opencv/modules/gpu/doc/object_detection.rst

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Object Detection
================
.. highlight:: cpp
.. index:: gpu::HOGDescriptor
.. _gpu::HOGDescriptor:
gpu::HOGDescriptor
------------------
`id=0.263285034412 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor>`__
.. ctype:: gpu::HOGDescriptor
Histogram of Oriented Gradients
dalal_hog
descriptor and detector.
::
struct CV_EXPORTS HOGDescriptor
{
enum { DEFAULT_WIN_SIGMA = -1 };
enum { DEFAULT_NLEVELS = 64 };
enum { DESCR_FORMAT_ROW_BY_ROW, DESCR_FORMAT_COL_BY_COL };
HOGDescriptor(Size win_size=Size(64, 128), Size block_size=Size(16, 16),
Size block_stride=Size(8, 8), Size cell_size=Size(8, 8),
int nbins=9, double win_sigma=DEFAULT_WIN_SIGMA,
double threshold_L2hys=0.2, bool gamma_correction=true,
int nlevels=DEFAULT_NLEVELS);
size_t getDescriptorSize() const;
size_t getBlockHistogramSize() const;
void setSVMDetector(const vector<float>& detector);
static vector<float> getDefaultPeopleDetector();
static vector<float> getPeopleDetector48x96();
static vector<float> getPeopleDetector64x128();
void detect(const GpuMat& img, vector<Point>& found_locations,
double hit_threshold=0, Size win_stride=Size(),
Size padding=Size());
void detectMultiScale(const GpuMat& img, vector<Rect>& found_locations,
double hit_threshold=0, Size win_stride=Size(),
Size padding=Size(), double scale0=1.05,
int group_threshold=2);
void getDescriptors(const GpuMat& img, Size win_stride,
GpuMat& descriptors,
int descr_format=DESCR_FORMAT_COL_BY_COL);
Size win_size;
Size block_size;
Size block_stride;
Size cell_size;
int nbins;
double win_sigma;
double threshold_L2hys;
bool gamma_correction;
int nlevels;
private:
// Hidden
}
..
Interfaces of all methods are kept similar to CPU HOG descriptor and detector analogues as much as possible.
.. index:: gpu::HOGDescriptor::HOGDescriptor
cv::gpu::HOGDescriptor::HOGDescriptor
-------------------------------------
`id=0.377426649644 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AHOGDescriptor>`__
.. cfunction:: HOGDescriptor::HOGDescriptor(Size win_size=Size(64, 128),
Size block_size=Size(16, 16), Size block_stride=Size(8, 8),
Size cell_size=Size(8, 8), int nbins=9,
double win_sigma=DEFAULT_WIN_SIGMA,
double threshold_L2hys=0.2, bool gamma_correction=true,
int nlevels=DEFAULT_NLEVELS)
Creates HOG descriptor and detector.
:param win_size: Detection window size. Must be aligned to block size and block stride.
:param block_size: Block size in pixels. Must be aligned to cell size. Only (16,16) is supported for now.
:param block_stride: Block stride. Must be a multiple of cell size.
:param cell_size: Cell size. Only (8, 8) is supported for now.
:param nbins: Number of bins. Only 9 bins per cell is supported for now.
:param win_sigma: Gaussian smoothing window parameter.
:param threshold_L2Hys: L2-Hys normalization method shrinkage.
:param gamma_correction: Do gamma correction preprocessing or not.
:param nlevels: Maximum number of detection window increases.
.. index:: gpu::HOGDescriptor::getDescriptorSize
cv::gpu::HOGDescriptor::getDescriptorSize
-----------------------------------------
`id=0.25703536307 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AgetDescriptorSize>`__
.. cfunction:: size_t HOGDescriptor::getDescriptorSize() const
Returns number of coefficients required for the classification.
.. index:: gpu::HOGDescriptor::getBlockHistogramSize
cv::gpu::HOGDescriptor::getBlockHistogramSize
---------------------------------------------
`id=0.91431196569 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AgetBlockHistogramSize>`__
.. cfunction:: size_t HOGDescriptor::getBlockHistogramSize() const
Returns block histogram size.
.. index:: gpu::HOGDescriptor::setSVMDetector
cv::gpu::HOGDescriptor::setSVMDetector
--------------------------------------
`id=0.719708439759 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AsetSVMDetector>`__
.. cfunction:: void HOGDescriptor::setSVMDetector(const vector<float>\& detector)
Sets coefficients for the linear SVM classifier.
