | b; |
| } |
| |
| static WEBP_INLINE int Sub3(int a, int b, int c) { |
| const int pa = b - c; |
| const int pb = a - c; |
| return abs(pa) - abs(pb); |
| } |
| |
| static WEBP_INLINE uint32_t Select(uint32_t a, uint32_t b, uint32_t c) { |
| const int pa_minus_pb = |
| Sub3((a >> 24) , (b >> 24) , (c >> 24) ) + |
| Sub3((a >> 16) & 0xff, (b >> 16) & 0xff, (c >> 16) & 0xff) + |
| Sub3((a >> 8) & 0xff, (b >> 8) & 0xff, (c >> 8) & 0xff) + |
| Sub3((a ) & 0xff, (b ) & 0xff, (c ) & 0xff); |
| |
| return (pa_minus_pb <= 0) ? a : b; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Predictors |
| |
| static uint32_t Predictor0(uint32_t left, const uint32_t* const top) { |
| (void)top; |
| (void)left; |
| return ARGB_BLACK; |
| } |
| static uint32_t Predictor1(uint32_t left, const uint32_t* const top) { |
| (void)top; |
| return left; |
| } |
| static uint32_t Predictor2(uint32_t left, const uint32_t* const top) { |
| (void)left; |
| return top[0]; |
| } |
| static uint32_t Predictor3(uint32_t left, const uint32_t* const top) { |
| (void)left; |
| return top[1]; |
| } |
| static uint32_t Predictor4(uint32_t left, const uint32_t* const top) { |
| (void)left; |
| return top[-1]; |
| } |
| static uint32_t Predictor5(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Average3(left, top[0], top[1]); |
| return pred; |
| } |
| static uint32_t Predictor6(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Average2(left, top[-1]); |
| return pred; |
| } |
| static uint32_t Predictor7(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Average2(left, top[0]); |
| return pred; |
| } |
| static uint32_t Predictor8(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Average2(top[-1], top[0]); |
| (void)left; |
| return pred; |
| } |
| static uint32_t Predictor9(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Average2(top[0], top[1]); |
| (void)left; |
| return pred; |
| } |
| static uint32_t Predictor10(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Average4(left, top[-1], top[0], top[1]); |
| return pred; |
| } |
| static uint32_t Predictor11(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = Select(top[0], left, top[-1]); |
| return pred; |
| } |
| static uint32_t Predictor12(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = ClampedAddSubtractFull(left, top[0], top[-1]); |
| return pred; |
| } |
| static uint32_t Predictor13(uint32_t left, const uint32_t* const top) { |
| const uint32_t pred = ClampedAddSubtractHalf(left, top[0], top[-1]); |
| return pred; |
| } |
| |
| typedef uint32_t (*PredictorFunc)(uint32_t left, const uint32_t* const top); |
| static const PredictorFunc kPredictors[16] = { |
| Predictor0, Predictor1, Predictor2, Predictor3, |
| Predictor4, Predictor5, Predictor6, Predictor7, |
| Predictor8, Predictor9, Predictor10, Predictor11, |
| Predictor12, Predictor13, |
| Predictor0, Predictor0 // <- padding security sentinels |
| }; |
| |
| // TODO(vikasa): Replace 256 etc with defines. |
| static double PredictionCostSpatial(const int* counts, |
| int weight_0, double exp_val) { |
| const int significant_symbols = 16; |
| const double exp_decay_factor = 0.6; |
| double bits = weight_0 * counts[0]; |
| int i; |
| for (i = 1; i < significant_symbols; ++i) { |
| bits += exp_val * (counts[i] + counts[256 - i]); |
| exp_val *= exp_decay_factor; |
| } |
| return -0.1 * bits; |
| } |
| |
| // Compute the Shanon's entropy: Sum(p*log2(p)) |
| static double ShannonEntropy(const int* const array, int n) { |
| int i; |
| double retval = 0; |
| int sum = 0; |
| for (i = 0; i < n; ++i) { |
