Chiebot-Mirror
/
opencv_contrib
8
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Enabled FAST feature detection on specific image locations

Browse Source 
Some applications only want to know if there are feature at specific
locations. To fit these needs the FAST approach is extended in
FASTForPointSet to recieve a vector of locations and calculates the FAST
response on these positions. 
If it is below the threshold, it will be removed from the list.
pull/450/head
baudenri 10 years ago
parent 5e008c8758
commit 1c580151f4
2 changed files with 539 additions and 0 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Unified View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 26
      modules/xfeatures2d/include/opencv2/xfeatures2d.hpp
  2. 513
      modules/xfeatures2d/src/fast.cpp

26
modules/xfeatures2d/include/opencv2/xfeatures2d.hpp
Unescape View File

@ -259,6 +259,32 @@ public:
}; };
/** @brief Estimates cornerness for prespecified KeyPoints using the FAST algorithm
@param image grayscale image where keypoints (corners) are detected.
@param keypoints keypoints which should be tested to fit the FAST criteria. Keypoints not beeing
detected as corners are removed.
@param threshold threshold on difference between intensity of the central pixel and pixels of a
circle around this pixel.
@param nonmaxSuppression if true, non-maximum suppression is applied to detected corners
(keypoints).
@param type one of the three neighborhoods as defined in the paper:
FastFeatureDetector::TYPE_9_16, FastFeatureDetector::TYPE_7_12,
FastFeatureDetector::TYPE_5_8
Detects corners using the FAST algorithm by @cite Rosten06 .
*/
CV_EXPORTS void FASTForPointSet( InputArray image, CV_IN_OUT std::vector<KeyPoint>& keypoints,
int threshold, bool nonmaxSuppression=true, int type=FastFeatureDetector::TYPE_9_16);
void makeOffsets(int pixel[25], int row_stride, int patternSize);
template<int patternSize>
int cornerScore(const uchar* ptr, const int pixel[], int threshold);
//! @} //! @}
} }

513
modules/xfeatures2d/src/fast.cpp
Unescape View File

@ -0,0 +1,513 @@
/*M///////////////////////////////////////////////////////////////////////////////////////
//
// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
//
// By downloading, copying, installing or using the software you agree to this license.
// If you do not agree to this license, do not download, install,
// copy or use the software.
//
//
// License Agreement
// For Open Source Computer Vision Library
//
// Copyright (C) 2000-2008, Intel Corporation, all rights reserved.
// Copyright (C) 2009, Willow Garage Inc., all rights reserved.
// Third party copyrights are property of their respective owners.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// * Redistribution's of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistribution's in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * The name of the copyright holders may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// This software is provided by the copyright holders and contributors "as is" and
// any express or implied warranties, including, but not limited to, the implied
// warranties of merchantability and fitness for a particular purpose are disclaimed.
// In no event shall the Intel Corporation or contributors be liable for any direct,
// indirect, incidental, special, exemplary, or consequential damages
// (including, but not limited to, procurement of substitute goods or services;
// loss of use, data, or profits; or business interruption) however caused
// and on any theory of liability, whether in contract, strict liability,
// or tort (including negligence or otherwise) arising in any way out of
// the use of this software, even if advised of the possibility of such damage.
