gstreamer/ext/opencv/gstsegmentation.cpp

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/*
* GStreamer
* Copyright (C) 2013 Miguel Casas-Sanchez <miguelecasassanchez@gmail.com>
* Except: Parts of code inside the preprocessor define CODE_FROM_OREILLY_BOOK,
* which are downloaded from O'Reilly website
* [http://examples.oreilly.com/9780596516130/]
* and adapted. Its license reads:
* "Oct. 3, 2008
* Right to use this code in any way you want without warrenty, support or
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* any guarantee of it working. "
*
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
* Alternatively, the contents of this file may be used under the
* GNU Lesser General Public License Version 2.1 (the "LGPL"), in
* which case the following provisions apply instead of the ones
* mentioned above:
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#define CODE_FROM_OREILLY_BOOK
/**
* SECTION:element-segmentation
*
* This element creates and updates a fg/bg model using one of several approaches.
* The one called "codebook" refers to the codebook approach following the opencv
* O'Reilly book [1] implementation of the algorithm described in K. Kim,
* T. H. Chalidabhongse, D. Harwood and L. Davis [2]. BackgroundSubtractorMOG [3],
* or MOG for shorts, refers to a Gaussian Mixture-based Background/Foreground
* Segmentation Algorithm. OpenCV MOG implements the algorithm described in [4].
* BackgroundSubtractorMOG2 [5], refers to another Gaussian Mixture-based
* Background/Foreground segmentation algorithm. OpenCV MOG2 implements the
* algorithm described in [6] and [7].
*
* [1] Learning OpenCV: Computer Vision with the OpenCV Library by Gary Bradski
* and Adrian Kaehler, Published by O'Reilly Media, October 3, 2008
* [2] "Real-time Foreground-Background Segmentation using Codebook Model",
* Real-time Imaging, Volume 11, Issue 3, Pages 167-256, June 2005.
* [3] http://opencv.itseez.com/modules/video/doc/motion_analysis_and_object_tracking.html#backgroundsubtractormog
* [4] P. KadewTraKuPong and R. Bowden, "An improved adaptive background
* mixture model for real-time tracking with shadow detection", Proc. 2nd
* European Workshop on Advanced Video-Based Surveillance Systems, 2001
* [5] http://opencv.itseez.com/modules/video/doc/motion_analysis_and_object_tracking.html#backgroundsubtractormog2
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* [6] Z.Zivkovic, "Improved adaptive Gaussian mixture model for background
* subtraction", International Conference Pattern Recognition, UK, August, 2004.
* [7] Z.Zivkovic, F. van der Heijden, "Efficient Adaptive Density Estimation
* per Image Pixel for the Task of Background Subtraction", Pattern Recognition
* Letters, vol. 27, no. 7, pages 773-780, 2006.
*
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* ## Example launch line
*
* |[
* gst-launch-1.0 v4l2src device=/dev/video0 ! videoconvert ! segmentation test-mode=true method=2 ! videoconvert ! ximagesink
* ]|
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "gstsegmentation.h"
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#include <opencv2/imgproc.hpp>
GST_DEBUG_CATEGORY_STATIC (gst_segmentation_debug);
#define GST_CAT_DEFAULT gst_segmentation_debug
using namespace cv;
/* Filter signals and args */
enum
{
/* FILL ME */
LAST_SIGNAL
};
enum
{
PROP_0,
PROP_TEST_MODE,
PROP_METHOD,
PROP_LEARNING_RATE
};
typedef enum
{
METHOD_BOOK,
METHOD_MOG,
METHOD_MOG2
} GstSegmentationMethod;
#define DEFAULT_TEST_MODE FALSE
#define DEFAULT_METHOD METHOD_MOG2
#define DEFAULT_LEARNING_RATE 0.01
#define GST_TYPE_SEGMENTATION_METHOD (gst_segmentation_method_get_type ())
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static GType
gst_segmentation_method_get_type (void)
{
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static GType etype = 0;
if (etype == 0) {
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static const GEnumValue values[] = {
{METHOD_BOOK, "Codebook-based segmentation (Bradski2008)", "codebook"},
{METHOD_MOG, "Mixture-of-Gaussians segmentation (Bowden2001)", "mog"},
{METHOD_MOG2, "Mixture-of-Gaussians segmentation (Zivkovic2004)", "mog2"},
{0, NULL, NULL},
};
etype = g_enum_register_static ("GstSegmentationMethod", values);
}
return etype;
}
G_DEFINE_TYPE_WITH_CODE (GstSegmentation, gst_segmentation,
GST_TYPE_OPENCV_VIDEO_FILTER,
GST_DEBUG_CATEGORY_INIT (gst_segmentation_debug, "segmentation", 0,
"Performs Foreground/Background segmentation in video sequences");
);
GST_ELEMENT_REGISTER_DEFINE (segmentation, "segmentation", GST_RANK_NONE,
GST_TYPE_SEGMENTATION);
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static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("RGBA")));
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static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("RGBA")));
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static void
gst_segmentation_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec);