| if (array[i] != 0) { |
| sum += array[i]; |
| retval += array[i] * VP8LFastLog(array[i]); |
| } |
| } |
| retval -= sum * VP8LFastLog(sum); |
| retval *= -1.4426950408889634; // 1.0 / -FastLog(2); |
| return retval; |
| } |
| |
| static double PredictionCostSpatialHistogram(int accumulated[4][256], |
| int tile[4][256]) { |
| int i; |
| int k; |
| int combo[256]; |
| double retval = 0; |
| for (i = 0; i < 4; ++i) { |
| const double exp_val = 0.94; |
| retval += PredictionCostSpatial(&tile[i][0], 1, exp_val); |
| retval += ShannonEntropy(&tile[i][0], 256); |
| for (k = 0; k < 256; ++k) { |
| combo[k] = accumulated[i][k] + tile[i][k]; |
| } |
| retval += ShannonEntropy(&combo[0], 256); |
| } |
| return retval; |
| } |
| |
| static int GetBestPredictorForTile(int width, int height, |
| int tile_x, int tile_y, int bits, |
| int accumulated[4][256], |
| const uint32_t* const argb_scratch) { |
| const int kNumPredModes = 14; |
| const int col_start = tile_x << bits; |
| const int row_start = tile_y << bits; |
| const int tile_size = 1 << bits; |
| const int ymax = (tile_size <= height - row_start) ? |
| tile_size : height - row_start; |
| const int xmax = (tile_size <= width - col_start) ? |
| tile_size : width - col_start; |
| int histo[4][256]; |
| double best_diff = 1e99; |
| int best_mode = 0; |
| |
| int mode; |
| for (mode = 0; mode < kNumPredModes; ++mode) { |
| const uint32_t* current_row = argb_scratch; |
| const PredictorFunc pred_func = kPredictors[mode]; |
| double cur_diff; |
| int y; |
| memset(&histo[0][0], 0, sizeof(histo)); |
| for (y = 0; y < ymax; ++y) { |
| int x; |
| const int row = row_start + y; |
| const uint32_t* const upper_row = current_row; |
| current_row = upper_row + width; |
| for (x = 0; x < xmax; ++x) { |
| const int col = col_start + x; |
| uint32_t predict; |
| uint32_t predict_diff; |
| if (row == 0) { |
| predict = (col == 0) ? ARGB_BLACK : current_row[col - 1]; // Left. |
| } else if (col == 0) { |
| predict = upper_row[col]; // Top. |
| } else { |
| predict = pred_func(current_row[col - 1], upper_row + col); |
| } |
| predict_diff = VP8LSubPixels(current_row[col], predict); |
| ++histo[0][predict_diff >> 24]; |
| ++histo[1][((predict_diff >> 16) & 0xff)]; |
| ++histo[2][((predict_diff >> 8) & 0xff)]; |
| ++histo[3][(predict_diff & 0xff)]; |
| } |
| } |
| cur_diff = PredictionCostSpatialHistogram(accumulated, histo); |
| if (cur_diff < best_diff) { |
| best_diff = cur_diff; |
| best_mode = mode; |
| } |
| } |
| |
| return best_mode; |
| } |
| |
| static void CopyTileWithPrediction(int width, int height, |
| int tile_x, int tile_y, int bits, int mode, |
| const uint32_t* const argb_scratch, |
| uint32_t* const argb) { |
| const int col_start = tile_x << bits; |
| const int row_start = tile_y << bits; |
| const int tile_size = 1 << bits; |
| const int ymax = (tile_size <= height - row_start) ? |
| tile_size : height - row_start; |
| const int xmax = (tile_size <= width - col_start) ? |
| tile_size : width - col_start; |
| const PredictorFunc pred_func = kPredictors[mode]; |
| const uint32_t* current_row = argb_scratch; |
| |
| int y; |
| for (y = 0; y < ymax; ++y) { |
| int x; |
| const int row = row_start + y; |
| const uint32_t* const upper_row = current_row; |
| current_row = upper_row + width; |
| for (x = 0; x < xmax; ++x) { |
| const int col = col_start + x; |
| const int pix = row * width + col; |
| uint32_t predict; |
| if (row == 0) { |
| predict = (col == 0) ? ARGB_BLACK : current_row[col - 1]; // Left. |
| } else if (col == 0) { |
| predict = upper_row[col]; // Top. |