//
//M*/
#include <opencv2/xfeatures2d.hpp>
#ifndef VERIFY_CORNERS
#define VERIFY_CORNERS 0
#endif
namespace cv {
namespace xfeatures2d {
#if VERIFY_CORNERS
static void testCorner(const uchar* ptr, const int pixel[], int K, int N, int threshold) {
// check that with the computed "threshold" the pixel is still a corner
// and that with the increased-by-1 "threshold" the pixel is not a corner anymore
for( int delta = 0; delta <= 1; delta++ )
{
int v0 = std::min(ptr[0] + threshold + delta, 255);
int v1 = std::max(ptr[0] - threshold - delta, 0);
int c0 = 0, c1 = 0;
for( int k = 0; k < N; k++ )
{
int x = ptr[pixel[k]];
if(x > v0)
{
if( ++c0 > K )
break;
c1 = 0;
}
else if( x < v1 )
{
if( ++c1 > K )
break;
c0 = 0;
}
else
{
c0 = c1 = 0;
}
}
CV_Assert( (delta == 0 && std::max(c0, c1) > K) ||
(delta == 1 && std::max(c0, c1) <= K) );
}
}
#endif
template<>
int cornerScore<16>(const uchar* ptr, const int pixel[], int threshold)
{
const int K = 8, N = K*3 + 1;
int k, v = ptr[0];
short d[N];
for( k = 0; k < N; k++ )
d[k] = (short)(v - ptr[pixel[k]]);
#if CV_SSE2
__m128i q0 = _mm_set1_epi16(-1000), q1 = _mm_set1_epi16(1000);
for( k = 0; k < 16; k += 8 )
{
__m128i v0 = _mm_loadu_si128((__m128i*)(d+k+1));
__m128i v1 = _mm_loadu_si128((__m128i*)(d+k+2));
__m128i a = _mm_min_epi16(v0, v1);
__m128i b = _mm_max_epi16(v0, v1);
v0 = _mm_loadu_si128((__m128i*)(d+k+3));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+4));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+5));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+6));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+7));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+8));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k));
q0 = _mm_max_epi16(q0, _mm_min_epi16(a, v0));
q1 = _mm_min_epi16(q1, _mm_max_epi16(b, v0));
v0 = _mm_loadu_si128((__m128i*)(d+k+9));
q0 = _mm_max_epi16(q0, _mm_min_epi16(a, v0));
q1 = _mm_min_epi16(q1, _mm_max_epi16(b, v0));
}
q0 = _mm_max_epi16(q0, _mm_sub_epi16(_mm_setzero_si128(), q1));
q0 = _mm_max_epi16(q0, _mm_unpackhi_epi64(q0, q0));
q0 = _mm_max_epi16(q0, _mm_srli_si128(q0, 4));
q0 = _mm_max_epi16(q0, _mm_srli_si128(q0, 2));
threshold = (short)_mm_cvtsi128_si32(q0) - 1;
#else
int a0 = threshold;
for( k = 0; k < 16; k += 2 )
{
int a = std::min((int)d[k+1], (int)d[k+2]);
a = std::min(a, (int)d[k+3]);
if( a <= a0 )
continue;
a = std::min(a, (int)d[k+4]);
a = std::min(a, (int)d[k+5]);
a = std::min(a, (int)d[k+6]);
a = std::min(a, (int)d[k+7]);
a = std::min(a, (int)d[k+8]);
a0 = std::max(a0, std::min(a, (int)d[k]));
a0 = std::max(a0, std::min(a, (int)d[k+9]));
}
int b0 = -a0;
for( k = 0; k < 16; k += 2 )
{
int b = std::max((int)d[k+1], (int)d[k+2]);
b = std::max(b, (int)d[k+3]);
b = std::max(b, (int)d[k+4]);
b = std::max(b, (int)d[k+5]);
if( b >= b0 )
continue;
b = std::max(b, (int)d[k+6]);
b = std::max(b, (int)d[k+7]);
b = std::max(b, (int)d[k+8]);
b0 = std::min(b0, std::max(b, (int)d[k]));
