potok/opencv
1
0
Fork 0
mirror of https://github.com/opencv/opencv.git synced 2026-07-29 15:23:05 +04:00
Code Packages Releases Wiki Activity

Speed up first BGR2Lab and BGR2Luv call by building the color LUT faster

Browse Source 
The first conversion to Lab or Luv lazily builds a softfloat lookup table, and that build was doing about 108000 software emulated pow calls plus a fully serial 33x33x33 cube loop. This memoizes applyGamma over the 33 grid values and runs the cube loop with parallel_for_, cutting the first call from around 110 ms to around 25 ms on my machine. The per point computation is unchanged so the tables stay bit exact.
This commit is contained in:
Samaresh Kumar Singh
2026-06-06 16:36:07 -05:00
parent 7224bced8b
commit c936dcaef7
1 changed files with 12 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
modules/imgproc/src/color_lab.cpp
+12 -8
View File
@@ -1160,20 +1160,23 @@ static LABLUVLUT_s16_t initLUTforLABLUVs16(const softfloat & un, const softfloat
AutoBuffer<int16_t> RGB2Labprev(LAB_LUT_DIM*LAB_LUT_DIM*LAB_LUT_DIM*3);
AutoBuffer<int16_t> RGB2Luvprev(LAB_LUT_DIM*LAB_LUT_DIM*LAB_LUT_DIM*3);
for(int p = 0; p < LAB_LUT_DIM; p++)
softfloat gammaTab[LAB_LUT_DIM];
for(int n = 0; n < LAB_LUT_DIM; n++)
gammaTab[n] = applyGamma(softfloat(n)/lld);
cv::parallel_for_(cv::Range(0, LAB_LUT_DIM), [&](const cv::Range& prange)
{
for(int p = prange.start; p < prange.end; p++)
{
for(int q = 0; q < LAB_LUT_DIM; q++)
{
for(int r = 0; r < LAB_LUT_DIM; r++)
{
int idx = p*3 + q*LAB_LUT_DIM*3 + r*LAB_LUT_DIM*LAB_LUT_DIM*3;
softfloat R = softfloat(p)/lld;
softfloat G = softfloat(q)/lld;
softfloat B = softfloat(r)/lld;
R = applyGamma(R);
G = applyGamma(G);
B = applyGamma(B);
softfloat R = gammaTab[p];
softfloat G = gammaTab[q];
softfloat B = gammaTab[r];
//RGB 2 Lab LUT building
{
@@ -1214,6 +1217,7 @@ static LABLUVLUT_s16_t initLUTforLABLUVs16(const softfloat & un, const softfloat
}
}
}
});
int16_t *RGB2LabLUT_s16 = cv::allocSingleton<int16_t>(LAB_LUT_DIM*LAB_LUT_DIM*LAB_LUT_DIM*3*8);
int16_t *RGB2LuvLUT_s16 = cv::allocSingleton<int16_t>(LAB_LUT_DIM*LAB_LUT_DIM*LAB_LUT_DIM*3*8);