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Added implementation for various lossless functions

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- VP8LEncAnalyze, EvalAndApplySubtractGreen, ApplyPredictFilter,
  ApplyCrossColorFilter
- Added palette handling and transform buffer management in VP8LEncodeImage()
- Add Transforms (subtract Green, Predict, cross_color) to dsp/lossless.c.

These are more-or-less copied from src/lossless code.

After this Change, will implement the EncodeImageInternal() method.

Change-Id: Idf71f803c24b3b5ae3b5079b15e019721784611d
This commit is contained in:
Vikas Arora 2012-04-10 07:00:36 +00:00 committed by James Zern
parent 32714ce3be
commit 648be3939f
6 changed files with 989 additions and 208 deletions
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689
src/dsp/lossless.c
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@ -15,12 +15,115 @@
extern "C" { extern "C" {
#endif #endif
#include <math.h>
#include <stdlib.h> #include <stdlib.h>
#include "./lossless.h" #include "./lossless.h"
#include "../dec/vp8li.h" #include "../dec/vp8li.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)]])
static const float kLogTable[] = {
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
};
double VP8LFastLog(int v) {
if (v < (int)(sizeof(kLogTable) / sizeof(kLogTable[0]))) {
return kLogTable[v];
}
return log(v);
}
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// Inverse image transforms. // Image transforms.
// In-place sum of each component with mod 256. // In-place sum of each component with mod 256.
static WEBP_INLINE void AddPixelsEq(uint32_t* a, uint32_t b) { static WEBP_INLINE void AddPixelsEq(uint32_t* a, uint32_t b) {
@ -101,61 +204,82 @@ static WEBP_INLINE uint32_t Select(uint32_t a, uint32_t b, uint32_t c) {
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// Predictors // Predictors
static void Predictor0(uint32_t* src, const uint32_t* top) { static uint32_t Predictor0(const uint32_t* const src,
const uint32_t* const top) {
(void)top; (void)top;
AddPixelsEq(src, ARGB_BLACK); (void)src;
return ARGB_BLACK;
} }
static void Predictor1(uint32_t* src, const uint32_t* top) { static uint32_t Predictor1(const uint32_t* const src,
const uint32_t* const top) {
(void)top; (void)top;
AddPixelsEq(src, src[-1]); // left return src[-1];
} }
static void Predictor2(uint32_t* src, const uint32_t* top) { static uint32_t Predictor2(const uint32_t* const src,
AddPixelsEq(src, top[0]); const uint32_t* const top) {
(void)src;
return top[0];
} }
static void Predictor3(uint32_t* src, const uint32_t* top) { static uint32_t Predictor3(const uint32_t* const src,
AddPixelsEq(src, top[1]); const uint32_t* const top) {
(void)src;
return top[1];
} }
static void Predictor4(uint32_t* src, const uint32_t* top) { static uint32_t Predictor4(const uint32_t* const src,
AddPixelsEq(src, top[-1]); const uint32_t* const top) {
(void)src;
return top[-1];
} }
static void Predictor5(uint32_t* src, const uint32_t* top) { static uint32_t Predictor5(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Average3(src[-1], top[0], top[1]); const uint32_t pred = Average3(src[-1], top[0], top[1]);
AddPixelsEq(src, pred); return pred;
} }
static void Predictor6(uint32_t* src, const uint32_t* top) { static uint32_t Predictor6(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Average2(src[-1], top[-1]); const uint32_t pred = Average2(src[-1], top[-1]);
AddPixelsEq(src, pred); return pred;
} }
static void Predictor7(uint32_t* src, const uint32_t* top) { static uint32_t Predictor7(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Average2(src[-1], top[0]); const uint32_t pred = Average2(src[-1], top[0]);
AddPixelsEq(src, pred); return pred;
} }
static void Predictor8(uint32_t* src, const uint32_t* top) { static uint32_t Predictor8(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Average2(top[-1], top[0]); const uint32_t pred = Average2(top[-1], top[0]);
AddPixelsEq(src, pred); (void)src;
return pred;
} }
static void Predictor9(uint32_t* src, const uint32_t* top) { static uint32_t Predictor9(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Average2(top[0], top[1]); const uint32_t pred = Average2(top[0], top[1]);
AddPixelsEq(src, pred); (void)src;
return pred;
} }
static void Predictor10(uint32_t* src, const uint32_t* top) { static uint32_t Predictor10(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Average4(src[-1], top[-1], top[0], top[1]); const uint32_t pred = Average4(src[-1], top[-1], top[0], top[1]);