b0 = std::min(b0, std::max(b, (int)d[k+9]));
}
threshold = -b0-1;
#endif
#if VERIFY_CORNERS
testCorner(ptr, pixel, K, N, threshold);
#endif
return threshold;
}
template<>
int cornerScore<12>(const uchar* ptr, const int pixel[], int threshold)
{
const int K = 6, N = K*3 + 1;
int k, v = ptr[0];
short d[N + 4];
for( k = 0; k < N; k++ )
d[k] = (short)(v - ptr[pixel[k]]);
#if CV_SSE2
for( k = 0; k < 4; k++ )
d[N+k] = d[k];
#endif
#if CV_SSE2
__m128i q0 = _mm_set1_epi16(-1000), q1 = _mm_set1_epi16(1000);
for( k = 0; k < 16; k += 8 )
{
__m128i v0 = _mm_loadu_si128((__m128i*)(d+k+1));
__m128i v1 = _mm_loadu_si128((__m128i*)(d+k+2));
__m128i a = _mm_min_epi16(v0, v1);
__m128i b = _mm_max_epi16(v0, v1);
v0 = _mm_loadu_si128((__m128i*)(d+k+3));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+4));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+5));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k+6));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+k));
q0 = _mm_max_epi16(q0, _mm_min_epi16(a, v0));
q1 = _mm_min_epi16(q1, _mm_max_epi16(b, v0));
v0 = _mm_loadu_si128((__m128i*)(d+k+7));
q0 = _mm_max_epi16(q0, _mm_min_epi16(a, v0));
q1 = _mm_min_epi16(q1, _mm_max_epi16(b, v0));
}
q0 = _mm_max_epi16(q0, _mm_sub_epi16(_mm_setzero_si128(), q1));
q0 = _mm_max_epi16(q0, _mm_unpackhi_epi64(q0, q0));
q0 = _mm_max_epi16(q0, _mm_srli_si128(q0, 4));
q0 = _mm_max_epi16(q0, _mm_srli_si128(q0, 2));
threshold = (short)_mm_cvtsi128_si32(q0) - 1;
#else
int a0 = threshold;
for( k = 0; k < 12; k += 2 )
{
int a = std::min((int)d[k+1], (int)d[k+2]);
if( a <= a0 )
continue;
a = std::min(a, (int)d[k+3]);
a = std::min(a, (int)d[k+4]);
a = std::min(a, (int)d[k+5]);
a = std::min(a, (int)d[k+6]);
a0 = std::max(a0, std::min(a, (int)d[k]));
a0 = std::max(a0, std::min(a, (int)d[k+7]));
}
int b0 = -a0;
for( k = 0; k < 12; k += 2 )
{
int b = std::max((int)d[k+1], (int)d[k+2]);
b = std::max(b, (int)d[k+3]);
b = std::max(b, (int)d[k+4]);
if( b >= b0 )
continue;
b = std::max(b, (int)d[k+5]);
b = std::max(b, (int)d[k+6]);
b0 = std::min(b0, std::max(b, (int)d[k]));
b0 = std::min(b0, std::max(b, (int)d[k+7]));
}
threshold = -b0-1;
#endif
#if VERIFY_CORNERS
testCorner(ptr, pixel, K, N, threshold);
#endif
return threshold;
}
template<>
int cornerScore<8>(const uchar* ptr, const int pixel[], int threshold)
{
const int K = 4, N = K*3 + 1;
int k, v = ptr[0];
short d[N];
for( k = 0; k < N; k++ )
d[k] = (short)(v - ptr[pixel[k]]);
#if CV_SSE2
__m128i v0 = _mm_loadu_si128((__m128i*)(d+1));
__m128i v1 = _mm_loadu_si128((__m128i*)(d+2));
__m128i a = _mm_min_epi16(v0, v1);
__m128i b = _mm_max_epi16(v0, v1);
v0 = _mm_loadu_si128((__m128i*)(d+3));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+4));
a = _mm_min_epi16(a, v0);
b = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d));
__m128i q0 = _mm_min_epi16(a, v0);
__m128i q1 = _mm_max_epi16(b, v0);
v0 = _mm_loadu_si128((__m128i*)(d+5));
q0 = _mm_max_epi16(q0, _mm_min_epi16(a, v0));