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static void
gst_segmentation_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec);
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static GstFlowReturn gst_segmentation_transform_ip (GstOpencvVideoFilter *
filter, GstBuffer * buffer, Mat img);
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static void gst_segmentation_finalize (GObject * object);
static gboolean gst_segmentation_set_caps (GstOpencvVideoFilter * filter,
gint in_width, gint in_height, int in_cv_type, gint out_width,
gint out_height, int out_cv_type);
/* Codebook algorithm + connected components functions*/
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static int update_codebook (unsigned char *p, codeBook * c,
unsigned *cbBounds, int numChannels);
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static int clear_stale_entries (codeBook * c);
static unsigned char background_diff (unsigned char *p, codeBook * c,
int numChannels, int *minMod, int *maxMod);
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static void find_connected_components (Mat mask, int poly1_hull0,
float perimScale);
/* MOG (Mixture-of-Gaussians functions */
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static int run_mog_iteration (GstSegmentation * filter);
static int run_mog2_iteration (GstSegmentation * filter);
/* initialize the segmentation's class */
static void
gst_segmentation_class_init (GstSegmentationClass * klass)
{
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GObjectClass *gobject_class;
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
GstOpencvVideoFilterClass *cvfilter_class =
(GstOpencvVideoFilterClass *) klass;
gobject_class = (GObjectClass *) klass;
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gobject_class->finalize = gst_segmentation_finalize;
gobject_class->set_property = gst_segmentation_set_property;
gobject_class->get_property = gst_segmentation_get_property;
cvfilter_class->cv_trans_ip_func = gst_segmentation_transform_ip;
cvfilter_class->cv_set_caps = gst_segmentation_set_caps;
g_object_class_install_property (gobject_class, PROP_METHOD,
g_param_spec_enum ("method",
"Segmentation method to use",
"Segmentation method to use",
GST_TYPE_SEGMENTATION_METHOD, DEFAULT_METHOD,
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
g_object_class_install_property (gobject_class, PROP_TEST_MODE,
g_param_spec_boolean ("test-mode", "test-mode",
"If true, the output RGB is overwritten with the calculated foreground (white color)",
DEFAULT_TEST_MODE, (GParamFlags)
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
g_object_class_install_property (gobject_class, PROP_LEARNING_RATE,
g_param_spec_float ("learning-rate", "learning-rate",
"Speed with which a motionless foreground pixel would become background (inverse of number of frames)",
0, 1, DEFAULT_LEARNING_RATE, (GParamFlags) (G_PARAM_READWRITE)));
gst_element_class_set_static_metadata (element_class,
"Foreground/background video sequence segmentation",
"Filter/Effect/Video",
"Create a Foregound/Background mask applying a particular algorithm",
"Miguel Casas-Sanchez <miguelecasassanchez@gmail.com>");
gst_element_class_add_static_pad_template (element_class, &src_factory);
gst_element_class_add_static_pad_template (element_class, &sink_factory);
gst_type_mark_as_plugin_api (GST_TYPE_SEGMENTATION_METHOD, (GstPluginAPIFlags) 0);
}
/* initialize the new element
* instantiate pads and add them to element
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* set pad callback functions
* initialize instance structure
*/
static void
gst_segmentation_init (GstSegmentation * filter)
{
filter->method = DEFAULT_METHOD;
filter->test_mode = DEFAULT_TEST_MODE;
filter->framecount = 0;
filter->learning_rate = DEFAULT_LEARNING_RATE;
gst_opencv_video_filter_set_in_place (GST_OPENCV_VIDEO_FILTER (filter), TRUE);
}
static void
gst_segmentation_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
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GstSegmentation *filter = GST_SEGMENTATION (object);
switch (prop_id) {
case PROP_METHOD:
filter->method = g_value_get_enum (value);
break;
case PROP_TEST_MODE:
filter->test_mode = g_value_get_boolean (value);
break;
case PROP_LEARNING_RATE:
filter->learning_rate = g_value_get_float (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_segmentation_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
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GstSegmentation *filter = GST_SEGMENTATION (object);
switch (prop_id) {
case PROP_METHOD:
g_value_set_enum (value, filter->method);
break;
case PROP_TEST_MODE:
g_value_set_boolean (value, filter->test_mode);
break;
case PROP_LEARNING_RATE:
g_value_set_float (value, filter->learning_rate);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
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static gboolean
