GraphCut & GrabCut
图像分割一直是图像处理中一项棘手的问题。图像分割算法从大的方面讲可以分为两类：
1 全自动图像分割：一般采用聚类算法来最大化前景与背景的差。
2 用户互动式图像分割：用户提供前景和背景的种子，然后对前景背景建立概率分布模型。
而GraphCut和GrabCut就是属于第二类图像分割算法。
没有用GraphCut的源码。opencv有GrabCut的一个例程。我稍作了一点操作上的修改而已。这个算法的效率不是很高，迭代了45次左右。刚开始没有添加种子点，后面需要。会丢失一些细节的（当然）。
源码：
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include
using namespace std;
using namespace cv;
static void help()
{
cout << "\nThis program demonstrates GrabCut segmentation -- select an object in a region\n"
"and then grabcut will attempt to segment it out.\n"
"Call:\n"
"./grabcut \n"
"\nSelect a rectangular area around the object you want to segment\n" <<
"\nHot keys: \n"
"\tESC - quit the program\n"
"\tr - restore the original image\n"
"\tn - next iteration\n"
"\n"
"\tleft mouse button - set rectangle\n"
"\n"
"\tCTRL+left mouse button - set GC_BGD pixels\n"
"\tSHIFT+left mouse button - set CG_FGD pixels\n"
"\n"
"\tCTRL+right mouse button - set GC_PR_BGD pixels\n"
"\tSHIFT+right mouse button - set CG_PR_FGD pixels\n" << endl;
}
//GC_BGD = 0, //!< an obvious background pixels
//GC_FGD = 1, //!< an obvious foreground (object) pixel
//GC_PR_BGD = 2, //!< a possible background pixel
//GC_PR_FGD = 3 //!< a possible foreground pixel
const Scalar RED = Scalar(0,0,255);
const Scalar PINK = Scalar(230,130,255);
const Scalar BLUE = Scalar(255,0,0);
const Scalar LIGHTBLUE = Scalar(255,255,160);
const Scalar GREEN = Scalar(0,255,0);
Mat resSave;
//CTRL键
const int BGD_KEY = CV_EVENT_FLAG_CTRLKEY;
//SHIFT键
const int FGD_KEY = CV_EVENT_FLAG_SHIFTKEY;
//产生一个mask comMask中为1或3的会在binMask中保留
static void getBinMask( const Mat& comMask, Mat& binMask )
{
if( comMask.empty() || comMask.type()!=CV_8UC1 )
CV_Error( CV_StsBadArg, "comMask is empty or has incorrect type (not CV_8UC1)" );
if( binMask.empty() || binMask.rows!=comMask.rows || binMask.cols!=comMask.cols )
binMask.create( comMask.size(), CV_8UC1 );
binMask = comMask & 1;
}
class GCApplication
{
public:
//NOT_SET代表还没有开始绘图
//IN_PROCESS代表正在绘图
//SET代表绘图完成
enum{ NOT_SET = 0, IN_PROCESS = 1, SET = 2 };
static const int radius = 2;
static const int thickness = -1;
void reset();
void setImageAndWinName( const Mat& _image, const string& _winName );
void showImage() const;
void mouseClick( int event, int x, int y, int flags, void* param );
int nextIter();
void saveimg();
int getIterCount() const { return iterCount; }
void clearRec();
private:
void setRectInMask();
void setLblsInMask( int flags, Point p, bool isPr );
//这里的窗口名称和图片名称都是地址
const string* winName;
const Mat* image;
Mat mask;
Mat bgdModel, fgdModel;
//表示绘制的矩形、确定、可能的景的状态
uchar rectState, lblsState, prLblsState;
bool isInitialized;
Rect rect;
vector fgdPxls, bgdPxls, prFgdPxls, prBgdPxls;
int iterCount;
};
void GCApplication::clearRec(){
rectangle( resSave, Point( rect.x, rect.y ), Point(rect.x + rect.width, rect.y + rect.height ), Scalar(0, 0, 0), 2);
}
void GCApplication::saveimg(){
imwrite("newme.jpeg", resSave);
}
