diff options
Diffstat (limited to 'thirdparty/libwebp/src/enc/histogram_enc.c')
| -rw-r--r-- | thirdparty/libwebp/src/enc/histogram_enc.c | 368 |
1 files changed, 245 insertions, 123 deletions
diff --git a/thirdparty/libwebp/src/enc/histogram_enc.c b/thirdparty/libwebp/src/enc/histogram_enc.c index 4e49e0a201..8ac6fa8e02 100644 --- a/thirdparty/libwebp/src/enc/histogram_enc.c +++ b/thirdparty/libwebp/src/enc/histogram_enc.c @@ -165,7 +165,7 @@ VP8LHistogramSet* VP8LAllocateHistogramSet(int size, int cache_bits) { void VP8LHistogramSetClear(VP8LHistogramSet* const set) { int i; const int cache_bits = set->histograms[0]->palette_code_bits_; - const int size = set->size; + const int size = set->max_size; const size_t total_size = HistogramSetTotalSize(size, cache_bits); uint8_t* memory = (uint8_t*)set; @@ -180,6 +180,20 @@ void VP8LHistogramSetClear(VP8LHistogramSet* const set) { } } +// Removes the histogram 'i' from 'set' by setting it to NULL. +static void HistogramSetRemoveHistogram(VP8LHistogramSet* const set, int i, + int* const num_used) { + assert(set->histograms[i] != NULL); + set->histograms[i] = NULL; + --*num_used; + // If we remove the last valid one, shrink until the next valid one. + if (i == set->size - 1) { + while (set->size >= 1 && set->histograms[set->size - 1] == NULL) { + --set->size; + } + } +} + // ----------------------------------------------------------------------------- void VP8LHistogramAddSinglePixOrCopy(VP8LHistogram* const histo, @@ -447,7 +461,9 @@ static double HistogramAddEval(const VP8LHistogram* const a, static double HistogramAddThresh(const VP8LHistogram* const a, const VP8LHistogram* const b, double cost_threshold) { - double cost = -a->bit_cost_; + double cost; + assert(a != NULL && b != NULL); + cost = -a->bit_cost_; GetCombinedHistogramEntropy(a, b, cost_threshold, &cost); return cost; } @@ -561,14 +577,17 @@ static void HistogramBuild( } // Copies the histograms and computes its bit_cost. -static void HistogramCopyAndAnalyze( - VP8LHistogramSet* const orig_histo, VP8LHistogramSet* const image_histo) { - int i; - const int histo_size = orig_histo->size; +static const uint16_t kInvalidHistogramSymbol = (uint16_t)(-1); +static void HistogramCopyAndAnalyze(VP8LHistogramSet* const orig_histo, + VP8LHistogramSet* const image_histo, + int* const num_used, + uint16_t* const histogram_symbols) { + int i, cluster_id; + int num_used_orig = *num_used; VP8LHistogram** const orig_histograms = orig_histo->histograms; VP8LHistogram** const histograms = image_histo->histograms; - image_histo->size = 0; - for (i = 0; i < histo_size; ++i) { + assert(image_histo->max_size == orig_histo->max_size); + for (cluster_id = 0, i = 0; i < orig_histo->max_size; ++i) { VP8LHistogram* const histo = orig_histograms[i]; UpdateHistogramCost(histo); @@ -576,10 +595,19 @@ static void HistogramCopyAndAnalyze( // with no information (when they are skipped because of LZ77). if (!histo->is_used_[0] && !histo->is_used_[1] && !histo->is_used_[2] && !histo->is_used_[3] && !histo->is_used_[4]) { - continue; + // The first histogram is always used. If an histogram is empty, we set + // its id to be the same as the previous one: this will improve + // compressibility for later LZ77. + assert(i > 0); + HistogramSetRemoveHistogram(image_histo, i, num_used); + HistogramSetRemoveHistogram(orig_histo, i, &num_used_orig); + histogram_symbols[i] = kInvalidHistogramSymbol; + } else { + // Copy histograms from orig_histo[] to image_histo[]. + HistogramCopy(histo, histograms[i]); + histogram_symbols[i] = cluster_id++; + assert(cluster_id <= image_histo->max_size); } - // Copy histograms from orig_histo[] to image_histo[]. - HistogramCopy(histo, histograms[image_histo->size++]); } } @@ -596,29 +624,33 @@ static void HistogramAnalyzeEntropyBin(VP8LHistogramSet* const image_histo, // Analyze the dominant (literal, red and blue) entropy costs. for (i = 0; i < histo_size; ++i) { + if (histograms[i] == NULL) continue; UpdateDominantCostRange(histograms[i], &cost_range); } // bin-hash