| } else { |
| predict = pred_func(current_row[col - 1], upper_row + col); |
| } |
| argb[pix] = VP8LSubPixels(current_row[col], predict); |
| } |
| } |
| } |
| |
| void VP8LResidualImage(int width, int height, int bits, |
| uint32_t* const argb, uint32_t* const argb_scratch, |
| uint32_t* const image) { |
| const int max_tile_size = 1 << bits; |
| const int tiles_per_row = VP8LSubSampleSize(width, bits); |
| const int tiles_per_col = VP8LSubSampleSize(height, bits); |
| uint32_t* const upper_row = argb_scratch; |
| uint32_t* const current_tile_rows = argb_scratch + width; |
| int tile_y; |
| int histo[4][256]; |
| memset(histo, 0, sizeof(histo)); |
| for (tile_y = 0; tile_y < tiles_per_col; ++tile_y) { |
| const int tile_y_offset = tile_y * max_tile_size; |
| const int this_tile_height = |
| (tile_y < tiles_per_col - 1) ? max_tile_size : height - tile_y_offset; |
| int tile_x; |
| if (tile_y > 0) { |
| memcpy(upper_row, current_tile_rows + (max_tile_size - 1) * width, |
| width * sizeof(*upper_row)); |
| } |
| memcpy(current_tile_rows, &argb[tile_y_offset * width], |
| this_tile_height * width * sizeof(*current_tile_rows)); |
| for (tile_x = 0; tile_x < tiles_per_row; ++tile_x) { |
| int pred; |
| int y; |
| const int tile_x_offset = tile_x * max_tile_size; |
| int all_x_max = tile_x_offset + max_tile_size; |
| if (all_x_max > width) { |
| all_x_max = width; |
| } |
| pred = GetBestPredictorForTile(width, height, tile_x, tile_y, bits, histo, |
| argb_scratch); |
| image[tile_y * tiles_per_row + tile_x] = 0xff000000u | (pred << 8); |
| CopyTileWithPrediction(width, height, tile_x, tile_y, bits, pred, |
| argb_scratch, argb); |
| for (y = 0; y < max_tile_size; ++y) { |
| int ix; |
| int all_x; |
| int all_y = tile_y_offset + y; |
| if (all_y >= height) { |
| break; |
| } |
| ix = all_y * width + tile_x_offset; |
| for (all_x = tile_x_offset; all_x < all_x_max; ++all_x, ++ix) { |
| const uint32_t a = argb[ix]; |
| ++histo[0][a >> 24]; |
| ++histo[1][((a >> 16) & 0xff)]; |
| ++histo[2][((a >> 8) & 0xff)]; |
| ++histo[3][(a & 0xff)]; |
| } |
| } |
| } |
| } |
| } |
| |
| // Inverse prediction. |
| static void PredictorInverseTransform(const VP8LTransform* const transform, |
| int y_start, int y_end, uint32_t* data) { |
| const int width = transform->xsize_; |
| if (y_start == 0) { // First Row follows the L (mode=1) mode. |
| int x; |
| const uint32_t pred0 = Predictor0(data[-1], NULL); |
| AddPixelsEq(data, pred0); |
| for (x = 1; x < width; ++x) { |
| const uint32_t pred1 = Predictor1(data[x - 1], NULL); |
| AddPixelsEq(data + x, pred1); |
| } |
| data += width; |
| ++y_start; |
| } |
| |
| { |
| int y = y_start; |
| const int mask = (1 << transform->bits_) - 1; |
| const int tiles_per_row = VP8LSubSampleSize(width, transform->bits_); |
| const uint32_t* pred_mode_base = |
| transform->data_ + (y >> transform->bits_) * tiles_per_row; |
| |
| while (y < y_end) { |
| int x; |
| const uint32_t pred2 = Predictor2(data[-1], data - width); |
| const uint32_t* pred_mode_src = pred_mode_base; |
| PredictorFunc pred_func; |
| |
| // First pixel follows the T (mode=2) mode. |
| AddPixelsEq(data, pred2); |
| |
| // .. the rest: |
| pred_func = kPredictors[((*pred_mode_src++) >> 8) & 0xf]; |
| for (x = 1; x < width; ++x) { |
| uint32_t pred; |
| if ((x & mask) == 0) { // start of tile. Read predictor function. |
| pred_func = kPredictors[((*pred_mode_src++) >> 8) & 0xf]; |
| } |
| pred = pred_func(data[x - 1], data + x - width); |
| AddPixelsEq(data + x, pred); |
| } |
| data += width; |
| ++y; |