AddPixelsEq(src, pred); return pred;
} }
static void Predictor11(uint32_t* src, const uint32_t* top) { static uint32_t Predictor11(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = Select(top[0], src[-1], top[-1]); const uint32_t pred = Select(top[0], src[-1], top[-1]);
AddPixelsEq(src, pred); return pred;
} }
static void Predictor12(uint32_t* src, const uint32_t* top) { static uint32_t Predictor12(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = ClampedAddSubtractFull(src[-1], top[0], top[-1]); const uint32_t pred = ClampedAddSubtractFull(src[-1], top[0], top[-1]);
AddPixelsEq(src, pred); return pred;
} }
static void Predictor13(uint32_t* src, const uint32_t* top) { static uint32_t Predictor13(const uint32_t* const src,
const uint32_t* const top) {
const uint32_t pred = ClampedAddSubtractHalf(src[-1], top[0], top[-1]); const uint32_t pred = ClampedAddSubtractHalf(src[-1], top[0], top[-1]);
AddPixelsEq(src, pred); return pred;
} }
typedef void (*PredictorFunc)(uint32_t* src, const uint32_t* top); typedef uint32_t (*PredictorFunc)(const uint32_t* const src,
const uint32_t* const top);
static const PredictorFunc kPredictors[16] = { static const PredictorFunc kPredictors[16] = {
Predictor0, Predictor1, Predictor2, Predictor3, Predictor0, Predictor1, Predictor2, Predictor3,
Predictor4, Predictor5, Predictor6, Predictor7, Predictor4, Predictor5, Predictor6, Predictor7,
@ -164,15 +288,201 @@ static const PredictorFunc kPredictors[16] = {
Predictor0, Predictor0 // <- padding security sentinels 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 tile_x, int tile_y, int max_tile_size,
int xsize, int ysize,
int accumulated[4][256],
const uint32_t* const argb) {
const int num_pred_modes = 14;
const int tile_y_offset = tile_y * max_tile_size;
const int tile_x_offset = tile_x * max_tile_size;
double cur_diff;
double best_diff = 1e99;
int best_mode = 0;
int mode;
int all_x_max = tile_x_offset + max_tile_size;
int all_y_max = tile_y_offset + max_tile_size;
int histo[4][256];
if (all_x_max > xsize) {
all_x_max = xsize;
}
if (all_y_max > ysize) {
all_y_max = ysize;
}
for (mode = 0; mode < num_pred_modes; ++mode) {
int all_y;
const PredictorFunc pred_func = kPredictors[mode];
memset(&histo[0][0], 0, sizeof(histo));
for (all_y = tile_y_offset; all_y < all_y_max; ++all_y) {
int all_x;
for (all_x = tile_x_offset; all_x < all_x_max; ++all_x) {
uint32_t predict;
uint32_t predict_diff;
if (all_y == 0) {
if (all_x == 0) {
predict = 0xff000000;
} else {
predict = argb[all_x - 1]; // Top Row: Pick Left Element.
}
} else if (all_x == 0) {
predict = argb[(all_y - 1) * xsize]; // First Col: Pick Top Element.
} else {
const uint32_t* src = argb + all_y * xsize + all_x;
predict = pred_func(src, src - xsize);
}
predict_diff = VP8LSubPixels(argb[all_y * xsize + all_x], 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 xsize, int ysize,
int tile_x, int tile_y, int bits, int mode,
uint32_t* const argb) {
int ymax = 1 << bits;
int xmax = 1 << bits;
int y;
const PredictorFunc pred_func = kPredictors[mode];
if (ymax > ysize - (tile_y << bits)) {
ymax = ysize - (tile_y << bits);
}
if (xmax > xsize - (tile_x << bits)) {
xmax = xsize - (tile_x << bits);
}
for (y = 0; y < ymax; ++y) {
const int all_y = (tile_y << bits) + y;
int x;
for (x = 0; x < xmax; ++x) {
const int all_x = (tile_x << bits) + x;
const int ix = all_y * xsize + all_x;
uint32_t predict;
if (all_y == 0) {
if (all_x == 0) {
predict = ARGB_BLACK;
} else {
predict = argb[ix - 1];
}
} else if (all_x == 0) {
predict = argb[ix - xsize];
} else {
predict = pred_func(argb + ix, argb + ix - xsize);
}
argb[ix] = VP8LSubPixels(argb[ix], predict);
}
}
}
void VP8LResidualImage(int width, int height, int bits,
uint32_t* const argb, uint32_t* const image) {
const int max_tile_size = 1 << bits;
const int tile_xsize = VP8LSubSampleSize(width, bits);
const int tile_ysize = VP8LSubSampleSize(height, bits);
int tile_y;
int histo[4][256];
memset(histo, 0, sizeof(histo));
for (tile_y = 0; tile_y < tile_ysize; ++tile_y) {
const int tile_y_offset = tile_y * max_tile_size;
int tile_x;
for (tile_x = 0; tile_x < tile_xsize; ++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(tile_x, tile_y, max_tile_size,
width, height, histo, argb);
image[tile_y * tile_xsize + tile_x] = 0xff000000u | (pred << 8);
CopyTileWithPrediction(width, height, tile_x, tile_y, bits, pred, 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. // Inverse prediction.
