ColorHistogram ColorHistogram::ScaleHistogram(const vector<float>& gain) const {
const ColorHistogramIndexLUT& lut =
ColorHistogramIndexLUTFactory::Instance().GetLUT(
lum_bins_, color_bins_, color_bins_);
ColorHistogram result = EmptyCopy();
if (!IsSparse()) {
for (int i = 0; i < total_bins_; ++i) {
const float value = bins_[i];
if (value) {
const std::tuple<int, int, int>& idx_3d = lut.Ind2Sub(i);
const float bin_lum = std::min(lum_bins_ - 1.f, std::get<0>(idx_3d) * gain[0]);
const float bin_col1 = std::min(color_bins_ - 1.f, std::get<1>(idx_3d) * gain[1]);
const float bin_col2 = std::min(color_bins_ - 1.f, std::get<2>(idx_3d) * gain[2]);
result.AddValueInterpolated(bin_lum, bin_col1, bin_col2, value);
}
}
} else {
for (const auto& bin : sparse_bins_) {
const std::tuple<int, int, int>& idx_3d = lut.Ind2Sub(bin.first);
const float bin_lum = std::min(lum_bins_ - 1.f, std::get<0>(idx_3d) * gain[0]);
const float bin_col1 = std::min(color_bins_ - 1.f, std::get<1>(idx_3d) * gain[1]);
const float bin_col2 = std::min(color_bins_ - 1.f, std::get<2>(idx_3d) * gain[2]);
result.AddValueInterpolated(bin_lum, bin_col1, bin_col2, bin.second);
}
}
DCHECK_LT(fabs(WeightSum() - result.WeightSum()), 1e-3f);
return result;
}
HuffmanCode::WeightSum HuffmanCode::build(const std::vector<HuffmanCode::WeightTp>& W) {
if (W.empty()) {
output_code.clear();
return WeightSum();
}
unsigned int n = W.size();
typedef std::pair<WeightTp, unsigned int> PP;
std::priority_queue<PP, std::vector<PP>, std::greater<PP> > pq;
unsigned int i = 0;
for (std::vector<WeightTp>::const_iterator it = W.begin(); it != W.end(); ++it)
pq.push(std::make_pair(*it, i++));
std::vector<unsigned int> parent(W.size());
parent.reserve(W.size()*2 - 1);
assert(!pq.empty());
while (true) {
PP t1 = pq.top();
pq.pop();
if (pq.empty()) break;
PP t2 = pq.top();
pq.pop();
parent.push_back(0);
unsigned int newid = parent.size() - 1;
parent[t1.second] = newid;
parent[t2.second] = newid;
pq.push(std::make_pair(t1.first + t2.first, newid));
}
assert(pq.empty());
// compute code length
std::vector<uint16_t> L(parent.size());
L[L.size() - 1] = 0;
WeightSum total = 0;
for (int i = (int)L.size()-2; i >= 0; i--) {
L[i] = 1 + L[parent[i]];
if ((unsigned int) i < n) total += ((WeightSum)W[i]) * L[i];
}
loadCode(W.size(), L);
return total;
}