| if ((y & mask) == 0) { // Use the same mask, since tiles are squares. |
| pred_mode_base += tiles_per_row; |
| } |
| } |
| } |
| } |
| |
| void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs) { |
| int i; |
| for (i = 0; i < num_pixs; ++i) { |
| const uint32_t argb = argb_data[i]; |
| const uint32_t green = (argb >> 8) & 0xff; |
| const uint32_t new_r = (((argb >> 16) & 0xff) - green) & 0xff; |
| const uint32_t new_b = ((argb & 0xff) - green) & 0xff; |
| argb_data[i] = (argb & 0xff00ff00) | (new_r << 16) | new_b; |
| } |
| } |
| |
| // Add green to blue and red channels (i.e. perform the inverse transform of |
| // 'subtract green'). |
| static void AddGreenToBlueAndRed(const VP8LTransform* const transform, |
| int y_start, int y_end, uint32_t* data) { |
| const int width = transform->xsize_; |
| const uint32_t* const data_end = data + (y_end - y_start) * width; |
| while (data < data_end) { |
| const uint32_t argb = *data; |
| // "* 0001001u" is equivalent to "(green << 16) + green)" |
| const uint32_t green = ((argb >> 8) & 0xff); |
| uint32_t red_blue = (argb & 0x00ff00ffu); |
| red_blue += (green << 16) | green; |
| red_blue &= 0x00ff00ffu; |
| *data++ = (argb & 0xff00ff00u) | red_blue; |
| } |
| } |
| |
| typedef struct { |
| // Note: the members are uint8_t, so that any negative values are |
| // automatically converted to "mod 256" values. |
| uint8_t green_to_red_; |
| uint8_t green_to_blue_; |
| uint8_t red_to_blue_; |
| } Multipliers; |
| |
| static WEBP_INLINE void MultipliersClear(Multipliers* m) { |
| m->green_to_red_ = 0; |
| m->green_to_blue_ = 0; |
| m->red_to_blue_ = 0; |
| } |
| |
| static WEBP_INLINE uint32_t ColorTransformDelta(int8_t color_pred, |
| int8_t color) { |
| return (uint32_t)((int)(color_pred) * color) >> 5; |
| } |
| |
| static WEBP_INLINE void ColorCodeToMultipliers(uint32_t color_code, |
| Multipliers* const m) { |
| m->green_to_red_ = (color_code >> 0) & 0xff; |
| m->green_to_blue_ = (color_code >> 8) & 0xff; |
| m->red_to_blue_ = (color_code >> 16) & 0xff; |
| } |
| |
| static WEBP_INLINE uint32_t MultipliersToColorCode(Multipliers* const m) { |
| return 0xff000000u | |
| ((uint32_t)(m->red_to_blue_) << 16) | |
| ((uint32_t)(m->green_to_blue_) << 8) | |
| m->green_to_red_; |
| } |
| |
| static WEBP_INLINE uint32_t TransformColor(const Multipliers* const m, |
| uint32_t argb, int inverse) { |
| const uint32_t green = argb >> 8; |
| const uint32_t red = argb >> 16; |
| uint32_t new_red = red; |
| uint32_t new_blue = argb; |
| |
| if (inverse) { |
| new_red += ColorTransformDelta(m->green_to_red_, green); |
| new_red &= 0xff; |
| new_blue += ColorTransformDelta(m->green_to_blue_, green); |
| new_blue += ColorTransformDelta(m->red_to_blue_, new_red); |
| new_blue &= 0xff; |
| } else { |
| new_red -= ColorTransformDelta(m->green_to_red_, green); |
| new_red &= 0xff; |
| new_blue -= ColorTransformDelta(m->green_to_blue_, green); |
| new_blue -= ColorTransformDelta(m->red_to_blue_, red); |
| new_blue &= 0xff; |
| } |
| return (argb & 0xff00ff00u) | (new_red << 16) | (new_blue); |
| } |
| |
| static WEBP_INLINE int SkipRepeatedPixels(const uint32_t* const argb, |
| int ix, int xsize) { |
| const uint32_t v = argb[ix]; |
| if (ix >= xsize + 3) { |
| if (v == argb[ix - xsize] && |
| argb[ix - 1] == argb[ix - xsize - 1] && |
| argb[ix - 2] == argb[ix - xsize - 2] && |
| argb[ix - 3] == argb[ix - xsize - 3]) { |
| return 1; |
| } |
| return v == argb[ix - 3] && v == argb[ix - 2] && v == argb[ix - 1]; |
| } else if (ix >= 3) { |
| return v == argb[ix - 3] && v == argb[ix - 2] && v == argb[ix - 1]; |