histograms on three of the dominant (literal, red and blue) // symbol costs and store the resulting bin_id for each histogram. for (i = 0; i < histo_size; ++i) { + // bin_map[i] is not set to a special value as its use will later be guarded + // by another (histograms[i] == NULL). + if (histograms[i] == NULL) continue; bin_map[i] = GetHistoBinIndex(histograms[i], &cost_range, low_effort); } } -// Compact image_histo[] by merging some histograms with same bin_id together if -// it's advantageous. +// Merges some histograms with same bin_id together if it's advantageous. +// Sets the remaining histograms to NULL. static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo, + int *num_used, + const uint16_t* const clusters, + uint16_t* const cluster_mappings, VP8LHistogram* cur_combo, const uint16_t* const bin_map, - int bin_map_size, int num_bins, + int num_bins, double combine_cost_factor, int low_effort) { VP8LHistogram** const histograms = image_histo->histograms; int idx; - // Work in-place: processed histograms are put at the beginning of - // image_histo[]. At the end, we just have to truncate the array. - int size = 0; struct { int16_t first; // position of the histogram that accumulates all // histograms with the same bin_id @@ -631,16 +663,19 @@ static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo, bin_info[idx].num_combine_failures = 0; } - for (idx = 0; idx < bin_map_size; ++idx) { - const int bin_id = bin_map[idx]; - const int first = bin_info[bin_id].first; - assert(size <= idx); + // By default, a cluster matches itself. + for (idx = 0; idx < *num_used; ++idx) cluster_mappings[idx] = idx; + for (idx = 0; idx < image_histo->size; ++idx) { + int bin_id, first; + if (histograms[idx] == NULL) continue; + bin_id = bin_map[idx]; + first = bin_info[bin_id].first; if (first == -1) { - // just move histogram #idx to its final position - histograms[size] = histograms[idx]; - bin_info[bin_id].first = size++; + bin_info[bin_id].first = idx; } else if (low_effort) { HistogramAdd(histograms[idx], histograms[first], histograms[first]); + HistogramSetRemoveHistogram(image_histo, idx, num_used); + cluster_mappings[clusters[idx]] = clusters[first]; } else { // try to merge #idx into #first (both share the same bin_id) const double bit_cost = histograms[idx]->bit_cost_; @@ -663,19 +698,18 @@ static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo, bin_info[bin_id].num_combine_failures >= max_combine_failures) { // move the (better) merged histogram to its final slot HistogramSwap(&cur_combo, &histograms[first]); + HistogramSetRemoveHistogram(image_histo, idx, num_used); + cluster_mappings[clusters[idx]] = clusters[first]; } else { - histograms[size++] = histograms[idx]; ++bin_info[bin_id].num_combine_failures; } - } else { - histograms[size++] = histograms[idx]; } } } - image_histo->size = size; if (low_effort) { // for low_effort case, update the final cost when everything is merged - for (idx = 0; idx < size; ++idx) { + for (idx = 0; idx < image_histo->size; ++idx) { + if (histograms[idx] == NULL) continue; UpdateHistogramCost(histograms[idx]); } } @@ -706,16 +740,9 @@ typedef struct { int max_size; } HistoQueue; -static int HistoQueueInit(HistoQueue* const histo_queue, const int max_index) { +static int HistoQueueInit(HistoQueue* const histo_queue, const int max_size) { histo_queue->size = 0; - // max_index^2 for the queue size is safe. If you look at - // HistogramCombineGreedy, and imagine that UpdateQueueFront always pushes - // data to the queue, you insert at most: - // - max_index*(max_index-1)/2 (the first two for loops) - // - max_index - 1 in the last for loop at the first iteration of the while - // loop, max_index - 2 at the second iteration ... therefore - // max_index*(max_index-1)/2 overall too - histo_queue->max_size = max_index * max_index; + histo_queue->max_size = max_size; // We allocate max_size + 1 because the last element at index "size" is // used as temporary data (and it could be up to max_size). histo_queue->queue = (HistogramPair*)WebPSafeMalloc( @@ -778,6 +805,8 @@ static double HistoQueuePush(HistoQueue* const histo_queue, const VP8LHistogram* h2; HistogramPair pair; + // Stop here if the queue is full. + if (histo_queue->size == histo_queue->max_size) return 0.; assert(threshold <= 0.); if (idx1 > idx2) { const int tmp = idx2; @@ -794,8 +823,6 @@ static double HistoQueuePush(HistoQueue* const histo_queue, // Do not even consider the pair if it does not improve the entropy. if (pair.cost_diff >= threshold) return 0.; - // We cannot add more elements than the capacity. - assert(histo_queue->size < histo_queue->max_size); histo_queue->queue[histo_queue->size++] = pair; HistoQueueUpdateHead(histo_queue, &histo_queue->queue[histo_queue->size - 1]); @@ -806,42 +833,43 @@ static double HistoQueuePush(HistoQueue* const histo_queue, // Combines histograms by continuously choosing the one with the highest cost // reduction. -static int HistogramCombineGreedy(VP8LHistogramSet* const image_histo) { +static int HistogramCombineGreedy(VP8LHistogramSet* const image_histo, + int* const num_used) { int ok = 0; - int image_histo_size = image_histo->size; + const int image_histo_size = image_histo->size; int i, j; VP8LHistogram** const histograms = image_histo->histograms; - // Indexes of remaining histograms. - int* const clusters = - (int*)WebPSafeMalloc(image_histo_size, sizeof(*clusters)); // Priority queue of histogram pairs. HistoQueue histo_queue; - if (!HistoQueueInit(&histo_queue, image_histo_size) || clusters == NULL) { + // image_histo_size^2 for the queue size is safe. If you look at + // HistogramCombineGreedy, and imagine that UpdateQueueFront always pushes + // data to the queue, you insert at most: + // - image_histo_size*(image_histo_size-1)/2 (the first two for loops) + // - image_histo_size - 1 in the last for loop at the first iteration of + // the while loop, image_histo_size - 2 at the second iteration ... + // therefore image_histo_size*(image_histo_size-1)/2 overall too + if (!HistoQueueInit(&histo_queue, image_histo_size * image_histo_size)) { goto End; } for (i = 0; i < image_histo_size; ++i) { - // Initialize clusters indexes. - clusters[i] = i; + if (image_histo->histograms[i] == NULL) continue; for (j = i + 1; j < image_histo_size; ++j) { - // Initialize positions array. + // Initialize queue. + if (image_histo->histograms[j] == NULL) continue; HistoQueuePush(&histo_queue, histograms, i, j, 0.); } } - while (image_histo_size > 1 && histo_queue.size > 0) { + while (histo_queue.size > 0) { const int idx1 = histo_queue.queue[0].idx1; const int idx2 = histo_queue.queue[0].idx2; HistogramAdd(histograms[idx2], histograms[idx1], histograms[idx1]); histograms[idx1]->bit_cost_ = histo_queue.queue[0].cost_combo; + // Remove merged histogram. - for (i = 0; i + 1 < image_histo_size; ++i) { - if (clusters[i] >= idx2) { - clusters[i] = clusters[i + 1]; - } - } - --image_histo_size; + HistogramSetRemoveHistogram(image_histo, idx2, num_used); // Remove pairs intersecting the just combined best pair. for (i = 0; i < histo_queue.size;) { @@ -856,24 +884,15 @@ static int HistogramCombineGreedy(VP8LHistogramSet* const image_histo) { } // Push new pairs formed with combined histogram to the queue. - for (i = 0; i < image_histo_size; ++i) { - if (clusters[i] != idx1) { - HistoQueuePush(&histo_queue, histograms, idx1, clusters[i], 0.); - } - } - } - // Move remaining histograms to the beginning of the array. - for (i = 0; i < image_histo_size; ++i) { - if (i != clusters[i]) { // swap the two histograms - HistogramSwap(&histograms[i], &histograms[clusters[i]]); + for (i = 0; i < image_histo->size; ++i) { + if (i == idx1 || image_histo->histograms[i] == NULL) continue; + HistoQueuePush(&histo_queue, image_histo->histograms, idx1, i, 0.); } } - image_histo->size = image_histo_size; ok = 1; End: - WebPSafeFree(clusters); HistoQueueClear(&histo_queue); return ok; } @@ -881,47 +900,69 @@ static int HistogramCombineGreedy(VP8LHistogramSet* const image_histo) { // Perform histogram aggregation