static void PredictorInverseTransform(const VP8LTransform* const transform, static void PredictorInverseTransform(const VP8LTransform* const transform,
int y_start, int y_end, uint32_t* data) { int y_start, int y_end, uint32_t* data) {
const int width = transform->xsize_; const int width = transform->xsize_;
if (y_start == 0) { // First Row follows the L (mode=1) mode. if (y_start == 0) { // First Row follows the L (mode=1) mode.
int x; int x;
Predictor0(data, NULL); uint32_t pred = Predictor0(data, NULL);
AddPixelsEq(data, pred);
for (x = 1; x < width; ++x) { for (x = 1; x < width; ++x) {
Predictor1(data + x, NULL); pred = Predictor1(data + x, NULL);
AddPixelsEq(data + x, pred);
} }
data += width; data += width;
++y_start; ++y_start;
@ -186,20 +496,24 @@ static void PredictorInverseTransform(const VP8LTransform* const transform,
transform->data_ + (y >> transform->bits_) * tiles_per_row; transform->data_ + (y >> transform->bits_) * tiles_per_row;
while (y < y_end) { while (y < y_end) {
int x;
uint32_t pred;
const uint32_t* pred_mode_src = pred_mode_base; const uint32_t* pred_mode_src = pred_mode_base;
PredictorFunc pred_func; PredictorFunc pred_func;
int x;
// First pixel follows the T (mode=2) mode. // First pixel follows the T (mode=2) mode.
Predictor2(data, data - width); pred = Predictor2(data, data - width);
AddPixelsEq(data, pred);
// .. the rest: // .. the rest:
pred_func = kPredictors[((*pred_mode_src++) >> 8) & 0xf]; pred_func = kPredictors[((*pred_mode_src++) >> 8) & 0xf];
for (x = 1; x < width; ++x) { for (x = 1; x < width; ++x) {
uint32_t pred;
if ((x & mask) == 0) { // start of tile. Read predictor function. if ((x & mask) == 0) { // start of tile. Read predictor function.
pred_func = kPredictors[((*pred_mode_src++) >> 8) & 0xf]; pred_func = kPredictors[((*pred_mode_src++) >> 8) & 0xf];
} }
pred_func(data + x, data + x - width); pred = pred_func(data + x, data + x - width);
AddPixelsEq(data + x, pred);
} }
data += width; data += width;
++y; ++y;
@ -210,8 +524,19 @@ static void PredictorInverseTransform(const VP8LTransform* const transform,
} }
} }
// Add Green to Blue and Red channels (i.e. perform the inverse transform of void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs) {
// 'Subtract Green'). 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, static void AddGreenToBlueAndRed(const VP8LTransform* const transform,
int y_start, int y_end, uint32_t* data) { int y_start, int y_end, uint32_t* data) {
const int width = transform->xsize_; const int width = transform->xsize_;
@ -233,6 +558,13 @@ typedef struct {
int red_to_blue_; int red_to_blue_;
} Multipliers; } 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, static WEBP_INLINE uint32_t ColorTransformDelta(int8_t color_pred,
int8_t color) { int8_t color) {
return (uint32_t)((int)(color_pred) * color) >> 5; return (uint32_t)((int)(color_pred) * color) >> 5;
@ -245,19 +577,276 @@ static WEBP_INLINE void ColorCodeToMultipliers(uint32_t color_code,
m->red_to_blue_ = (color_code >> 16) & 0xff; m->red_to_blue_ = (color_code >> 16) & 0xff;
} }
static WEBP_INLINE void TransformColor(const Multipliers* const m, static WEBP_INLINE uint32_t MultipliersToColorCode(Multipliers* const m) {
uint32_t* const argb) { return
const uint32_t green = *argb >> 8; 0xff000000u |
const uint32_t red = *argb >> 16; ((uint32_t)(m->red_to_blue_) << 16) |
uint32_t new_red = red; ((uint32_t)(m->green_to_blue_) << 8) |
uint32_t new_blue = *argb; m->green_to_red_;
}
new_red += ColorTransformDelta(m->green_to_red_, green); static WEBP_INLINE uint32_t TransformColor(const Multipliers* const m,
new_red &= 0xff; uint32_t argb, int inverse) {
new_blue += ColorTransformDelta(m->green_to_blue_, green); const uint32_t green = argb >> 8;
new_blue += ColorTransformDelta(m->red_to_blue_, new_red); const uint32_t red = argb >> 16;
new_blue &= 0xff; uint32_t new_red = red;
*argb = (*argb & 0xff00ff00u) | (new_red << 16) | (new_blue); 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 quality,
uint32_t* const argb, uint32_t* image) {
const int max_tile_size = 1 << bits;
const int step = (quality == 0) ? 32 : 8;
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. // Color space inverse transform.