| } |
| return 0; |
| } |
| |
| static double PredictionCostCrossColor(const int accumulated[256], |
| const int counts[256]) { |
| // Favor low entropy, locally and globally. |
| int i; |
| int combo[256]; |
| for (i = 0; i < 256; ++i) { |
| combo[i] = accumulated[i] + counts[i]; |
| } |
| return ShannonEntropy(combo, 256) + |
| ShannonEntropy(counts, 256) + |
| PredictionCostSpatial(counts, 3, 2.4); // Favor small absolute values. |
| } |
| |
| static Multipliers GetBestColorTransformForTile( |
| int tile_x, int tile_y, int bits, |
| Multipliers prevX, |
| Multipliers prevY, |
| int step, int xsize, int ysize, |
| int* accumulated_red_histo, |
| int* accumulated_blue_histo, |
| const uint32_t* const argb) { |
| double best_diff = 1e99; |
| double cur_diff; |
| const int halfstep = step / 2; |
| const int max_tile_size = 1 << bits; |
| const int tile_y_offset = tile_y * max_tile_size; |
| const int tile_x_offset = tile_x * max_tile_size; |
| int green_to_red; |
| int green_to_blue; |
| int red_to_blue; |
| int all_x_max = tile_x_offset + max_tile_size; |
| int all_y_max = tile_y_offset + max_tile_size; |
| Multipliers best_tx; |
| MultipliersClear(&best_tx); |
| if (all_x_max > xsize) { |
| all_x_max = xsize; |
| } |
| if (all_y_max > ysize) { |
| all_y_max = ysize; |
| } |
| for (green_to_red = -64; green_to_red <= 64; green_to_red += halfstep) { |
| int histo[256] = { 0 }; |
| int all_y; |
| Multipliers tx; |
| MultipliersClear(&tx); |
| tx.green_to_red_ = green_to_red & 0xff; |
| |
| for (all_y = tile_y_offset; all_y < all_y_max; ++all_y) { |
| uint32_t predict; |
| int ix = all_y * xsize + tile_x_offset; |
| int all_x; |
| for (all_x = tile_x_offset; all_x < all_x_max; ++all_x, ++ix) { |
| if (SkipRepeatedPixels(argb, ix, xsize)) { |
| continue; |
| } |
| predict = TransformColor(&tx, argb[ix], 0); |
| ++histo[(predict >> 16) & 0xff]; // red. |
| } |
| } |
| cur_diff = PredictionCostCrossColor(&accumulated_red_histo[0], &histo[0]); |
| if (tx.green_to_red_ == prevX.green_to_red_) { |
| cur_diff -= 3; // favor keeping the areas locally similar |
| } |
| if (tx.green_to_red_ == prevY.green_to_red_) { |
| cur_diff -= 3; // favor keeping the areas locally similar |
| } |
| if (tx.green_to_red_ == 0) { |
| cur_diff -= 3; |
| } |
| if (cur_diff < best_diff) { |
| best_diff = cur_diff; |
| best_tx = tx; |
| } |
| } |
| best_diff = 1e99; |
| green_to_red = best_tx.green_to_red_; |
| for (green_to_blue = -32; green_to_blue <= 32; green_to_blue += step) { |
| for (red_to_blue = -32; red_to_blue <= 32; red_to_blue += step) { |
| int all_y; |
| int histo[256] = { 0 }; |
| Multipliers tx; |
| tx.green_to_red_ = green_to_red; |
| tx.green_to_blue_ = green_to_blue; |
| tx.red_to_blue_ = red_to_blue; |
| for (all_y = tile_y_offset; all_y < all_y_max; ++all_y) { |
| uint32_t predict; |
| int all_x; |
| int ix = all_y * xsize + tile_x_offset; |
| for (all_x = tile_x_offset; all_x < all_x_max; ++all_x, ++ix) { |
| if (SkipRepeatedPixels(argb, ix, xsize)) { |
| continue; |
| } |
| predict = TransformColor(&tx, argb[ix], 0); |
| ++histo[predict & 0xff]; // blue. |
| } |
| } |
| cur_diff = |
| PredictionCostCrossColor(&accumulated_blue_histo[0], &histo[0]); |
| if (tx.green_to_blue_ == prevX.green_to_blue_) { |
| cur_diff -= 3; // favor keeping the areas locally similar |
| } |
| if (tx.green_to_blue_ == prevY.green_to_blue_) { |
| cur_diff -= 3; // favor keeping the areas locally similar |
| } |
| if (tx.red_to_blue_ == prevX.red_to_blue_) { |
| cur_diff -= 3; // favor keeping the areas locally similar |
| } |