gst_segmentation_set_caps (GstOpencvVideoFilter * filter, gint in_width,
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gint in_height, int in_cv_type,
gint out_width, gint out_height, int out_cv_type)
{
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GstSegmentation *segmentation = GST_SEGMENTATION (filter);
Size size;
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size = Size (in_width, in_height);
segmentation->width = in_width;
segmentation->height = in_height;
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segmentation->cvRGB.create (size, CV_8UC3);
segmentation->cvYUV.create (size, CV_8UC3);
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segmentation->cvFG = Mat::zeros (size, CV_8UC1);
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segmentation->ch1.create (size, CV_8UC1);
segmentation->ch2.create (size, CV_8UC1);
segmentation->ch3.create (size, CV_8UC1);
/* Codebook method */
segmentation->TcodeBook = (codeBook *)
g_malloc (sizeof (codeBook) *
(segmentation->width * segmentation->height + 1));
for (int j = 0; j < segmentation->width * segmentation->height; j++) {
segmentation->TcodeBook[j].numEntries = 0;
segmentation->TcodeBook[j].t = 0;
}
segmentation->learning_interval = (int) (1.0 / segmentation->learning_rate);
/* Mixture-of-Gaussians (mog) methods */
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segmentation->mog = bgsegm::createBackgroundSubtractorMOG ();
segmentation->mog2 = createBackgroundSubtractorMOG2 ();
return TRUE;
}
/* Clean up */
static void
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gst_segmentation_finalize (GObject * object)
{
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GstSegmentation *filter = GST_SEGMENTATION (object);
filter->cvRGB.release ();
filter->cvYUV.release ();
filter->cvFG.release ();
filter->ch1.release ();
filter->ch2.release ();
filter->ch3.release ();
filter->mog.release ();
filter->mog2.release ();
g_free (filter->TcodeBook);
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G_OBJECT_CLASS (gst_segmentation_parent_class)->finalize (object);
}
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static GstFlowReturn
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gst_segmentation_transform_ip (GstOpencvVideoFilter * cvfilter,
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GstBuffer * buffer, Mat img)
{
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GstSegmentation *filter = GST_SEGMENTATION (cvfilter);
int j;
filter->framecount++;
/* Image preprocessing: color space conversion etc */
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cvtColor (img, filter->cvRGB, COLOR_RGBA2RGB);
cvtColor (filter->cvRGB, filter->cvYUV, COLOR_RGB2YCrCb);
/* Create and update a fg/bg model using a codebook approach following the
* opencv O'Reilly book [1] implementation of the algo described in [2].
*
* [1] Learning OpenCV: Computer Vision with the OpenCV Library by Gary
* Bradski and Adrian Kaehler, Published by O'Reilly Media, October 3, 2008
* [2] "Real-time Foreground-Background Segmentation using Codebook Model",
* Real-time Imaging, Volume 11, Issue 3, Pages 167-256, June 2005. */
if (METHOD_BOOK == filter->method) {
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unsigned cbBounds[3] = { 10, 5, 5 };
int minMod[3] = { 20, 20, 20 }, maxMod[3] = {
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20, 20, 20
};
if (filter->framecount < 30) {
/* Learning background phase: update_codebook on every frame */
for (j = 0; j < filter->width * filter->height; j++) {
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update_codebook (filter->cvYUV.data + j * 3,
(codeBook *) & (filter->TcodeBook[j]), cbBounds, 3);
}
} else {
/* this updating is responsible for FG becoming BG again */
if (filter->framecount % filter->learning_interval == 0) {
for (j = 0; j < filter->width * filter->height; j++) {
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update_codebook (filter->cvYUV.data + j * 3,
(codeBook *) & (filter->TcodeBook[j]), cbBounds, 3);
}
}
if (filter->framecount % 60 == 0) {
for (j = 0; j < filter->width * filter->height; j++)
clear_stale_entries ((codeBook *) & (filter->TcodeBook[j]));
}
for (j = 0; j < filter->width * filter->height; j++) {
if (background_diff
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(filter->cvYUV.data + j * 3,
(codeBook *) & (filter->TcodeBook[j]), 3, minMod, maxMod)) {
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filter->cvFG.data[j] = (char) 255;
} else {
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filter->cvFG.data[j] = 0;
}
}
}
/* 3rd param is the smallest area to show: (w+h)/param , in pixels */
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find_connected_components (filter->cvFG, 1, 10000);
}
/* Create the foreground and background masks using BackgroundSubtractorMOG [1],
* Gaussian Mixture-based Background/Foreground segmentation algorithm. OpenCV
* MOG implements the algorithm described in [2].