q1 = _mm_min_epi16(q1, _mm_max_epi16(b, v0));
q0 = _mm_max_epi16(q0, _mm_sub_epi16(_mm_setzero_si128(), q1));
q0 = _mm_max_epi16(q0, _mm_unpackhi_epi64(q0, q0));
q0 = _mm_max_epi16(q0, _mm_srli_si128(q0, 4));
q0 = _mm_max_epi16(q0, _mm_srli_si128(q0, 2));
threshold = (short)_mm_cvtsi128_si32(q0) - 1;
#else
int a0 = threshold;
for( k = 0; k < 8; k += 2 )
{
int a = std::min((int)d[k+1], (int)d[k+2]);
if( a <= a0 )
continue;
a = std::min(a, (int)d[k+3]);
a = std::min(a, (int)d[k+4]);
a0 = std::max(a0, std::min(a, (int)d[k]));
a0 = std::max(a0, std::min(a, (int)d[k+5]));
}
int b0 = -a0;
for( k = 0; k < 8; k += 2 )
{
int b = std::max((int)d[k+1], (int)d[k+2]);
b = std::max(b, (int)d[k+3]);
if( b >= b0 )
continue;
b = std::max(b, (int)d[k+4]);
b0 = std::min(b0, std::max(b, (int)d[k]));
b0 = std::min(b0, std::max(b, (int)d[k+5]));
}
threshold = -b0-1;
#endif
#if VERIFY_CORNERS
testCorner(ptr, pixel, K, N, threshold);
#endif
return threshold;
}
void makeOffsets(int pixel[25], int rowStride, int patternSize)
{
static const int offsets16[][2] =
{
{0, 3}, { 1, 3}, { 2, 2}, { 3, 1}, { 3, 0}, { 3, -1}, { 2, -2}, { 1, -3},
{0, -3}, {-1, -3}, {-2, -2}, {-3, -1}, {-3, 0}, {-3, 1}, {-2, 2}, {-1, 3}
};
static const int offsets12[][2] =
{
{0, 2}, { 1, 2}, { 2, 1}, { 2, 0}, { 2, -1}, { 1, -2},
{0, -2}, {-1, -2}, {-2, -1}, {-2, 0}, {-2, 1}, {-1, 2}
};
static const int offsets8[][2] =
{
{0, 1}, { 1, 1}, { 1, 0}, { 1, -1},
{0, -1}, {-1, -1}, {-1, 0}, {-1, 1}
};
const int (*offsets)[2] = patternSize == 16 ? offsets16 :
patternSize == 12 ? offsets12 :
patternSize == 8 ? offsets8 : 0;
CV_Assert(pixel && offsets);
int k = 0;
for( ; k < patternSize; k++ )
pixel[k] = offsets[k][0] + offsets[k][1] * rowStride;
for( ; k < 25; k++ )
pixel[k] = pixel[k - patternSize];
}
template<int patternSize>
void FASTForPointSet_t( InputArray image, std::vector<KeyPoint>& keypoints, int threshold, bool nonmaxSuppression ) {
Mat img = image.getMat();
const int K = patternSize/2, N = patternSize + K + 1;
int i, k, pixel[25];
makeOffsets(pixel, (int)img.step, patternSize);
keypoints.clear();
threshold = std::min(std::max(threshold, 0), 255);
uchar threshold_tab[512];
for( i = -255; i <= 255; i++ )
threshold_tab[i+255] = (uchar)(i < -threshold ? 1 : i > threshold ? 2 : 0);
AutoBuffer<uchar> _buf((img.cols+16)*3*(sizeof(int) + sizeof(uchar)) + 128);
uchar* buf[3];
buf[0] = _buf; buf[1] = buf[0] + img.cols; buf[2] = buf[1] + img.cols;
int* cpbuf[3];
cpbuf[0] = (int*)alignPtr(buf[2] + img.cols, sizeof(int)) + 1;
cpbuf[1] = cpbuf[0] + img.cols + 1;
cpbuf[2] = cpbuf[1] + img.cols + 1;
memset(buf[0], 0, img.cols*3);
// Calculate threshold for the keypoints
for (size_t keyPointIdx=0; keyPointIdx < keypoints.size(); keyPointIdx++) {
// Set response to -1:
// All keypoints with response <= 0 will be removed afterwards
keypoints[keyPointIdx].response = -1;
// Poiter to keyPoint in image
Point keyPoint = keypoints[keyPointIdx].pt;
