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Merge pull request #18001 from Yosshi999:sift-8bit-descr

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* 8-bit SIFT descriptors

* use clearer parameter

* update docs

* propagate type info

* overload function for avoiding ABI-break

* bugfix: some values are undefined when CV_SIMD is absent
This commit is contained in:
Yosshi999
2020-08-17 19:28:44 +09:00
committed by GitHub
parent b34234ac14
commit 1834eed809
4 changed files with 158 additions and 42 deletions
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modules/features2d/src/sift.simd.hpp
+75 -32
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@@ -150,7 +150,7 @@ void findScaleSpaceExtrema(
void calcSIFTDescriptor(
const Mat& img, Point2f ptf, float ori, float scl,
int d, int n, float* dst
int d, int n, Mat& dst, int row
);
@@ -555,7 +555,7 @@ void findScaleSpaceExtrema(
void calcSIFTDescriptor(
const Mat& img, Point2f ptf, float ori, float scl,
int d, int n, float* dst
int d, int n, Mat& dstMat, int row
)
{
CV_TRACE_FUNCTION();
@@ -575,9 +575,18 @@ void calcSIFTDescriptor(
int i, j, k, len = (radius*2+1)*(radius*2+1), histlen = (d+2)*(d+2)*(n+2);
int rows = img.rows, cols = img.cols;
AutoBuffer<float> buf(len*6 + histlen);
float *X = buf.data(), *Y = X + len, *Mag = Y, *Ori = Mag + len, *W = Ori + len;
float *RBin = W + len, *CBin = RBin + len, *hist = CBin + len;
cv::utils::BufferArea area;
float *X = 0, *Y = 0, *Mag, *Ori = 0, *W = 0, *RBin = 0, *CBin = 0, *hist = 0, *rawDst = 0;
area.allocate(X, len, CV_SIMD_WIDTH);
area.allocate(Y, len, CV_SIMD_WIDTH);
area.allocate(Ori, len, CV_SIMD_WIDTH);
area.allocate(W, len, CV_SIMD_WIDTH);
area.allocate(RBin, len, CV_SIMD_WIDTH);
area.allocate(CBin, len, CV_SIMD_WIDTH);
area.allocate(hist, histlen, CV_SIMD_WIDTH);
area.allocate(rawDst, len, CV_SIMD_WIDTH);
area.commit();
Mag = Y;
for( i = 0; i < d+2; i++ )
{
@@ -628,10 +637,10 @@ void calcSIFTDescriptor(
const v_int32 __n_plus_2 = vx_setall_s32(n+2);
for( ; k <= len - vecsize; k += vecsize )
{
v_float32 rbin = vx_load(RBin + k);
v_float32 cbin = vx_load(CBin + k);
v_float32 obin = (vx_load(Ori + k) - __ori) * __bins_per_rad;
v_float32 mag = vx_load(Mag + k) * vx_load(W + k);
v_float32 rbin = vx_load_aligned(RBin + k);
v_float32 cbin = vx_load_aligned(CBin + k);
v_float32 obin = (vx_load_aligned(Ori + k) - __ori) * __bins_per_rad;
v_float32 mag = vx_load_aligned(Mag + k) * vx_load_aligned(W + k);
v_int32 r0 = v_floor(rbin);
v_int32 c0 = v_floor(cbin);
@@ -723,7 +732,7 @@ void calcSIFTDescriptor(
hist[idx] += hist[idx+n];
hist[idx+1] += hist[idx+n+1];
for( k = 0; k < n; k++ )
dst[(i*d + j)*n + k] = hist[idx+k];
rawDst[(i*d + j)*n + k] = hist[idx+k];
}
// copy histogram to the descriptor,
// apply hysteresis thresholding
@@ -735,17 +744,17 @@ void calcSIFTDescriptor(
#if CV_SIMD
{
v_float32 __nrm2 = vx_setzero_f32();
v_float32 __dst;
v_float32 __rawDst;