*
* [1] http://opencv.itseez.com/modules/video/doc/motion_analysis_and_object_tracking.html#backgroundsubtractormog
* [2] P. KadewTraKuPong and R. Bowden, "An improved adaptive background
* mixture model for real-time tracking with shadow detection", Proc. 2nd
* European Workshop on Advanced Video-Based Surveillance Systems, 2001
*/
else if (METHOD_MOG == filter->method) {
run_mog_iteration (filter);
}
/* Create the foreground and background masks using BackgroundSubtractorMOG2
* [1], Gaussian Mixture-based Background/Foreground segmentation algorithm.
* OpenCV MOG2 implements the algorithm described in [2] and [3].
*
* [1] http://opencv.itseez.com/modules/video/doc/motion_analysis_and_object_tracking.html#backgroundsubtractormog2
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* [2] Z.Zivkovic, "Improved adaptive Gaussian mixture model for background
* subtraction", International Conference Pattern Recognition, UK, Aug 2004.
* [3] Z.Zivkovic, F. van der Heijden, "Efficient Adaptive Density Estimation
* per Image Pixel for the Task of Background Subtraction", Pattern
* Recognition Letters, vol. 27, no. 7, pages 773-780, 2006. */
else if (METHOD_MOG2 == filter->method) {
run_mog2_iteration (filter);
}
/* if we want to test_mode, just overwrite the output */
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std::vector < cv::Mat > channels (3);
if (filter->test_mode) {
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cvtColor (filter->cvFG, filter->cvRGB, COLOR_GRAY2RGB);
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split (filter->cvRGB, channels);
} else
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split (img, channels);
channels.push_back (filter->cvFG);
/* copy anyhow the fg/bg to the alpha channel in the output image */
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merge (channels, img);
return GST_FLOW_OK;
}
#ifdef CODE_FROM_OREILLY_BOOK /* See license at the beginning of the page */
/*
int update_codebook(uchar *p, codeBook &c, unsigned cbBounds)
Updates the codebook entry with a new data point
p Pointer to a YUV or HSI pixel
c Codebook for this pixel
cbBounds Learning bounds for codebook (Rule of thumb: 10)
numChannels Number of color channels we¡¯re learning
NOTES:
cvBounds must be of length equal to numChannels
RETURN
codebook index
*/
int
update_codebook (unsigned char *p, codeBook * c, unsigned *cbBounds,
int numChannels)
{
/* c->t+=1; */
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unsigned int high[3], low[3];
int n, i;
int matchChannel;
for (n = 0; n < numChannels; n++) {
high[n] = p[n] + cbBounds[n];
if (high[n] > 255)
high[n] = 255;
if (p[n] > cbBounds[n])
low[n] = p[n] - cbBounds[n];
else
low[n] = 0;
}
/* SEE IF THIS FITS AN EXISTING CODEWORD */
for (i = 0; i < c->numEntries; i++) {
matchChannel = 0;
for (n = 0; n < numChannels; n++) {
if ((c->cb[i]->learnLow[n] <= *(p + n)) &&
/* Found an entry for this channel */
(*(p + n) <= c->cb[i]->learnHigh[n])) {
matchChannel++;
}
}
if (matchChannel == numChannels) { /* If an entry was found */
c->cb[i]->t_last_update = c->t;
/* adjust this codeword for the first channel */
for (n = 0; n < numChannels; n++) {
if (c->cb[i]->max[n] < *(p + n)) {
c->cb[i]->max[n] = *(p + n);