.. index:: gpu::HOGDescriptor::getDefaultPeopleDetector
cv::gpu::HOGDescriptor::getDefaultPeopleDetector
------------------------------------------------
`id=0.941470897866 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AgetDefaultPeopleDetector>`__
.. cfunction:: static vector<float> HOGDescriptor::getDefaultPeopleDetector()
Returns coefficients of the classifier trained for people detection (for default window size).
.. index:: gpu::HOGDescriptor::getPeopleDetector48x96
cv::gpu::HOGDescriptor::getPeopleDetector48x96
----------------------------------------------
`id=0.600273723778 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AgetPeopleDetector48x96>`__
.. cfunction:: static vector<float> HOGDescriptor::getPeopleDetector48x96()
Returns coefficients of the classifier trained for people detection (for 48x96 windows).
.. index:: gpu::HOGDescriptor::getPeopleDetector64x128
cv::gpu::HOGDescriptor::getPeopleDetector64x128
-----------------------------------------------
`id=0.583356812364 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AgetPeopleDetector64x128>`__
.. cfunction:: static vector<float> HOGDescriptor::getPeopleDetector64x128()
Returns coefficients of the classifier trained for people detection (for 64x128 windows).
.. index:: gpu::HOGDescriptor::detect
cv::gpu::HOGDescriptor::detect
------------------------------
`id=0.0364241115122 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3Adetect>`__
.. cfunction:: void HOGDescriptor::detect(const GpuMat\& img,
vector<Point>\& found_locations, double hit_threshold=0,
Size win_stride=Size(), Size padding=Size())
Perfroms object detection without multiscale window.
:param img: Source image. ``CV_8UC1`` and ``CV_8UC4`` types are supported for now.
:param found_locations: Will contain left-top corner points of detected objects boundaries.
:param hit_threshold: Threshold for the distance between features and SVM classifying plane. Usually it's 0 and should be specfied in the detector coefficients (as the last free coefficient), but if the free coefficient is omitted (it's allowed) you can specify it manually here.
:param win_stride: Window stride. Must be a multiple of block stride.
:param padding: Mock parameter to keep CPU interface compatibility. Must be (0,0).
.. index:: gpu::HOGDescriptor::detectMultiScale
cv::gpu::HOGDescriptor::detectMultiScale
----------------------------------------
`id=0.125190830083 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AdetectMultiScale>`__
.. cfunction:: void HOGDescriptor::detectMultiScale(const GpuMat\& img,
vector<Rect>\& found_locations, double hit_threshold=0,
Size win_stride=Size(), Size padding=Size(),
double scale0=1.05, int group_threshold=2)
Perfroms object detection with multiscale window.
:param img: Source image. See :func:`gpu::HOGDescriptor::detect` for type limitations.
:param found_locations: Will contain detected objects boundaries.
:param hit_threshold: The threshold for the distance between features and SVM classifying plane. See :func:`gpu::HOGDescriptor::detect` for details.
:param win_stride: Window stride. Must be a multiple of block stride.
:param padding: Mock parameter to keep CPU interface compatibility. Must be (0,0).
:param scale0: Coefficient of the detection window increase.
:param group_threshold: After detection some objects could be covered by many rectangles. This coefficient regulates similarity threshold. 0 means don't perform grouping.
See :func:`groupRectangles` .
.. index:: gpu::HOGDescriptor::getDescriptors
cv::gpu::HOGDescriptor::getDescriptors
--------------------------------------
`id=0.128234884479 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3AHOGDescriptor%3A%3AgetDescriptors>`__
.. cfunction:: void HOGDescriptor::getDescriptors(const GpuMat\& img,
Size win_stride, GpuMat\& descriptors,
int descr_format=DESCR_FORMAT_COL_BY_COL)
Returns block descriptors computed for the whole image. It's mainly used for classifier learning purposes.
:param img: Source image. See :func:`gpu::HOGDescriptor::detect` for type limitations.
:param win_stride: Window stride. Must be a multiple of block stride.
:param descriptors: 2D array of descriptors.
:param descr_format: Descriptor storage format:
* **DESCR_FORMAT_ROW_BY_ROW** Row-major order.
* **DESCR_FORMAT_COL_BY_COL** Column-major order.
.. index:: gpu::CascadeClassifier_GPU
.. _gpu::CascadeClassifier_GPU:
gpu::CascadeClassifier_GPU
--------------------------
`id=0.362290729184 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/gpu%3A%3ACascadeClassifier_GPU>`__
.. ctype:: gpu::CascadeClassifier_GPU
The cascade classifier class for object detection.