| if (tx.red_to_blue_ == prevY.red_to_blue_) { |
| cur_diff -= 3; // favor keeping the areas locally similar |
| } |
| if (tx.green_to_blue_ == 0) { |
| cur_diff -= 3; |
| } |
| if (tx.red_to_blue_ == 0) { |
| cur_diff -= 3; |
| } |
| if (cur_diff < best_diff) { |
| best_diff = cur_diff; |
| best_tx = tx; |
| } |
| } |
| } |
| return best_tx; |
| } |
| |
| static void CopyTileWithColorTransform(int xsize, int ysize, |
| int tile_x, int tile_y, int bits, |
| Multipliers color_transform, |
| uint32_t* const argb) { |
| int y; |
| int xscan = 1 << bits; |
| int yscan = 1 << bits; |
| tile_x <<= bits; |
| tile_y <<= bits; |
| if (xscan > xsize - tile_x) { |
| xscan = xsize - tile_x; |
| } |
| if (yscan > ysize - tile_y) { |
| yscan = ysize - tile_y; |
| } |
| yscan += tile_y; |
| for (y = tile_y; y < yscan; ++y) { |
| int ix = y * xsize + tile_x; |
| const int end_ix = ix + xscan; |
| for (; ix < end_ix; ++ix) { |
| argb[ix] = TransformColor(&color_transform, argb[ix], 0); |
| } |
| } |
| } |
| |
| void VP8LColorSpaceTransform(int width, int height, int bits, int step, |
| uint32_t* const argb, uint32_t* image) { |
| const int max_tile_size = 1 << bits; |
| int tile_xsize = VP8LSubSampleSize(width, bits); |
| int tile_ysize = VP8LSubSampleSize(height, bits); |
| int accumulated_red_histo[256] = { 0 }; |
| int accumulated_blue_histo[256] = { 0 }; |
| int tile_y; |
| int tile_x; |
| Multipliers prevX; |
| Multipliers prevY; |
| MultipliersClear(&prevY); |
| MultipliersClear(&prevX); |
| for (tile_y = 0; tile_y < tile_ysize; ++tile_y) { |
| for (tile_x = 0; tile_x < tile_xsize; ++tile_x) { |
| Multipliers color_transform; |
| int all_x_max; |
| int y; |
| const int tile_y_offset = tile_y * max_tile_size; |
| const int tile_x_offset = tile_x * max_tile_size; |
| if (tile_y != 0) { |
| ColorCodeToMultipliers(image[tile_y * tile_xsize + tile_x - 1], &prevX); |
| ColorCodeToMultipliers(image[(tile_y - 1) * tile_xsize + tile_x], |
| &prevY); |
| } else if (tile_x != 0) { |
| ColorCodeToMultipliers(image[tile_y * tile_xsize + tile_x - 1], &prevX); |
| } |
| color_transform = |
| GetBestColorTransformForTile(tile_x, tile_y, bits, |
| prevX, prevY, |
| step, width, height, |
| &accumulated_red_histo[0], |
| &accumulated_blue_histo[0], |
| argb); |
| image[tile_y * tile_xsize + tile_x] = |
| MultipliersToColorCode(&color_transform); |
| CopyTileWithColorTransform(width, height, tile_x, tile_y, bits, |
| color_transform, argb); |
| |
| // Gather accumulated histogram data. |
| all_x_max = tile_x_offset + max_tile_size; |
| if (all_x_max > width) { |
| all_x_max = width; |
| } |
| for (y = 0; y < max_tile_size; ++y) { |
| int ix; |
| int all_x; |
| int all_y = tile_y_offset + y; |
| if (all_y >= height) { |
| break; |
| } |
| ix = all_y * width + tile_x_offset; |
| for (all_x = tile_x_offset; all_x < all_x_max; ++all_x, ++ix) { |
| if (ix >= 2 && |
| argb[ix] == argb[ix - 2] && |
| argb[ix] == argb[ix - 1]) { |
| continue; // repeated pixels are handled by backward references |
| } |
| if (ix >= width + 2 && |
| argb[ix - 2] == argb[ix - width - 2] && |
| argb[ix - 1] == argb[ix - width - 1] && |
| argb[ix] == argb[ix - width]) { |
| continue; // repeated pixels are handled by backward references |
| } |
| ++accumulated_red_histo[(argb[ix] >> 16) & 0xff]; |
| ++accumulated_blue_histo[argb[ix] & 0xff]; |
| } |
| } |
| } |
| } |
| } |
| |
| // Color space inverse transform. |
| static void ColorSpaceInverseTransform(const VP8LTransform* const transform, |
| int y_start, int y_end, uint32_t* data) { |
| const int width = transform->xsize_; |
