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optimization of cv::CLAHE (~3x)

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This commit is contained in:
Ilya Lavrenov 2014-09-30 11:32:57 -07:00
parent af6a64d76b
commit 6f05a250be
1 changed files with 41 additions and 24 deletions
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65
modules/imgproc/src/clahe.cpp
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@ -233,6 +233,31 @@ namespace
CLAHE_Interpolation_Body(const cv::Mat& src, const cv::Mat& dst, const cv::Mat& lut, const cv::Size& tileSize, const int& tilesX, const int& tilesY) :
src_(src), dst_(dst), lut_(lut), tileSize_(tileSize), tilesX_(tilesX), tilesY_(tilesY)
{
buf.allocate(src.cols << 2);
ind1_p = (int *)buf;
ind2_p = ind1_p + src.cols;
xa_p = (float *)(ind2_p + src.cols);
xa1_p = xa_p + src.cols;
int lut_step = static_cast<int>(lut_.step / sizeof(T));
float inv_tw = 1.0f / tileSize_.width;
for (int x = 0; x < src.cols; ++x)
{
float txf = x * inv_tw - 0.5f;
int tx1 = cvFloor(txf);
int tx2 = tx1 + 1;
xa_p[x] = txf - tx1;
xa1_p[x] = 1.0f - xa_p[x];
tx1 = std::max(tx1, 0);
tx2 = std::min(tx2, tilesX_ - 1);
ind1_p[x] = tx1 * lut_step;
ind2_p[x] = tx2 * lut_step;
}
}
void operator ()(const cv::Range& range) const;
@ -245,24 +270,28 @@ namespace
cv::Size tileSize_;
int tilesX_;
int tilesY_;
cv::AutoBuffer<int> buf;
int * ind1_p, * ind2_p;
float * xa_p, * xa1_p;
};
template <class T>
void CLAHE_Interpolation_Body<T>::operator ()(const cv::Range& range) const
{
const size_t lut_step = lut_.step / sizeof(T);
float inv_th = 1.0f / tileSize_.height;
for (int y = range.start; y < range.end; ++y)
{
const T* srcRow = src_.ptr<T>(y);
T* dstRow = dst_.ptr<T>(y);
const float tyf = (static_cast<float>(y) / tileSize_.height) - 0.5f;
float tyf = y * inv_th - 0.5f;
int ty1 = cvFloor(tyf);
int ty2 = ty1 + 1;
const float ya = tyf - ty1;
float ya = tyf - ty1, ya1 = 1.0f - ya;
ty1 = std::max(ty1, 0);
ty2 = std::min(ty2, tilesY_ - 1);
@ -272,27 +301,13 @@ namespace
for (int x = 0; x < src_.cols; ++x)
{
const float txf = (static_cast<float>(x) / tileSize_.width) - 0.5f;
int srcVal = srcRow[x];
int tx1 = cvFloor(txf);
int tx2 = tx1 + 1;
int ind1 = ind1_p[x] + srcVal;
int ind2 = ind2_p[x] + srcVal;
const float xa = txf - tx1;
tx1 = std::max(tx1, 0);
tx2 = std::min(tx2, tilesX_ - 1);
const int srcVal = srcRow[x];
const size_t ind1 = tx1 * lut_step + srcVal;
const size_t ind2 = tx2 * lut_step + srcVal;
float res = 0;
res += lutPlane1[ind1] * ((1.0f - xa) * (1.0f - ya));
res += lutPlane1[ind2] * ((xa) * (1.0f - ya));
res += lutPlane2[ind1] * ((1.0f - xa) * (ya));
res += lutPlane2[ind2] * ((xa) * (ya));
float res = (lutPlane1[ind1] * xa1_p[x] + lutPlane1[ind2] * xa_p[x]) * ya1 +
(lutPlane2[ind1] * xa1_p[x] + lutPlane2[ind2] * xa_p[x]) * ya;
dstRow[x] = cv::saturate_cast<T>(res);
}
@ -403,7 +418,9 @@ namespace
calcLutBody = cv::makePtr<CLAHE_CalcLut_Body<uchar, 256, 0> >(srcForLut, lut_, tileSize, tilesX_, clipLimit, lutScale);
else if (_src.type() == CV_16UC1)
calcLutBody = cv::makePtr<CLAHE_CalcLut_Body<ushort, 4096, 4> >(srcForLut, lut_, tileSize, tilesX_, clipLimit, lutScale);
CV_Assert(!calcLutBody.empty());
else
CV_Error( CV_StsBadArg, "Unsupported type" );
cv::parallel_for_(cv::Range(0, tilesX_ * tilesY_), *calcLutBody);
cv::Ptr<cv::ParallelLoopBody> interpolationBody;
@ -411,7 +428,7 @@ namespace
interpolationBody = cv::makePtr<CLAHE_Interpolation_Body<uchar> >(src, dst, lut_, tileSize, tilesX_, tilesY_);
else if (_src.type() == CV_16UC1)
interpolationBody = cv::makePtr<CLAHE_Interpolation_Body<ushort> >(src, dst, lut_, tileSize, tilesX_, tilesY_);
CV_Assert(!interpolationBody.empty());
cv::parallel_for_(cv::Range(0, src.rows), *interpolationBody);
}