} else if (c->cb[i]->min[n] > *(p + n)) {
c->cb[i]->min[n] = *(p + n);
}
}
break;
}
}
/* OVERHEAD TO TRACK POTENTIAL STALE ENTRIES */
for (int s = 0; s < c->numEntries; s++) {
/* Track which codebook entries are going stale: */
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int negRun = c->t - c->cb[s]->t_last_update;
if (c->cb[s]->stale < negRun)
c->cb[s]->stale = negRun;
}
/* ENTER A NEW CODEWORD IF NEEDED */
if (i == c->numEntries) { /* if no existing codeword found, make one */
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code_element **foo =
(code_element **) g_malloc (sizeof (code_element *) *
(c->numEntries + 1));
for (int ii = 0; ii < c->numEntries; ii++) {
foo[ii] = c->cb[ii]; /* copy all pointers */
}
foo[c->numEntries] = (code_element *) g_malloc (sizeof (code_element));
if (c->numEntries)
g_free (c->cb);
c->cb = foo;
for (n = 0; n < numChannels; n++) {
c->cb[c->numEntries]->learnHigh[n] = high[n];
c->cb[c->numEntries]->learnLow[n] = low[n];
c->cb[c->numEntries]->max[n] = *(p + n);
c->cb[c->numEntries]->min[n] = *(p + n);
}
c->cb[c->numEntries]->t_last_update = c->t;
c->cb[c->numEntries]->stale = 0;
c->numEntries += 1;
}
/* SLOWLY ADJUST LEARNING BOUNDS */
for (n = 0; n < numChannels; n++) {
if (c->cb[i]->learnHigh[n] < high[n])
c->cb[i]->learnHigh[n] += 1;
if (c->cb[i]->learnLow[n] > low[n])
c->cb[i]->learnLow[n] -= 1;
}
return (i);
}
/*
int clear_stale_entries(codeBook &c)
During learning, after you've learned for some period of time,
periodically call this to clear out stale codebook entries
c Codebook to clean up
Return
number of entries cleared
*/
int
clear_stale_entries (codeBook * c)
{
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int staleThresh = c->t >> 1;
int *keep = (int *) g_malloc (sizeof (int) * (c->numEntries));
int keepCnt = 0;
code_element **foo;
int k;
int numCleared;
/* SEE WHICH CODEBOOK ENTRIES ARE TOO STALE */
for (int i = 0; i < c->numEntries; i++) {
if (c->cb[i]->stale > staleThresh)
keep[i] = 0; /* Mark for destruction */
else {
keep[i] = 1; /* Mark to keep */
keepCnt += 1;
}
}
/* KEEP ONLY THE GOOD */
c->t = 0; /* Full reset on stale tracking */
foo = (code_element **) g_malloc (sizeof (code_element *) * keepCnt);
k = 0;
for (int ii = 0; ii < c->numEntries; ii++) {
if (keep[ii]) {
foo[k] = c->cb[ii];
/* We have to refresh these entries for next clearStale */
foo[k]->t_last_update = 0;
k++;
}
}
/* CLEAN UP */
g_free (keep);
g_free (c->cb);
c->cb = foo;
numCleared = c->numEntries - keepCnt;
c->numEntries = keepCnt;
return (numCleared);
}
/*
uchar background_diff( uchar *p, codeBook &c,
int minMod, int maxMod)
Given a pixel and a codebook, determine if the pixel is
covered by the codebook
p Pixel pointer (YUV interleaved)
c Codebook reference
numChannels Number of channels we are testing
maxMod Add this (possibly negative) number onto
max level when determining if new pixel is foreground
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minMod Subtract this (possibly negative) number from
min level when determining if new pixel is foreground
NOTES:
minMod and maxMod must have length numChannels,
e.g. 3 channels => minMod[3], maxMod[3]. There is one min and
one max threshold per channel.