using a stochastic approach. // 'do_greedy' is set to 1 if a greedy approach needs to be performed // afterwards, 0 otherwise. +static int PairComparison(const void* idx1, const void* idx2) { + // To be used with bsearch: <0 when *idx1<*idx2, >0 if >, 0 when ==. + return (*(int*) idx1 - *(int*) idx2); +} static int HistogramCombineStochastic(VP8LHistogramSet* const image_histo, - int min_cluster_size, + int* const num_used, int min_cluster_size, int* const do_greedy) { - int iter; + int j, iter; uint32_t seed = 1; int tries_with_no_success = 0; - int image_histo_size = image_histo->size; - const int outer_iters = image_histo_size; + const int outer_iters = *num_used; const int num_tries_no_success = outer_iters / 2; VP8LHistogram** const histograms = image_histo->histograms; - // Priority queue of histogram pairs. Its size of "kCostHeapSizeSqrt"^2 + // Priority queue of histogram pairs. Its size of 'kHistoQueueSize' // impacts the quality of the compression and the speed: the smaller the // faster but the worse for the compression. HistoQueue histo_queue; - const int kHistoQueueSizeSqrt = 3; + const int kHistoQueueSize = 9; int ok = 0; + // mapping from an index in image_histo with no NULL histogram to the full + // blown image_histo. + int* mappings; - if (!HistoQueueInit(&histo_queue, kHistoQueueSizeSqrt)) { + if (*num_used < min_cluster_size) { + *do_greedy = 1; + return 1; + } + + mappings = (int*) WebPSafeMalloc(*num_used, sizeof(*mappings)); + if (mappings == NULL || !HistoQueueInit(&histo_queue, kHistoQueueSize)) { goto End; } + // Fill the initial mapping. + for (j = 0, iter = 0; iter < image_histo->size; ++iter) { + if (histograms[iter] == NULL) continue; + mappings[j++] = iter; + } + assert(j == *num_used); + // Collapse similar histograms in 'image_histo'. - ++min_cluster_size; - for (iter = 0; iter < outer_iters && image_histo_size >= min_cluster_size && - ++tries_with_no_success < num_tries_no_success; + for (iter = 0; + iter < outer_iters && *num_used >= min_cluster_size && + ++tries_with_no_success < num_tries_no_success; ++iter) { + int* mapping_index; double best_cost = (histo_queue.size == 0) ? 0. : histo_queue.queue[0].cost_diff; int best_idx1 = -1, best_idx2 = 1; - int j; - const uint32_t rand_range = (image_histo_size - 1) * image_histo_size; - // image_histo_size / 2 was chosen empirically. Less means faster but worse + const uint32_t rand_range = (*num_used - 1) * (*num_used); + // (*num_used) / 2 was chosen empirically. Less means faster but worse // compression. - const int num_tries = image_histo_size / 2; + const int num_tries = (*num_used) / 2; - for (j = 0; j < num_tries; ++j) { + // Pick random samples. + for (j = 0; *num_used >= 2 && j < num_tries; ++j) { double curr_cost; // Choose two different histograms at random and try to combine them. const uint32_t tmp = MyRand(&seed) % rand_range; - const uint32_t idx1 = tmp / (image_histo_size - 1); - uint32_t idx2 = tmp % (image_histo_size - 1); + uint32_t idx1 = tmp / (*num_used - 1); + uint32_t idx2 = tmp % (*num_used - 1); if (idx2 >= idx1) ++idx2; + idx1 = mappings[idx1]; + idx2 = mappings[idx2]; // Calculate cost reduction on combination. curr_cost = @@ -934,18 +975,21 @@ static int HistogramCombineStochastic(VP8LHistogramSet* const image_histo, } if (histo_queue.size == 0) continue; - // Merge the two best histograms. + // Get the best histograms. best_idx1 = histo_queue.queue[0].idx1; best_idx2 = histo_queue.queue[0].idx2; assert(best_idx1 < best_idx2); - HistogramAddEval(histograms[best_idx1], histograms[best_idx2], - histograms[best_idx1], 0); - // Swap the best_idx2 histogram with the last one (which is now unused). - --image_histo_size; - if (best_idx2 != image_histo_size) { - HistogramSwap(&histograms[image_histo_size], &histograms[best_idx2]); - } - histograms[image_histo_size] = NULL; + // Pop best_idx2 from mappings. + mapping_index = (int*) bsearch(&best_idx2, mappings, *num_used, + sizeof(best_idx2), &PairComparison); + assert(mapping_index != NULL); + memmove(mapping_index, mapping_index + 1, sizeof(*mapping_index) * + ((*num_used) - (mapping_index - mappings) - 1)); + // Merge the histograms and remove best_idx2 from the queue. + HistogramAdd(histograms[best_idx2], histograms[best_idx1], + histograms[best_idx1]); + histograms[best_idx1]->bit_cost_ = histo_queue.queue[0].cost_combo; + HistogramSetRemoveHistogram(image_histo, best_idx2, num_used); // Parse the queue and update each pair that deals with best_idx1, // best_idx2 or image_histo_size. for (j = 0; j < histo_queue.size;) { @@ -968,12 +1012,6 @@ static int HistogramCombineStochastic(VP8LHistogramSet* const image_histo, p->idx2 = best_idx1; do_eval = 1; } - if (p->idx2 == image_histo_size) { - // No need to re-evaluate here as it does not involve a pair - // containing best_idx1 or best_idx2. - p->idx2 = best_idx2; - } - assert(p->idx2 < image_histo_size); // Make sure the index order is respected. if (p->idx1 > p->idx2) { const int tmp = p->idx2; @@ -991,15 +1029,14 @@ static int HistogramCombineStochastic(VP8LHistogramSet* const image_histo, HistoQueueUpdateHead(&histo_queue, p); ++j; } - tries_with_no_success = 0; } - image_histo->size = image_histo_size; - *do_greedy = (image_histo->size <= min_cluster_size); + *do_greedy = (*num_used <= min_cluster_size); ok = 1; End: HistoQueueClear(&histo_queue); + WebPSafeFree(mappings); return ok; } @@ -1007,23 +1044,29 @@ End: // Histogram refinement // Find the best 'out' histogram for each of the 'in' histograms. +// At call-time, 'out' contains the histograms of the clusters. // Note: we assume that out[]->bit_cost_ is already up-to-date. static void HistogramRemap(const VP8LHistogramSet* const in, - const VP8LHistogramSet* const out, + VP8LHistogramSet* const out, uint16_t* const symbols) { int i; VP8LHistogram** const in_histo = in->histograms; VP8LHistogram** const out_histo = out->histograms; - const int in_size = in->size; + const int in_size = out->max_size; const int out_size = out->size; if (out_size > 1) { for (i = 0; i < in_size; ++i) { int best_out = 0; double best_bits = MAX_COST; int k; + if (in_histo[i] == NULL) { + // Arbitrarily set to the previous value if unused to help future LZ77. + symbols[i] = symbols[i - 1]; + continue; + } for (k = 0; k < out_size; ++k) { - const double cur_bits = - HistogramAddThresh(out_histo[k], in_histo[i], best_bits); + double cur_bits; + cur_bits = HistogramAddThresh(out_histo[k], in_histo[i], best_bits); if (k == 0 || cur_bits < best_bits) { best_bits = cur_bits; best_out = k; @@ -1039,12 +1082,13 @@ static void HistogramRemap(const VP8LHistogramSet* const in, } // Recompute each out based on raw and symbols. - for (i = 0; i < out_size; ++i) { - HistogramClear(out_histo[i]); - } + VP8LHistogramSetClear(out); + out->size = out_size; for (i = 0; i < in_size; ++i) { - const int idx = symbols[i]; + int idx; + if (in_histo[i] == NULL) continue; + idx = symbols[i]; HistogramAdd(in_histo[i], out_histo[idx], out_histo[idx]); } } @@ -1060,6 +1104,70 @@ static double GetCombineCostFactor(int histo_size, int quality) { return combine_cost_factor; } +// Given a HistogramSet 'set', the mapping of clusters 'cluster_mapping' and the +// current assignment of the cells in 'symbols', merge the clusters and +// assign the smallest possible clusters values. +static void OptimizeHistogramSymbols(const VP8LHistogramSet* const set, + uint16_t* const cluster_mappings, + int num_clusters, + uint16_t* const cluster_mappings_tmp, + uint16_t* const symbols) { + int i, cluster_max; + int do_continue = 1; + // First, assign the lowest cluster to each pixel. + while (do_continue) { + do_continue = 0; + for (i = 0; i < num_clusters; ++i) { + int k; + k = cluster_mappings[i]; + while (k != cluster_mappings[k]) { + cluster_mappings[k] = cluster_mappings[cluster_mappings[k]]; + k = cluster_mappings[k]; + } + if (k != cluster_mappings[i]) { + do_continue = 1; + cluster_mappings[i] = k; + } + } + } + // Create a mapping from a cluster id to its minimal version. + cluster_max = 0; + memset(cluster_mappings_tmp, 