@ -277,7 +866,7 @@ static void ColorSpaceInverseTransform(const VP8LTransform* const transform,
for (x = 0; x < width; ++x) { for (x = 0; x < width; ++x) {
if ((x & mask) == 0) ColorCodeToMultipliers(*pred++, &m); if ((x & mask) == 0) ColorCodeToMultipliers(*pred++, &m);
TransformColor(&m, data + x); data[x] = TransformColor(&m, data[x], 1);
} }
data += width; data += width;
++y; ++y;

24
src/dsp/lossless.h
View File

@ -21,7 +21,7 @@ extern "C" {
#endif #endif
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// Inverse image transforms. // Image transforms.
struct VP8LTransform; // Defined in dec/vp8li.h. struct VP8LTransform; // Defined in dec/vp8li.h.
@ -33,23 +33,41 @@ void VP8LInverseTransform(const struct VP8LTransform* const transform,
int row_start, int row_end, int row_start, int row_end,
uint32_t* const data_in, uint32_t* const data_out); uint32_t* const data_in, uint32_t* const data_out);
// Subtracts green from blue and red channels.
void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs);
void VP8LResidualImage(int width, int height, int bits,
uint32_t* const argb, uint32_t* const image);
void VP8LColorSpaceTransform(int width, int height, int bits, int quality,
uint32_t* const argb, uint32_t* image);
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// Color space conversion. // Color space conversion.
// Converts from BGRA to other color spaces. // Converts from BGRA to other color spaces.
void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels, void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels,
WEBP_CSP_MODE out_colorspace, WEBP_CSP_MODE out_colorspace,
uint8_t* const rgba); uint8_t* const rgba);
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// Misc methods. // Misc methods.
// Faster logarithm for small integers, with the property of log(0) == 0.
double VP8LFastLog(int v);
// Computes sampled size of 'size' when sampling using 'sampling bits'. // Computes sampled size of 'size' when sampling using 'sampling bits'.
static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size, static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size,
uint32_t sampling_bits) { uint32_t sampling_bits) {
return (size + (1 << sampling_bits) - 1) >> sampling_bits; return (size + (1 << sampling_bits) - 1) >> sampling_bits;
} }
// In-place difference of each component with mod 256.
static WEBP_INLINE uint32_t VP8LSubPixels(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);
return (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu);
}
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus) #if defined(__cplusplus) || defined(c_plusplus)

121
src/enc/histogram.c
View File

@ -14,107 +14,7 @@
#include "./backward_references.h" #include "./backward_references.h"
#include "./histogram.h" #include "./histogram.h"
#include "../dsp/lossless.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)]])
static const float kLogTable[] = {
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,
};
// Faster logarithm for small integers, with the property of log(0) == 0.
static WEBP_INLINE double FastLog(int v) {
if (v < (int)(sizeof(kLogTable) / sizeof(kLogTable[0]))) {
return kLogTable[v];
}
return log(v);
}
void VP8LConvertPopulationCountTableToBitEstimates( void VP8LConvertPopulationCountTableToBitEstimates(
int num_symbols, int num_symbols,
@ -176,21 +76,6 @@ void VP8LHistogramCreate(VP8LHistogram* const p,
} }
} }
double VP8LShannonEntropy(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] * FastLog(array[i]);
}
}
retval -= sum * FastLog(sum);
retval *= -1.4426950408889634; // 1.0 / -FastLog(2);
return retval;
}
static double BitsEntropy(const int* const array, int n) { static double BitsEntropy(const int* const array, int n) {
double retval = 0; double retval = 0;
int sum = 0; int sum = 0;
@ -202,13 +87,13 @@ static double BitsEntropy(const int* const array, int n) {
if (array[i] != 0) { if (array[i] != 0) {
sum += array[i]; sum += array[i];
++nonzeros; ++nonzeros;
retval += array[i] * FastLog(array[i]); retval += array[i] * VP8LFastLog(array[i]);
if (max_val < array[i]) { if (max_val < array[i]) {
max_val = array[i]; max_val = array[i];
} }
} }
} }
retval -= sum * FastLog(sum); retval -= sum * VP8LFastLog(sum);
retval *= -1.4426950408889634; // 1.0 / -Log(2); retval *= -1.4426950408889634; // 1.0 / -Log(2);
mix = 0.627; mix = 0.627;
if (nonzeros < 5) { if (nonzeros < 5) {

4
src/enc/histogram.h
View File

@ -47,7 +47,7 @@ static WEBP_INLINE void VP8LHistogramClear(VP8LHistogram* const p) {
} }
static WEBP_INLINE void VP8LHistogramInit(VP8LHistogram* const p, static WEBP_INLINE void VP8LHistogramInit(VP8LHistogram* const p,
int palette_code_bits) { int palette_code_bits) {
p->palette_code_bits_ = palette_code_bits; p->palette_code_bits_ = palette_code_bits;
VP8LHistogramClear(p); VP8LHistogramClear(p);
} }
@ -118,8 +118,6 @@ static WEBP_INLINE int VP8LHistogramNumCodes(const VP8LHistogram* const p) {
void VP8LConvertPopulationCountTableToBitEstimates( void VP8LConvertPopulationCountTableToBitEstimates(
int n, const int* const population_counts, double* const output); int n, const int* const population_counts, double* const output);
double VP8LShannonEntropy(const int* const array, int n);
// Build a 2d image of histograms, subresolutioned by (1 << histobits) to // Build a 2d image of histograms, subresolutioned by (1 << histobits) to
// the original image. // the original image.