| const int mask = (1 << transform->bits_) - 1; |
| const int tiles_per_row = VP8LSubSampleSize(width, transform->bits_); |
| int y = y_start; |
| const uint32_t* pred_row = |
| transform->data_ + (y >> transform->bits_) * tiles_per_row; |
| |
| while (y < y_end) { |
| const uint32_t* pred = pred_row; |
| Multipliers m = { 0, 0, 0 }; |
| int x; |
| |
| for (x = 0; x < width; ++x) { |
| if ((x & mask) == 0) ColorCodeToMultipliers(*pred++, &m); |
| data[x] = TransformColor(&m, data[x], 1); |
| } |
| data += width; |
| ++y; |
| if ((y & mask) == 0) pred_row += tiles_per_row;; |
| } |
| } |
| |
| // Separate out pixels packed together using pixel-bundling. |
| static void ColorIndexInverseTransform( |
| const VP8LTransform* const transform, |
| int y_start, int y_end, const uint32_t* src, uint32_t* dst) { |
| int y; |
| const int bits_per_pixel = 8 >> transform->bits_; |
| const int width = transform->xsize_; |
| const uint32_t* const color_map = transform->data_; |
| if (bits_per_pixel < 8) { |
| const int pixels_per_byte = 1 << transform->bits_; |
| const int count_mask = pixels_per_byte - 1; |
| const uint32_t bit_mask = (1 << bits_per_pixel) - 1; |
| for (y = y_start; y < y_end; ++y) { |
| uint32_t packed_pixels = 0; |
| int x; |
| for (x = 0; x < width; ++x) { |
| // We need to load fresh 'packed_pixels' once every 'bytes_per_pixels' |
| // increments of x. Fortunately, pixels_per_byte is a power of 2, so |
| // can just use a mask for that, instead of decrementing a counter. |
| if ((x & count_mask) == 0) packed_pixels = ((*src++) >> 8) & 0xff; |
| *dst++ = color_map[packed_pixels & bit_mask]; |
| packed_pixels >>= bits_per_pixel; |
| } |
| } |
| } else { |
| for (y = y_start; y < y_end; ++y) { |
| int x; |
| for (x = 0; x < width; ++x) { |
| *dst++ = color_map[((*src++) >> 8) & 0xff]; |
| } |
| } |
| } |
| } |
| |
| void VP8LInverseTransform(const VP8LTransform* const transform, |
| int row_start, int row_end, |
| const uint32_t* const in, uint32_t* const out) { |
| assert(row_start < row_end); |
| assert(row_end <= transform->ysize_); |
| switch (transform->type_) { |
| case SUBTRACT_GREEN: |
| AddGreenToBlueAndRed(transform, row_start, row_end, out); |
| break; |
| case PREDICTOR_TRANSFORM: |
| PredictorInverseTransform(transform, row_start, row_end, out); |
| if (row_end != transform->ysize_) { |
| // The last predicted row in this iteration will be the top-pred row |
| // for the first row in next iteration. |
| const int width = transform->xsize_; |
| memcpy(out - width, out + (row_end - row_start - 1) * width, |
| width * sizeof(*out)); |
| } |
| break; |
| case CROSS_COLOR_TRANSFORM: |
| ColorSpaceInverseTransform(transform, row_start, row_end, out); |
| break; |
| case COLOR_INDEXING_TRANSFORM: |
| ColorIndexInverseTransform(transform, row_start, row_end, in, out); |
| break; |
| } |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Color space conversion. |
| |
| static int is_big_endian(void) { |
| static const union { |
| uint16_t w; |
| uint8_t b[2]; |
| } tmp = { 1 }; |
| return (tmp.b[0] != 1); |
| } |
| |
| static void ConvertBGRAToRGB(const uint32_t* src, |
| int num_pixels, uint8_t* dst) { |
| const uint32_t* const src_end = src + num_pixels; |
| while (src < src_end) { |
| const uint32_t argb = *src++; |
| *dst++ = (argb >> 16) & 0xff; |
| *dst++ = (argb >> 8) & 0xff; |
| *dst++ = (argb >> 0) & 0xff; |
| } |
| } |
| |
| static void ConvertBGRAToRGBA(const uint32_t* src, |
| int num_pixels, uint8_t* dst) { |
| const uint32_t* const src_end = src + num_pixels; |