::
class CV_EXPORTS CascadeClassifier_GPU
{
public:
CascadeClassifier_GPU();
CascadeClassifier_GPU(const string& filename);
~CascadeClassifier_GPU();
bool empty() const;
bool load(const string& filename);
void release();
/* returns number of detected objects */
int detectMultiScale( const GpuMat& image, GpuMat& objectsBuf, double scaleFactor=1.2, int minNeighbors=4, Size minSize=Size());
/* Finds only the largest object. Special mode for need to training*/
bool findLargestObject;
/* Draws rectangles in input image */
bool visualizeInPlace;
Size getClassifierSize() const;
};
..
.. index:: cv::gpu::CascadeClassifier_GPU::CascadeClassifier_GPU
.. _cv::gpu::CascadeClassifier_GPU::CascadeClassifier_GPU:
cv::gpu::CascadeClassifier_GPU::CascadeClassifier_GPU
-----------------------------------------------------
`id=0.502164537388 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/cv%3A%3Agpu%3A%3ACascadeClassifier_GPU%3A%3ACascadeClassifier_GPU>`__
.. cfunction:: cv::CascadeClassifier_GPU(const string\& filename)
Loads the classifier from file.
:param filename: Name of file from which classifier will be load. Only old haar classifier (trained by haartraining application) and NVidia's nvbin are supported.
.. index:: cv::gpu::CascadeClassifier_GPU::empty
.. _cv::gpu::CascadeClassifier_GPU::empty:
cv::gpu::CascadeClassifier_GPU::empty
-------------------------------------
`id=0.00879679914574 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/cv%3A%3Agpu%3A%3ACascadeClassifier_GPU%3A%3Aempty>`__
.. cfunction:: bool CascadeClassifier_GPU::empty() const
Checks if the classifier has been loaded or not.
.. index:: cv::gpu::CascadeClassifier_GPU::load
.. _cv::gpu::CascadeClassifier_GPU::load:
cv::gpu::CascadeClassifier_GPU::load
------------------------------------
`id=0.831994730738 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/cv%3A%3Agpu%3A%3ACascadeClassifier_GPU%3A%3Aload>`__
.. cfunction:: bool CascadeClassifier_GPU::load(const string\& filename)
Loads the classifier from file. The previous content is destroyed.
:param filename: Name of file from which classifier will be load. Only old haar classifier (trained by haartraining application) and NVidia's nvbin are supported.
.. index:: cv::gpu::CascadeClassifier_GPU::release
.. _cv::gpu::CascadeClassifier_GPU::release:
cv::gpu::CascadeClassifier_GPU::release
---------------------------------------
`id=0.524456582811 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/cv%3A%3Agpu%3A%3ACascadeClassifier_GPU%3A%3Arelease>`__
.. cfunction:: void CascadeClassifier_GPU::release()
Destroys loaded classifier.
.. index:: cv::gpu::CascadeClassifier_GPU::detectMultiScale
.. _cv::gpu::CascadeClassifier_GPU::detectMultiScale:
cv::gpu::CascadeClassifier_GPU::detectMultiScale
------------------------------------------------
`id=0.0605957110589 Comments from the Wiki <http://opencv.willowgarage.com/wiki/documentation/cpp/gpu/cv%3A%3Agpu%3A%3ACascadeClassifier_GPU%3A%3AdetectMultiScale>`__
.. cfunction:: int CascadeClassifier_GPU::detectMultiScale(const GpuMat\& image, GpuMat\& objectsBuf, double scaleFactor=1.2, int minNeighbors=4, Size minSize=Size())
Detects objects of different sizes in the input image. The detected objects are returned as a list of rectangles.
:param image: Matrix of type ``CV_8U`` containing the image in which to detect objects.
:param objects: Buffer to store detected objects (rectangles). If it is empty, it will be allocated with default size. If not empty, function will search not more than N objects, where N = sizeof(objectsBufer's data)/sizeof(cv::Rect).
:param scaleFactor: Specifies how much the image size is reduced at each image scale.
:param minNeighbors: Specifies how many neighbors should each candidate rectangle have to retain it.
:param minSize: The minimum possible object size. Objects smaller than that are ignored.
The function returns number of detected objects, so you can retrieve them as in following example:
::
cv::gpu::CascadeClassifier_GPU cascade_gpu(...);
Mat image_cpu = imread(...)
GpuMat image_gpu(image_cpu);
GpuMat objbuf;
int detections_number = cascade_gpu.detectMultiScale( image_gpu,
objbuf, 1.2, minNeighbors);
Mat obj_host;
// download only detected number of rectangles
objbuf.colRange(0, detections_number).download(obj_host);
Rect* faces = obj_host.ptr<Rect>();
for(int i = 0; i < detections_num; ++i)
cv::rectangle(image_cpu, faces[i], Scalar(255));
imshow("Faces", image_cpu);
..
See also:
:func:`CascadeClassifier::detectMultiScale`
.