int VP8LHistogramBuildImage(int xsize, int ysize, int VP8LHistogramBuildImage(int xsize, int ysize,

339
src/enc/vp8l.c
View File

@ -13,8 +13,11 @@
#include <assert.h> #include <assert.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include "./backward_references.h"
#include "./vp8enci.h" #include "./vp8enci.h"
#include "./vp8li.h" #include "./vp8li.h"
#include "../dsp/lossless.h"
#include "../utils/bit_writer.h" #include "../utils/bit_writer.h"
#if defined(__cplusplus) || defined(c_plusplus) #if defined(__cplusplus) || defined(c_plusplus)
@ -23,37 +26,223 @@ extern "C" {
static const uint32_t kImageSizeBits = 14; static const uint32_t kImageSizeBits = 14;
static int Uint32Order(const void* p1, const void* p2) {
const uint32_t a = *(const uint32_t*)p1;
const uint32_t b = *(const uint32_t*)p2;
if (a < b) {
return -1;
}
if (a == b) {
return 0;
}
return 1;
}
static int CreatePalette256(const uint32_t* const argb, int num_pix,
uint32_t* const palette, int* const palette_size) {
int i, key;
int current_size = 0;
uint8_t in_use[MAX_PALETTE_SIZE * 4];
uint32_t colors[MAX_PALETTE_SIZE * 4];
static const uint32_t kHashMul = 0x1e35a7bd;
memset(in_use, 0, sizeof(in_use));
key = (kHashMul * argb[0]) >> PALETTE_KEY_RIGHT_SHIFT;
colors[key] = argb[0];
in_use[key] = 1;
++current_size;
for (i = 1; i < num_pix; ++i) {
if (argb[i] == argb[i - 1]) {
continue;
}
key = (kHashMul * argb[i]) >> PALETTE_KEY_RIGHT_SHIFT;
while (1) {
if (!in_use[key]) {
colors[key] = argb[i];
in_use[key] = 1;
++current_size;
if (current_size > MAX_PALETTE_SIZE) {
return 0;
}
break;
} else if (colors[key] == argb[i]) {
// The color is already there.
break;
} else {
// Some other color sits there.
// Do linear conflict resolution.
++key;
key &= 0x3ff; // key for 1K buffer.