void GCApplication::reset()
{
if( !mask.empty() )
mask.setTo(Scalar::all(GC_BGD));
bgdPxls.clear(); fgdPxls.clear();
prBgdPxls.clear(); prFgdPxls.clear();
isInitialized = false;
rectState = NOT_SET;
lblsState = NOT_SET;
prLblsState = NOT_SET;
iterCount = 0;
}
void GCApplication::setImageAndWinName( const Mat& _image, const string& _winName )
{
if( _image.empty() || _winName.empty() )
return;
image = &_image;
winName = &_winName;
mask.create( image->size(), CV_8UC1);
reset();
}
void GCApplication::showImage() const
{
if( image->empty() || winName->empty())
return;
Mat res;
Mat binMask;
if( !isInitialized )
image->copyTo( res );
else
{
//如果有掩膜，掩膜的部分不会改变
getBinMask( mask, binMask );
image->copyTo( res, binMask );
}
vector::const_iterator it;
//背景是蓝色的 不确定的背景是浅蓝
//前景是红色的 不确定的前景是粉红
for( it = bgdPxls.begin(); it != bgdPxls.end(); ++it )
circle( res, *it, radius, BLUE, thickness );
for( it = fgdPxls.begin(); it != fgdPxls.end(); ++it )
circle( res, *it, radius, RED, thickness );
for( it = prBgdPxls.begin(); it != prBgdPxls.end(); ++it )
circle( res, *it, radius, LIGHTBLUE, thickness );
for( it = prFgdPxls.begin(); it != prFgdPxls.end(); ++it )
circle( res, *it, radius, PINK, thickness );
//每一次imshow之前，res都更新了，变成了原图（如果没有mask）
//这样就有了矩形框的更新，而且，前一次的矩形框会消失
//因为矩形框是直接在原图上画的！！！！！
//终于找到了这个方法。
if( rectState == IN_PROCESS || rectState == SET )
rectangle( res, Point( rect.x, rect.y ), Point(rect.x + rect.width, rect.y + rect.height ), GREEN, 2);
imshow( *winName, res );
res.copyTo(resSave);
return;
}
void GCApplication::setRectInMask()
{
assert( !mask.empty() );
//先全0
mask.setTo( GC_BGD );
rect.x = max(0, rect.x);
rect.y = max(0, rect.y);
rect.width = min(rect.width, image->cols-rect.x);
rect.height = min(rect.height, image->rows-rect.y);
(mask(rect)).setTo( Scalar(GC_PR_FGD) );
}
void GCApplication::setLblsInMask( int flags, Point p, bool isPr )
{
vector *bpxls, *fpxls;
uchar bvalue, fvalue;
if( !isPr )
{
//取地址 bpxls和bgdPxls同时改变
//在画完矩形之前 这个Vector都是空的
//画完之后开始给景打标签，Vector不为空
bpxls = &bgdPxls;
fpxls = &fgdPxls;
bvalue = GC_BGD;
fvalue = GC_FGD;
}
else
{
bpxls = &prBgdPxls;
fpxls = &prFgdPxls;
bvalue = GC_PR_BGD;
fvalue = GC_PR_FGD;
}
//记住这种用法 代表flags==BGD_KEY CTRL
if( flags & BGD_KEY )
{
//保存
bpxls->push_back(p);
//绘圆
circle( mask, p, radius, bvalue, thickness );
}
//SHIFT
if( flags & FGD_KEY )
{
fpxls->push_back(p);
circle( mask, p, radius, fvalue, thickness );
}
}
void GCApplication::mouseClick( int event, int x, int y, int flags, void* )
{
// TODO add bad args check
switch( event )
{
case CV_EVENT_LBUTTONDOWN: // set rect or GC_BGD(GC_FGD) labels
{
bool isb = (flags & BGD_KEY) != 0,
isf = (flags & FGD_KEY) != 0;
if( rectState == NOT_SET && !isb && !isf )
{
//没有按下CTRL SHIFT; 绘制矩形
rectState = IN_PROCESS;
rect = Rect( x, y, 1, 1 );
}
//矩形画完！了 标前后景
if ( (isb || isf) && rectState == SET )
lblsState = IN_PROCESS;
}
break;
case CV_EVENT_RBUTTONDOWN: // set GC_PR_BGD(GC_PR_FGD) labels
{
