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Background.cpp
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Background.cpp
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/*----------------------------------------------------------------------------*/
/* Copyright (C) 2015 Alexandre Campo */
/* */
/* This file is part of USE Tracker. */
/* */
/* USE Tracker is free software: you can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation, either version 3 of the License, or */
/* (at your option) any later version. */
/* */
/* USE Tracker 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 General Public License for more details. */
/* */
/* You should have received a copy of the GNU General Public License */
/* along with USE Tracker. If not, see <http://www.gnu.org/licenses/>. */
/*----------------------------------------------------------------------------*/
#include "Background.h"
#include <opencv2/imgproc/imgproc.hpp>
using namespace cv;
using namespace std;
Mat CalculateBackgroundMedian (Capture* capture, float startTime, float endTime, unsigned int framesCount, unsigned char lowThreshold, unsigned char highThreshold)
{
int width = capture->width;
int height = capture->height;
Mat background = Mat::zeros(height, width, CV_8UC3);
// do not calc bg for an image...
if (capture->type == Capture::IMAGE) return background;
// if endtime is very small, consider that we want to use the entire capture duration. In case
// this a webcam, give up calculation
if (endTime < 0.01)
{
if (capture->type == Capture::VIDEO || capture->type == Capture::MULTI_VIDEO)
{
endTime = ((double)capture->GetFrameCount()) / capture->fps;
}
else
return background;
}
cerr << "Calculating median background" << endl;
capture->Stop();
capture->Play();
unsigned char* samples = new unsigned char [framesCount * width * height * 3];
unsigned int readCount = 0;
unsigned int index = 0;
float intervalTime = (endTime - startTime) / framesCount;
while (readCount < framesCount)
{
capture->GetFrame (startTime + intervalTime * readCount);
double msgTime = capture->GetTime();
cerr << "using frame at time " << msgTime << endl;
if (capture->frame.empty())
break;
for (int y = 0; y < height; y++)
{
unsigned char* frameRow = capture->frame.ptr<unsigned char>(y);
for (int x = 0; x < width; x++)
{
samples[index++] = frameRow[x * 3];
samples[index++] = frameRow[x * 3 + 1];
samples[index++] = frameRow[x * 3 + 2];
}
}
readCount++;
}
capture->Stop();
// ok finished extracting frames from movie
// automatically calculate background
// for every pixel :
unsigned char* r = new unsigned char (readCount);
unsigned char* g = new unsigned char (readCount);
unsigned char* b = new unsigned char (readCount);
int index2 = 0;
for (int y = 0; y < height; y++)
{
unsigned char* bgRow = background.ptr<unsigned char>(y);
for (int x = 0; x < width; x++)
{
// gather some stats in a buffer
int idx = index2;
for (unsigned int i = 0; i < readCount; i++)
{
r[i] = samples[idx];
g[i] = samples[idx + 1];
b[i] = samples[idx + 2];
idx += width * height * 3;
}
index2 += 3;
// now find out the most representative values
unsigned char bgr = 127, bgg = 127, bgb = 127;
unsigned long bgrCount = 0, bggCount = 0, bgbCount = 0;
unsigned long hist[256];
memset (hist, 0, sizeof (unsigned long) * 256);
for (unsigned int i = 0; i < readCount; i++) hist[r[i]]++;
for (unsigned int i = lowThreshold; i <= highThreshold; i++)
{
if (hist[i] > bgrCount)
{
bgrCount = hist[i]; bgr = i;
}
}
// found no pixels due to thresholds, repeat to have some meaningful value
if (bgrCount == 0)
{
for (unsigned int i = 0; i <= 255; i++)
{
if (hist[i] > bgrCount)
{
bgrCount = hist[i]; bgr = i;
}
}
}
memset (hist, 0, sizeof (unsigned long) * 256);
for (unsigned int i = 0; i < readCount; i++) hist[g[i]]++;
for (unsigned int i = lowThreshold; i <= highThreshold; i++)
{
if (hist[i] > bggCount)
{
bggCount = hist[i]; bgg = i;
}
}
// found no pixels due to thresholds, repeat to have some meaningful value
if (bggCount == 0)
{
for (unsigned int i = 0; i <= 255; i++)
{
if (hist[i] > bggCount)
{
bggCount = hist[i]; bgg = i;
}
}
}
memset (hist, 0, sizeof (unsigned long) * 256);
for (unsigned int i = 0; i < readCount; i++) hist[b[i]]++;
for (unsigned int i = lowThreshold; i <= highThreshold; i++)
{
if (hist[i] > bgbCount)
{
bgbCount = hist[i]; bgb = i;
}
}
// found no pixels due to thresholds, repeat to have some meaningful value
if (bgbCount == 0)
{
for (unsigned int i = 0; i <= 255; i++)
{
if (hist[i] > bgbCount)
{
bgbCount = hist[i]; bgb = i;
}
}
}
// now go through the triplets and select the one that is the closest from this evaluation
unsigned int mindist = 1000000;
unsigned char fr = 0, fg = 0, fb = 0;
for (unsigned int i = 0; i < readCount; i++)
{
unsigned int luminance = int(r[i]) + int(g[i]) + int(b[i]);
unsigned int dist = abs(int(r[i]) - int(bgr)) + abs(int(g[i]) - int(bgg)) + abs(int(b[i]) - int(bgb));
if (dist < mindist && luminance >= (lowThreshold * 3) && luminance <= (highThreshold * 3))
{
mindist = dist;
fr = r[i];
fg = g[i];
fb = b[i];
}
}
// relax if threshold does not yield results...
if (mindist == 1000000)
{
for (unsigned int i = 0; i < readCount; i++)
{
unsigned int dist = abs(int(r[i]) - int(bgr)) + abs(int(g[i]) - int(bgg)) + abs(int(b[i]) - int(bgb));
if (dist < mindist)
{
mindist = dist;
fr = r[i];
fg = g[i];
fb = b[i];
}
}
}
// and at last record result in the bg buffer
bgRow[x*3] = fr;
bgRow[x*3+1] = fg;
bgRow[x*3+2] = fb;
}
}
delete[] r;
delete[] g;
delete[] b;
delete[] samples;
cerr << "Background calculated" << endl;
return background;
}
Mat CalculateBackgroundMean (Capture* capture, float startTime, float endTime, unsigned int framesCount, unsigned char lowThreshold, unsigned char highThreshold)
{
int width = capture->width;
int height = capture->height;
Mat background = Mat::zeros(height, width, CV_8UC3);
Mat accu = Mat::zeros(height, width, CV_32FC3);
// do not calc bg for an image...
if (capture->type == Capture::IMAGE) return background;
// if endtime is very small, consider that we want to use the entire capture duration. In case
// this a webcam, give up calculation
if (endTime < 0.01)
{
if (capture->type == Capture::VIDEO || capture->type == Capture::MULTI_VIDEO)
{
endTime = ((double)capture->GetFrameCount()) / capture->fps;
}
else
return background;
}
cerr << "Calculating mean background" << endl;
capture->Stop();
capture->Play();
unsigned int readCount = 0;
float intervalTime = (endTime - startTime) / framesCount;
while (readCount < framesCount)
{
capture->GetFrame(startTime + intervalTime * readCount);
double msgTime = capture->GetTime();
cerr << "using frame at time " << msgTime << endl;
if (capture->frame.empty())
break;
cv::accumulate (capture->frame, accu);
readCount++;
}
accu /= readCount;
accu.convertTo(background,CV_8UC3);
cerr << "Background calculated" << endl;
capture->Stop();
return background;
}