}
}
}
*palette_size = 0;
for (i = 0; i < (int)sizeof(in_use); ++i) {
if (in_use[i]) {
palette[*palette_size] = colors[i];
++(*palette_size);
}
}
qsort(palette, *palette_size, sizeof(*palette), Uint32Order);
return 1;
}
static int AnalyzeEntropy(const uint32_t const *argb, int xsize, int ysize,
int* nonpredicted_bits, int* predicted_bits) {
int i;
uint32_t pix_diff;
VP8LHistogram* nonpredicted = NULL;
VP8LHistogram* predicted = (VP8LHistogram*)malloc(2 * sizeof(*predicted));
if (predicted == NULL) return 0;
nonpredicted = predicted + sizeof(*predicted);
VP8LHistogramInit(predicted, 0);
VP8LHistogramInit(nonpredicted, 0);
for (i = 1; i < xsize * ysize; ++i) {
if ((argb[i] == argb[i - 1]) ||
(i >= xsize && argb[i] == argb[i - xsize])) {
continue;
}
VP8LHistogramAddSinglePixOrCopy(nonpredicted,
PixOrCopyCreateLiteral(argb[i]));
pix_diff = VP8LSubPixels(argb[i], argb[i - 1]);
VP8LHistogramAddSinglePixOrCopy(predicted,
PixOrCopyCreateLiteral(pix_diff));
}
*nonpredicted_bits = (int)VP8LHistogramEstimateBitsBulk(nonpredicted);
*predicted_bits = (int)VP8LHistogramEstimateBitsBulk(predicted);
free(predicted);
return 1;
}
static int VP8LEncAnalyze(VP8LEncoder* const enc) { static int VP8LEncAnalyze(VP8LEncoder* const enc) {
(void)enc; const WebPPicture* const pic = enc->pic_;
int non_pred_entropy, pred_entropy;
int is_photograph = 0;
assert(pic && pic->argb);
if (!AnalyzeEntropy(pic->argb, pic->width, pic->height,
&non_pred_entropy, &pred_entropy)) {
return 0;
}
is_photograph =
pred_entropy < (non_pred_entropy - (non_pred_entropy >> 3));
if (is_photograph) {
enc->use_predict_ = 1;
enc->use_cross_color_ = 1;
}
enc->use_palette_ = CreatePalette256(pic->argb, pic->width * pic->height,
enc->palette_, &enc->palette_size_);
return 1; return 1;
} }
static int EncodeImageInternal(VP8LEncoder* const enc) { // Bundles multiple (2, 4 or 8) pixels into a single pixel.
(void)enc; // Returns the new xsize.
static void BundleColorMap(const uint32_t* const argb,
int width, int height, int xbits,
uint32_t* bundled_argb, int xs) {
int x, y;
const int bit_depth = 1 << (3 - xbits);
uint32_t code = 0;
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
const int xsub = x & ((1 << xbits) - 1);
if (xsub == 0) {
code = 0;
}
code |= (argb[y * width + x] & 0xff00) << (bit_depth * xsub);
bundled_argb[y * xs + (x >> xbits)] = 0xff000000 | code;
}
}
}
static int EncodeImageInternal(VP8LBitWriter* const bw,
const uint32_t* const argb,
int width, int height, int quality,
int cache_bits, int histogram_bits) {
(void)bw;
(void)argb;
(void)width;
(void)height;
(void)quality;
(void)cache_bits;
(void)histogram_bits;
return 1; return 1;
} }
static int CreatePalette(VP8LEncoder* const enc) { static int EvalAndApplySubtractGreen(VP8LBitWriter* const bw,
(void)enc; VP8LEncoder* const enc,
int width, int height) {
int i;
VP8LHistogram* before = NULL;
// Check if it would be a good idea to subtract green from red and blue.
VP8LHistogram* after = (VP8LHistogram*)malloc(2 * sizeof(*after));
if (after == NULL) return 0;
before = after + sizeof(*after);
VP8LHistogramInit(before, 1);
VP8LHistogramInit(after, 1);
for (i = 0; i < width * height; ++i) {
// We only impact entropy in red and blue components, don't bother
// to look at others.
const uint32_t c = enc->argb_[i];
const int green = (c >> 8) & 0xff;
++(before->red_[(c >> 16) & 0xff]);
++(before->blue_[c & 0xff]);
++(after->red_[((c >> 16) - green) & 0xff]);
++(after->blue_[(c - green) & 0xff]);
}
// Check if subtracting green yields low entropy.