| while (src < src_end) { |
| const uint32_t argb = *src++; |
| *dst++ = (argb >> 16) & 0xff; |
| *dst++ = (argb >> 8) & 0xff; |
| *dst++ = (argb >> 0) & 0xff; |
| *dst++ = (argb >> 24) & 0xff; |
| } |
| } |
| |
| static void ConvertBGRAToRGBA4444(const uint32_t* src, |
| int num_pixels, uint8_t* dst) { |
| const uint32_t* const src_end = src + num_pixels; |
| while (src < src_end) { |
| const uint32_t argb = *src++; |
| *dst++ = ((argb >> 16) & 0xf0) | ((argb >> 12) & 0xf); |
| *dst++ = ((argb >> 0) & 0xf0) | ((argb >> 28) & 0xf); |
| } |
| } |
| |
| static void ConvertBGRAToRGB565(const uint32_t* src, |
| int num_pixels, uint8_t* dst) { |
| const uint32_t* const src_end = src + num_pixels; |
| while (src < src_end) { |
| const uint32_t argb = *src++; |
| *dst++ = ((argb >> 16) & 0xf8) | ((argb >> 13) & 0x7); |
| *dst++ = ((argb >> 5) & 0xe0) | ((argb >> 3) & 0x1f); |
| } |
| } |
| |
| static void ConvertBGRAToBGR(const uint32_t* src, |
| int num_pixels, uint8_t* dst) { |
| const uint32_t* const src_end = src + num_pixels; |
| while (src < src_end) { |
| const uint32_t argb = *src++; |
| *dst++ = (argb >> 0) & 0xff; |
| *dst++ = (argb >> 8) & 0xff; |
| *dst++ = (argb >> 16) & 0xff; |
| } |
| } |
| |
| static void CopyOrSwap(const uint32_t* src, int num_pixels, uint8_t* dst, |
| int swap_on_big_endian) { |
| if (is_big_endian() == swap_on_big_endian) { |
| const uint32_t* const src_end = src + num_pixels; |
| while (src < src_end) { |
| uint32_t argb = *src++; |
| #if !defined(__BIG_ENDIAN__) && (defined(__i386__) || defined(__x86_64__)) |
| __asm__ volatile("bswap %0" : "=r"(argb) : "0"(argb)); |
| *(uint32_t*)dst = argb; |
| dst += sizeof(argb); |
| #elif !defined(__BIG_ENDIAN__) && defined(_MSC_VER) |
| argb = _byteswap_ulong(argb); |
| *(uint32_t*)dst = argb; |
| dst += sizeof(argb); |
| #else |
| *dst++ = (argb >> 24) & 0xff; |
| *dst++ = (argb >> 16) & 0xff; |
| *dst++ = (argb >> 8) & 0xff; |
| *dst++ = (argb >> 0) & 0xff; |
| #endif |
| } |
| } else { |
| memcpy(dst, src, num_pixels * sizeof(*src)); |
| } |
| } |
| |
| void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels, |
| WEBP_CSP_MODE out_colorspace, uint8_t* const rgba) { |
| switch (out_colorspace) { |
| case MODE_RGB: |
| ConvertBGRAToRGB(in_data, num_pixels, rgba); |
| break; |
| case MODE_RGBA: |
| ConvertBGRAToRGBA(in_data, num_pixels, rgba); |
| break; |
| case MODE_rgbA: |
| ConvertBGRAToRGBA(in_data, num_pixels, rgba); |
| WebPApplyAlphaMultiply(rgba, 0, num_pixels, 1, 0); |
| break; |
| case MODE_BGR: |
| ConvertBGRAToBGR(in_data, num_pixels, rgba); |
| break; |
| case MODE_BGRA: |
| CopyOrSwap(in_data, num_pixels, rgba, 1); |
| break; |
| case MODE_bgrA: |
| CopyOrSwap(in_data, num_pixels, rgba, 1); |
| WebPApplyAlphaMultiply(rgba, 0, num_pixels, 1, 0); |
| break; |
| case MODE_ARGB: |
| CopyOrSwap(in_data, num_pixels, rgba, 0); |
| break; |
| case MODE_Argb: |
| CopyOrSwap(in_data, num_pixels, rgba, 0); |
| WebPApplyAlphaMultiply(rgba, 1, num_pixels, 1, 0); |
| break; |
| case MODE_RGBA_4444: |
| ConvertBGRAToRGBA4444(in_data, num_pixels, rgba); |
| break; |
| case MODE_rgbA_4444: |
| ConvertBGRAToRGBA4444(in_data, num_pixels, rgba); |
| WebPApplyAlphaMultiply4444(rgba, num_pixels, 1, 0); |
| break; |
| case MODE_RGB_565: |
| ConvertBGRAToRGB565(in_data, num_pixels, rgba); |
| break; |
| default: |
| assert(0); // Code flow should not reach here. |
| } |
| } |
| |
| //------------------------------------------------------------------------------ |
| |
| #if defined(__cplusplus) || defined(c_plusplus) |
| } // extern "C" |
| #endif |