0, + set->max_size * sizeof(*cluster_mappings_tmp)); + assert(cluster_mappings[0] == 0); + // Re-map the ids. + for (i = 0; i < set->max_size; ++i) { + int cluster; + if (symbols[i] == kInvalidHistogramSymbol) continue; + cluster = cluster_mappings[symbols[i]]; + assert(symbols[i] < num_clusters); + if (cluster > 0 && cluster_mappings_tmp[cluster] == 0) { + ++cluster_max; + cluster_mappings_tmp[cluster] = cluster_max; + } + symbols[i] = cluster_mappings_tmp[cluster]; + } + + // Make sure all cluster values are used. + cluster_max = 0; + for (i = 0; i < set->max_size; ++i) { + if (symbols[i] == kInvalidHistogramSymbol) continue; + if (symbols[i] <= cluster_max) continue; + ++cluster_max; + assert(symbols[i] == cluster_max); + } +} + +static void RemoveEmptyHistograms(VP8LHistogramSet* const image_histo) { + uint32_t size; + int i; + for (i = 0, size = 0; i < image_histo->size; ++i) { + if (image_histo->histograms[i] == NULL) continue; + image_histo->histograms[size++] = image_histo->histograms[i]; + } + image_histo->size = size; +} + int VP8LGetHistoImageSymbols(int xsize, int ysize, const VP8LBackwardRefs* const refs, int quality, int low_effort, @@ -1078,27 +1186,36 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize, // maximum quality q==100 (to preserve the compression gains at that level). const int entropy_combine_num_bins = low_effort ? NUM_PARTITIONS : BIN_SIZE; int entropy_combine; - - if (orig_histo == NULL) goto Error; + uint16_t* const map_tmp = + WebPSafeMalloc(2 * image_histo_raw_size, sizeof(map_tmp)); + uint16_t* const cluster_mappings = map_tmp + image_histo_raw_size; + int num_used = image_histo_raw_size; + if (orig_histo == NULL || map_tmp == NULL) goto Error; // Construct the histograms from backward references. HistogramBuild(xsize, histo_bits, refs, orig_histo); // Copies the histograms and computes its bit_cost. - HistogramCopyAndAnalyze(orig_histo, image_histo); + // histogram_symbols is optimized + HistogramCopyAndAnalyze(orig_histo, image_histo, &num_used, + histogram_symbols); + entropy_combine = - (image_histo->size > entropy_combine_num_bins * 2) && (quality < 100); + (num_used > entropy_combine_num_bins * 2) && (quality < 100); + if (entropy_combine) { - const int bin_map_size = image_histo->size; - // Reuse histogram_symbols storage. By definition, it's guaranteed to be ok. - uint16_t* const bin_map = histogram_symbols; + uint16_t* const bin_map = map_tmp; const double combine_cost_factor = GetCombineCostFactor(image_histo_raw_size, quality); + const uint32_t num_clusters = num_used; HistogramAnalyzeEntropyBin(image_histo, bin_map, low_effort); // Collapse histograms with similar entropy. - HistogramCombineEntropyBin(image_histo, tmp_histo, bin_map, bin_map_size, + HistogramCombineEntropyBin(image_histo, &num_used, histogram_symbols, + cluster_mappings, tmp_histo, bin_map, entropy_combine_num_bins, combine_cost_factor, low_effort); + OptimizeHistogramSymbols(image_histo, cluster_mappings, num_clusters, + map_tmp, histogram_symbols); } // Don't combine the histograms using stochastic and greedy heuristics for @@ -1108,21 +1225,26 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize, // cubic ramp between 1 and MAX_HISTO_GREEDY: const int threshold_size = (int)(1 + (x * x * x) * (MAX_HISTO_GREEDY - 1)); int do_greedy; - if (!HistogramCombineStochastic(image_histo, threshold_size, &do_greedy)) { + if (!HistogramCombineStochastic(image_histo, &num_used, threshold_size, + &do_greedy)) { goto Error; } - if (do_greedy && !HistogramCombineGreedy(image_histo)) { - goto Error; + if (do_greedy) { + RemoveEmptyHistograms(image_histo); + if (!HistogramCombineGreedy(image_histo, &num_used)) { + goto Error; + } } } - // TODO(vrabaud): Optimize HistogramRemap for low-effort compression mode. // Find the optimal map from original histograms to the final ones. + RemoveEmptyHistograms(image_histo); HistogramRemap(orig_histo, image_histo, histogram_symbols); ok = 1; Error: VP8LFreeHistogramSet(orig_histo); + WebPSafeFree(map_tmp); return ok; } |