if (VP8LHistogramEstimateBits(after) < VP8LHistogramEstimateBits(before)) {
VP8LWriteBits(bw, 1, 1);
VP8LWriteBits(bw, 2, 2);
VP8LSubtractGreenFromBlueAndRed(enc->argb_, width * height);
}
free(after);
return 1; return 1;
} }
static void EvalSubtractGreen(VP8LEncoder* const enc) { static int ApplyPredictFilter(VP8LBitWriter* const bw,
(void)enc; VP8LEncoder* const enc,
} int width, int height, int quality) {
const int pred_bits = enc->transform_bits_;
const int transform_width = VP8LSubSampleSize(width, pred_bits);
const int transform_height = VP8LSubSampleSize(height, pred_bits);
static int ApplyPredictFilter(VP8LEncoder* const enc) { VP8LResidualImage(width, height, pred_bits, enc->argb_, enc->transform_data_);
(void)enc; VP8LWriteBits(bw, 1, 1);
VP8LWriteBits(bw, 2, 0);
VP8LWriteBits(bw, 4, pred_bits);
if (!EncodeImageInternal(bw, enc->transform_data_,
transform_width, transform_height, quality, 0, 0)) {
return 0;
}
return 1; return 1;
} }
static int ApplyCrossColorFilter(VP8LEncoder* const enc) { static int ApplyCrossColorFilter(VP8LBitWriter* const bw,
(void)enc; VP8LEncoder* const enc,
return 1; int width, int height, int quality) {
} const int ccolor_transform_bits = enc->transform_bits_;
const int transform_width = VP8LSubSampleSize(width, ccolor_transform_bits);
const int transform_height = VP8LSubSampleSize(height, ccolor_transform_bits);
static void EvalColorCache(VP8LEncoder* const enc) { VP8LColorSpaceTransform(width, height, ccolor_transform_bits, quality,
(void)enc; enc->argb_, enc->transform_data_);
VP8LWriteBits(bw, 1, 1);
VP8LWriteBits(bw, 2, 1);
VP8LWriteBits(bw, 4, ccolor_transform_bits);
if (!EncodeImageInternal(bw, enc->transform_data_,
transform_width, transform_height, quality, 0, 0)) {
return 0;
}
return 1;
} }
static void PutLE32(uint8_t* const data, uint32_t val) { static void PutLE32(uint8_t* const data, uint32_t val) {
@ -125,10 +314,15 @@ static VP8LEncoder* InitVP8LEncoder(const WebPConfig* const config,
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY); WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
return NULL; return NULL;
} }
memset(enc, 0, sizeof(*enc));
enc->pic_ = picture; enc->pic_ = picture;
enc->use_lz77_ = 1; enc->use_lz77_ = 1;
enc->palette_bits_ = 7; enc->palette_bits_ = 7;
enc->argb_ = NULL;
enc->width_ = picture->width;
// TODO: Use config.quality to initialize histo_bits_ and transform_bits_. // TODO: Use config.quality to initialize histo_bits_ and transform_bits_.
enc->histo_bits_ = 4; enc->histo_bits_ = 4;
enc->transform_bits_ = 4; enc->transform_bits_ = 4;
@ -150,9 +344,32 @@ static void DeleteVP8LEncoder(VP8LEncoder* enc) {
free(enc); free(enc);
} }
static WebPEncodingError AllocateEncodeBuffer(VP8LEncoder* const enc,
int height, int width) {
WebPEncodingError err = VP8_ENC_OK;
const size_t image_size = height * width;
const size_t transform_data_size =
VP8LSubSampleSize(height, enc->transform_bits_) *
VP8LSubSampleSize(width, enc->transform_bits_);
const size_t total_size = image_size + transform_data_size;
enc->argb_ = (uint32_t*)malloc(total_size * sizeof(*enc->argb_));
if (enc->argb_ == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
enc->transform_data_ = enc->argb_ + image_size;
Error:
return err;
}
int VP8LEncodeImage(const WebPConfig* const config, int VP8LEncodeImage(const WebPConfig* const config,
WebPPicture* const picture) { WebPPicture* const picture) {
int i;
int ok = 0; int ok = 0;
int use_color_cache = 1;
int cache_bits = 7;
int width, height, quality;
VP8LEncoder* enc = NULL; VP8LEncoder* enc = NULL;
WebPEncodingError err = VP8_ENC_OK; WebPEncodingError err = VP8_ENC_OK;
VP8LBitWriter bw; VP8LBitWriter bw;
@ -169,42 +386,110 @@ int VP8LEncodeImage(const WebPConfig* const config,
err = VP8_ENC_ERROR_NULL_PARAMETER; err = VP8_ENC_ERROR_NULL_PARAMETER;
goto Error; goto Error;
} }
width = picture->width;
height = picture->height;
quality = config->quality;
VP8LBitWriterInit(&bw, (picture->width * picture->height) >> 1); VP8LBitWriterInit(&bw, (width * height) >> 1);
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Analyze image (entropy, num_palettes etc) // Analyze image (entropy, num_palettes etc)
if (!VP8LEncAnalyze(enc)) goto Error; if (!VP8LEncAnalyze(enc)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
if (enc->use_palette_) { goto Error;
CreatePalette(enc);
} }
// Write image size. // Write image size.