Return
0 => background, 255 => foreground
*/
unsigned char
background_diff (unsigned char *p, codeBook * c, int numChannels,
int *minMod, int *maxMod)
{
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int matchChannel;
/* SEE IF THIS FITS AN EXISTING CODEWORD */
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int i;
for (i = 0; i < c->numEntries; i++) {
matchChannel = 0;
for (int n = 0; n < numChannels; n++) {
if ((c->cb[i]->min[n] - minMod[n] <= *(p + n)) &&
(*(p + n) <= c->cb[i]->max[n] + maxMod[n])) {
matchChannel++; /* Found an entry for this channel */
} else {
break;
}
}
if (matchChannel == numChannels) {
break; /* Found an entry that matched all channels */
}
}
if (i >= c->numEntries)
return (255);
return (0);
}
/*
void find_connected_components(IplImage *mask, int poly1_hull0,
float perimScale, int *num,
CvRect *bbs, CvPoint *centers)
This cleans up the foreground segmentation mask derived from calls
to backgroundDiff
mask Is a grayscale (8-bit depth) âœraw❠mask image that
will be cleaned up
OPTIONAL PARAMETERS:
poly1_hull0 If set, approximate connected component by
(DEFAULT) polygon, or else convex hull (0)
perimScale Len = image (width+height)/perimScale. If contour
len < this, delete that contour (DEFAULT: 4)
num Maximum number of rectangles and/or centers to
return; on return, will contain number filled
(DEFAULT: NULL)
bbs Pointer to bounding box rectangle vector of
length num. (DEFAULT SETTING: NULL)
centers Pointer to contour centers vector of length
num (DEFAULT: NULL)
*/
/* Approx.threshold - the bigger it is, the simpler is the boundary */
#define CVCONTOUR_APPROX_LEVEL 1
/* How many iterations of erosion and/or dilation there should be */
#define CVCLOSE_ITR 1
static void
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find_connected_components (Mat mask, int poly1_hull0, float perimScale)
{
/* Just some convenience variables */
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const Scalar CVX_WHITE = CV_RGB (0xff, 0xff, 0xff);
//const Scalar CVX_BLACK = CV_RGB (0x00, 0x00, 0x00);
int idx = 0;
/* CLEAN UP RAW MASK */
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morphologyEx (mask, mask, MORPH_OPEN, Mat (), Point (-1, -1), CVCLOSE_ITR);
morphologyEx (mask, mask, MORPH_CLOSE, Mat (), Point (-1, -1), CVCLOSE_ITR);
/* FIND CONTOURS AROUND ONLY BIGGER REGIONS */
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std::vector < std::vector < Point > >contours;
std::vector < std::vector < Point > >to_draw;
std::vector < Vec4i > hierarchy;
findContours (mask, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE,
Point (0, 0));
if (contours.size () == 0)
return;
for (; idx >= 0; idx = hierarchy[idx][0]) {
const std::vector < Point > &c = contours[idx];
double len = fabs (contourArea (Mat (c)));
double q = (mask.size ().height + mask.size ().width) / perimScale;
if (len >= q) {
std::vector < Point > c_new;
if (poly1_hull0) {
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approxPolyDP (c, c_new, CVCONTOUR_APPROX_LEVEL, (hierarchy[idx][2] < 0
&& hierarchy[idx][3] < 0));
} else {
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convexHull (c, c_new, true, true);
}
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to_draw.push_back (c_new);
}
}
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mask.setTo (Scalar::all (0));
if (to_draw.size () > 0) {
drawContours (mask, to_draw, -1, CVX_WHITE, FILLED);
}
}
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#endif /*ifdef CODE_FROM_OREILLY_BOOK */
int
run_mog_iteration (GstSegmentation * filter)
{
/*
BackgroundSubtractorMOG [1], Gaussian Mixture-based Background/Foreground
Segmentation Algorithm. OpenCV MOG implements the algorithm described in [2].
[1] http://opencv.itseez.com/modules/video/doc/motion_analysis_and_object_tracking.html#backgroundsubtractormog
[2] P. KadewTraKuPong and R. Bowden, "An improved adaptive background
mixture model for real-time tracking with shadow detection", Proc. 2nd
European Workshop on Advanced Video-Based Surveillance Systems, 2001
*/
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filter->mog->apply (filter->cvYUV, filter->cvFG, filter->learning_rate);
return (0);
}
int
run_mog2_iteration (GstSegmentation * filter)
{
/*
BackgroundSubtractorMOG2 [1], Gaussian Mixture-based Background/Foreground
segmentation algorithm. OpenCV MOG2 implements the algorithm described in
[2] and [3].
[1] http://opencv.itseez.com/modules/video/doc/motion_analysis_and_object_tracking.html#backgroundsubtractormog2
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[2] Z.Zivkovic, "Improved adaptive Gaussian mixture model for background
subtraction", International Conference Pattern Recognition, UK, August, 2004.
[3] Z.Zivkovic, F. van der Heijden, "Efficient Adaptive Density Estimation per
Image Pixel for the Task of Background Subtraction", Pattern Recognition
Letters, vol. 27, no. 7, pages 773-780, 2006.
*/
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filter->mog2->apply (filter->cvYUV, filter->cvFG, filter->learning_rate);
return (0);
}