const uchar* ptr = img.ptr<uchar>(keyPoint.y, keyPoint.x);
// value of the pixel at certain position
int v = ptr[0];
// Initialize Lookup table
// If k=v --> tab[k] is at the center of the thrshold table
// The threshold table is made as follows:
// -255 -threshold 0 +threshold 255
// 111111111111111111|0000000000000|0000000000000|222222222222222
const uchar* tab = &threshold_tab[0] - v + 255;
// Calculate the fast value
int d = tab[ptr[pixel[0]]] | tab[ptr[pixel[8]]];
if( d == 0 )
continue;
d &= tab[ptr[pixel[2]]] | tab[ptr[pixel[10]]];
d &= tab[ptr[pixel[4]]] | tab[ptr[pixel[12]]];
d &= tab[ptr[pixel[6]]] | tab[ptr[pixel[14]]];
if( d == 0 )
continue;
d &= tab[ptr[pixel[1]]] | tab[ptr[pixel[9]]];
d &= tab[ptr[pixel[3]]] | tab[ptr[pixel[11]]];
d &= tab[ptr[pixel[5]]] | tab[ptr[pixel[13]]];
d &= tab[ptr[pixel[7]]] | tab[ptr[pixel[15]]];
// For at least half pixels darker than v count the number
if( d & 1 )
{
int vt = v - threshold, count = 0;
for(k = 0; k < N; k++ )
{
int x = ptr[pixel[k]];
if(x < vt)
{
if( ++count > K )
{
// Calculate score
keypoints[keyPointIdx].response = (uchar)cornerScore<patternSize>(ptr, pixel, threshold);
// Non Maxima Supression I
if (nonmaxSuppression && keyPointIdx>0 && keypoints[keyPointIdx-1].response < keypoints[keyPointIdx].response) {
keypoints[keyPointIdx-1].response = -1;
}
break;
}
}
else
count = 0;
}
}
// For at least half pixels brighter than v count the number
if(d & 2 )
{
int vt = v + threshold, count = 0;
for(k = 0; k < N; k++ )
{
int x = ptr[pixel[k]];
if(x > vt)
{
if( ++count > K )
{
// Calculate score
keypoints[keyPointIdx].response = (uchar)cornerScore<patternSize>(ptr, pixel, threshold);
// Non Maxima Suppression I
if (nonmaxSuppression && keyPointIdx>0 &&keypoints[keyPointIdx-1].response < keypoints[keyPointIdx].response) {
keypoints[keyPointIdx-1].response = -1;
}
break;
}
}
else
count = 0;
}
}
}
// Remove unused Keypoints
size_t maxKeypointSize = keypoints.size();
for (size_t keyPointIdx=maxKeypointSize; keyPointIdx > 0;) {
keyPointIdx--;
if (keypoints[keyPointIdx].response <= 0) {
keypoints.erase(keypoints.begin() + keyPointIdx);
} else if (nonmaxSuppression && keyPointIdx>0 && keypoints[keyPointIdx-1].response > keypoints[keyPointIdx].response) {
// Non Maxima Suppression II
keypoints.erase(keypoints.begin() + keyPointIdx);
}
}
}
void FASTForPointSet(InputArray _img, std::vector<KeyPoint>& keypoints, int threshold, bool nonmax_suppression, int type)
{
if (keypoints.empty()) {
FAST(_img, keypoints, threshold, nonmax_suppression, type);
return;
}
switch(type) {
case FastFeatureDetector::TYPE_5_8:
FASTForPointSet_t<8>(_img, keypoints, threshold, nonmax_suppression);
break;
case FastFeatureDetector::TYPE_7_12:
FASTForPointSet_t<12>(_img, keypoints, threshold, nonmax_suppression);
break;
case FastFeatureDetector::TYPE_9_16:
FASTForPointSet_t<16>(_img, keypoints, threshold, nonmax_suppression);
break;
}
}
}
}
Write Preview
Loading…
Cancel
Save