WriteImageSize(enc, &bw); WriteImageSize(enc, &bw);
if (enc->use_palette_) {
uint32_t* argb = picture->argb;
const uint32_t* const palette = enc->palette_;
const int palette_size = enc->palette_size_;
uint32_t argb_palette[MAX_PALETTE_SIZE];
for (i = 0; i < width * height; ++i) {
int k;
for (k = 0; k < palette_size; ++k) {
if (argb[i] == palette[k]) {
argb_palette[i] = 0xff000000 | (k << 8);
break;
}
}
}
VP8LWriteBits(&bw, 1, 1);
VP8LWriteBits(&bw, 2, 3);
VP8LWriteBits(&bw, 8, palette_size - 1);
for (i = palette_size - 1; i >= 1; --i) {
argb_palette[i] = VP8LSubPixels(palette[i], palette[i - 1]);
}
if (!EncodeImageInternal(&bw, argb_palette, palette_size, 1, quality,
0, 0)) {
goto Error;
}
use_color_cache = 0;
if (palette_size <= 16) {
int xbits = 1;
if (palette_size <= 2) {
xbits = 3;
} else if (palette_size <= 4) {
xbits = 2;
}
// Image can be packed (multiple pixels per uint32).
enc->width_ = VP8LSubSampleSize(width, xbits);
err = AllocateEncodeBuffer(enc, height, enc->width_);
if (err != VP8_ENC_OK) goto Error;
BundleColorMap(argb, width, height, xbits, enc->argb_, enc->width_);
}
}
// In case image is not packed.
if (enc->argb_ == NULL) {
const size_t image_size = height * enc->width_;
err = AllocateEncodeBuffer(enc, height, enc->width_);
if (err != VP8_ENC_OK) goto Error;
memcpy(enc->argb_, picture->argb, image_size * sizeof(*enc->argb_));
}
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Apply transforms and write transform data. // Apply transforms and write transform data.
EvalSubtractGreen(enc); if (!EvalAndApplySubtractGreen(&bw, enc, enc->width_, height)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
if (enc->use_predict_) { if (enc->use_predict_) {
if (!ApplyPredictFilter(enc)) goto Error; if (!ApplyPredictFilter(&bw, enc, enc->width_, height, quality)) {
err = VP8_ENC_ERROR_INVALID_CONFIGURATION;
goto Error;
}
} }
if (enc->use_cross_color_) { if (enc->use_cross_color_) {
if (!ApplyCrossColorFilter(enc)) goto Error; if (!ApplyCrossColorFilter(&bw, enc, enc->width_, height, quality)) {
err = VP8_ENC_ERROR_INVALID_CONFIGURATION;
goto Error;
}
} }
if (enc->use_color_cache) { if (use_color_cache) {
EvalColorCache(enc); if (quality > 25) {
if (!VP8LCalculateEstimateForPaletteSize(enc->argb_, enc->width_, height,
&cache_bits)) {
err = VP8_ENC_ERROR_INVALID_CONFIGURATION;
goto Error;
}
}
} }
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Encode and write the transformed image. // Encode and write the transformed image.
ok = EncodeImageInternal(enc); ok = EncodeImageInternal(&bw, enc->argb_, enc->width_, height,
quality, cache_bits, enc->histo_bits_);
if (!ok) goto Error; if (!ok) goto Error;
err = WriteImage(enc, &bw); err = WriteImage(enc, &bw);

20
src/enc/vp8li.h
View File

@ -12,6 +12,7 @@
#ifndef WEBP_ENC_VP8LI_H_ #ifndef WEBP_ENC_VP8LI_H_
#define WEBP_ENC_VP8LI_H_ #define WEBP_ENC_VP8LI_H_
#include "./histogram.h"
#include "../webp/encode.h" #include "../webp/encode.h"
#include "../utils/bit_writer.h" #include "../utils/bit_writer.h"
@ -27,9 +28,16 @@ extern "C" {
#define SIGNATURE_SIZE 1 #define SIGNATURE_SIZE 1
#define LOSSLESS_MAGIC_BYTE 0x64 #define LOSSLESS_MAGIC_BYTE 0x64
#define MAX_PALETTE_SIZE 256
#define PALETTE_KEY_RIGHT_SHIFT 22 // Key for 1K buffer.
typedef struct { typedef struct {
const WebPConfig* config_; // user configuration and parameters const WebPConfig* config_; // user configuration and parameters
WebPPicture* pic_; // input / output picture WebPPicture* pic_; // input picture.
uint32_t* argb_; // Transformed argb image data.
uint32_t* transform_data_; // Scratch memory for transform data.
int width_; // Packed image width.
// Encoding parameters derived from quality parameter. // Encoding parameters derived from quality parameter.
int use_lz77_; int use_lz77_;
@ -38,13 +46,11 @@ typedef struct {
int transform_bits_; int transform_bits_;
// Encoding parameters derived from image characteristics. // Encoding parameters derived from image characteristics.
int predicted_bits_;
int non_predicted_bits_;
int use_palette_;
int num_palette_colors;
int use_predict_;
int use_cross_color_; int use_cross_color_;
int use_color_cache; int use_predict_;
int use_palette_;
int palette_size_;
uint32_t palette_[MAX_PALETTE_SIZE];
} VP8LEncoder; } VP8LEncoder;
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------