bool isb = (flags & BGD_KEY) != 0,
isf = (flags & FGD_KEY) != 0;
if ( (isb || isf) && rectState == SET )
prLblsState = IN_PROCESS;
}
break;
case CV_EVENT_LBUTTONUP:
if( rectState == IN_PROCESS )
{
rect = Rect( Point(rect.x, rect.y), Point(x,y) );
rectState = SET;
setRectInMask();
//这个时候还没有标前后景
assert( bgdPxls.empty() && fgdPxls.empty() && prBgdPxls.empty() && prFgdPxls.empty() );
showImage();
}
if( lblsState == IN_PROCESS )
{
setLblsInMask(flags, Point(x,y), false);
lblsState = SET;
showImage();
}
break;
case CV_EVENT_RBUTTONUP:
if( prLblsState == IN_PROCESS )
{
setLblsInMask(flags, Point(x,y), true);
prLblsState = SET;
showImage();
}
break;
case CV_EVENT_MOUSEMOVE:
if( rectState == IN_PROCESS )
{
rect = Rect( Point(rect.x, rect.y), Point(x,y) );
assert( bgdPxls.empty() && fgdPxls.empty() && prBgdPxls.empty() && prFgdPxls.empty() );
showImage();
}
else if( lblsState == IN_PROCESS )
{
setLblsInMask(flags, Point(x,y), false);
showImage();
}
else if( prLblsState == IN_PROCESS )
{
setLblsInMask(flags, Point(x,y), true);
showImage();
}
break;
}
}
int GCApplication::nextIter()
{
if( isInitialized ) {
grabCut(*image, mask, rect, bgdModel, fgdModel, 1);
}
else
{
if( rectState != SET )
return iterCount;
if( lblsState == SET || prLblsState == SET )
grabCut( *image, mask, rect, bgdModel, fgdModel, 1, GC_INIT_WITH_MASK );
else
grabCut( *image, mask, rect, bgdModel, fgdModel, 1, GC_INIT_WITH_RECT );
//mask会保存图片?
//mask.copyTo(Newme);
isInitialized = true;
}
iterCount++;
//每次迭代以前清空之前的种子像素，会有新的mask
bgdPxls.clear(); fgdPxls.clear();
prBgdPxls.clear(); prFgdPxls.clear();
return iterCount;
}
GCApplication gcapp;
static void on_mouse( int event, int x, int y, int flags, void* param )
{
gcapp.mouseClick( event, x, y, flags, param );
}
int main( int argc, char** argv )
{
// if( argc!=2 )
// {
// help();
// return 1;
// }
// string filename = argv[1];
string filename = "../me.jpeg";
if( filename.empty() )
{
cout << "\ncouldn't read in " << argv[1] << endl;
return 1;
}
Mat image = imread( filename, 1 );
resize(image, image, Size(int(image.cols/1.3), int(image.rows/1.3)), NULL, NULL, 1);
if( image.empty() )
{
cout << "\n couldn't read image filename " << filename << endl;
return 1;
}
help();
const string winName = "image";
//如果不是autosize，坐标点会出现问题诶...
namedWindow( winName, WINDOW_AUTOSIZE );
setMouseCallback( winName, on_mouse, 0 );
gcapp.setImageAndWinName( image, winName );
gcapp.showImage();
for(;;)
{
int c = waitKey(0);
switch( (char) c )
{
//16进制27：Esc
case '\x1b': {
cout << "Exiting ..." << endl;
goto exit_main;
}
case 'r': {
cout << endl;
gcapp.reset();
gcapp.showImage();
}
break;
case 'n': {
int iterCount = gcapp.getIterCount();
cout << "<" << iterCount << "... ";
int newIterCount = gcapp.nextIter();
if (newIterCount > iterCount) {
gcapp.showImage();
cout << iterCount << ">" << endl;
} else {
cout << "rect must be determined>" << endl;
}
}
break;
case 's': {
//把矩形去掉
gcapp.clearRec();
cout<<"saving"<