for( ; k <= len - v_float32::nlanes; k += v_float32::nlanes )
{
__dst = vx_load(dst + k);
__nrm2 = v_fma(__dst, __dst, __nrm2);
__rawDst = vx_load_aligned(rawDst + k);
__nrm2 = v_fma(__rawDst, __rawDst, __nrm2);
}
nrm2 = (float)v_reduce_sum(__nrm2);
}
#endif
for( ; k < len; k++ )
nrm2 += dst[k]*dst[k];
nrm2 += rawDst[k]*rawDst[k];
float thr = std::sqrt(nrm2)*SIFT_DESCR_MAG_THR;
@@ -760,9 +769,9 @@ void calcSIFTDescriptor(
__m256 __thr = _mm256_set1_ps(thr);
for( ; i <= len - 8; i += 8 )
{
__dst = _mm256_loadu_ps(&dst[i]);
__dst = _mm256_loadu_ps(&rawDst[i]);
__dst = _mm256_min_ps(__dst, __thr);
_mm256_storeu_ps(&dst[i], __dst);
_mm256_storeu_ps(&rawDst[i], __dst);
#if CV_FMA3
__nrm2 = _mm256_fmadd_ps(__dst, __dst, __nrm2);
#else
@@ -776,44 +785,78 @@ void calcSIFTDescriptor(
#endif
for( ; i < len; i++ )
{
float val = std::min(dst[i], thr);
dst[i] = val;
float val = std::min(rawDst[i], thr);
rawDst[i] = val;
nrm2 += val*val;
}
nrm2 = SIFT_INT_DESCR_FCTR/std::max(std::sqrt(nrm2), FLT_EPSILON);
#if 1
k = 0;
if( dstMat.type() == CV_32F )
{
float* dst = dstMat.ptr<float>(row);
#if CV_SIMD
v_float32 __dst;
v_float32 __min = vx_setzero_f32();
v_float32 __max = vx_setall_f32(255.0f); // max of uchar
v_float32 __nrm2 = vx_setall_f32(nrm2);
for( k = 0; k <= len - v_float32::nlanes; k += v_float32::nlanes )
{
v_float32 __dst;
v_float32 __min = vx_setzero_f32();
v_float32 __max = vx_setall_f32(255.0f); // max of uchar
v_float32 __nrm2 = vx_setall_f32(nrm2);
for( k = 0; k <= len - v_float32::nlanes; k += v_float32::nlanes )
{
__dst = vx_load(dst + k);
__dst = v_min(v_max(v_cvt_f32(v_round(__dst * __nrm2)), __min), __max);
v_store(dst + k, __dst);
}
__dst = vx_load_aligned(rawDst + k);
__dst = v_min(v_max(v_cvt_f32(v_round(__dst * __nrm2)), __min), __max);
v_store(dst + k, __dst);
}
#endif
for( ; k < len; k++ )
{
dst[k] = saturate_cast<uchar>(dst[k]*nrm2);
dst[k] = saturate_cast<uchar>(rawDst[k]*nrm2);
}
}
else // CV_8U
{
uint8_t* dst = dstMat.ptr<uint8_t>(row);
#if CV_SIMD
v_float32 __dst0, __dst1;
v_uint16 __pack01;
v_float32 __nrm2 = vx_setall_f32(nrm2);
for( k = 0; k <= len - v_float32::nlanes * 2; k += v_float32::nlanes * 2 )
{
__dst0 = vx_load_aligned(rawDst + k);
__dst1 = vx_load_aligned(rawDst + k + v_float32::nlanes);
__pack01 = v_pack_u(v_round(__dst0 * __nrm2), v_round(__dst1 * __nrm2));
v_pack_store(dst + k, __pack01);
}
#endif
for( ; k < len; k++ )
{
dst[k] = saturate_cast<uchar>(rawDst[k]*nrm2);
}
}
#else
float* dst = dstMat.ptr<float>(row);
float nrm1 = 0;
for( k = 0; k < len; k++ )
{
dst[k] *= nrm2;
nrm1 += dst[k];
rawDst[k] *= nrm2;
nrm1 += rawDst[k];
}
nrm1 = 1.f/std::max(nrm1, FLT_EPSILON);
if( dstMat.type() == CV_32F )
{
for( k = 0; k < len; k++ )
{
dst[k] = std::sqrt(dst[k] * nrm1);//saturate_cast<uchar>(std::sqrt(dst[k] * nrm1)*SIFT_INT_DESCR_FCTR);
dst[k] = std::sqrt(rawDst[k] * nrm1);
}
}
else // CV_8U
{
for( k = 0; k < len; k++ )
{
dst[k] = saturate_cast<uchar>(std::sqrt(rawDst[k] * nrm1)*SIFT_INT_DESCR_FCTR);
}
}
#endif
}