【OpenCV】使用floodfill()實現PhotoShop魔棒功能

在OpenCV中看到一個很有意思的函數：floodfill()

使用給定顏色填充一個聯通的區域

C++: int floodFill(InputOutputArray image, Point seedPoint, 
Scalar newVal, Rect* rect=0, Scalar loDiff=Scalar(), 
Scalar upDiff=Scalar(), int flags=4 )

一個簡單的例子：

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

#include <iostream>

using namespace cv;
using namespace std;

//floodfill()
//Fills a connected component with the given color.

static void help()
{
cout << "\nThis program demonstrated the floodFill() function\n"
"Call:\n"
"./ffilldemo [image_name -- Default: fruits.jpg]\n" << endl;

cout << "Hot keys: \n"
"\tESC - quit the program\n"
"\tc - switch color/grayscale mode\n"
"\tm - switch mask mode\n"
"\tr - restore the original image\n"
"\ts - use null-range floodfill\n"
"\tf - use gradient floodfill with fixed(absolute) range\n"
"\tg - use gradient floodfill with floating(relative) range\n"
"\t4 - use 4-connectivity mode\n"
"\t8 - use 8-connectivity mode\n" << endl;
}

Mat image0, image, gray, mask;
int ffillMode = 1;
int loDiff = 20, upDiff = 20;
int connectivity = 4;
int isColor = true;
bool useMask = false;
int newMaskVal = 255;

static void onMouse( int event, int x, int y, int, void* )
{
if( event != CV_EVENT_LBUTTONDOWN )
return;

Point seed = Point(x,y);
int lo = ffillMode == 0 ? 0 : loDiff;
int up = ffillMode == 0 ? 0 : upDiff;
int flags = connectivity + (newMaskVal << 8) +
(ffillMode == 1 ? CV_FLOODFILL_FIXED_RANGE : 0);
int b = (unsigned)theRNG() & 255;
int g = (unsigned)theRNG() & 255;
int r = (unsigned)theRNG() & 255;
Rect ccomp;

Scalar newVal = isColor ? Scalar(b, g, r) : Scalar(r*0.299 + g*0.587 + b*0.114);
Mat dst = isColor ? image : gray;
int area;

if( useMask )
{
threshold(mask, mask, 1, 128, CV_THRESH_BINARY);
area = floodFill(dst, mask, seed, newVal, &ccomp, Scalar(lo, lo, lo),
Scalar(up, up, up), flags);
imshow( "mask", mask );
}
else
{
area = floodFill(dst, seed, newVal, &ccomp, Scalar(lo, lo, lo),
Scalar(up, up, up), flags);
}

imshow("image", dst);
cout << area << " pixels were repainted\n";
}

int main( )
{
char* filename="0.png";
image0 = imread(filename, 1);

if( image0.empty() )
{
cout << "Image empty. Usage: ffilldemo <image_name>\n";
return 0;
}
help();
image0.copyTo(image);
cvtColor(image0, gray, CV_BGR2GRAY);
mask.create(image0.rows+2, image0.cols+2, CV_8UC1);

namedWindow( "image", 0 );
createTrackbar( "lo_diff", "image", &loDiff, 255, 0 );
createTrackbar( "up_diff", "image", &upDiff, 255, 0 );

setMouseCallback( "image", onMouse, 0 );

for(;;)
{
imshow("image", isColor ? image : gray);

int c = waitKey(0);
if( (c & 255) == 27 )
{
cout << "Exiting ...\n";
break;
}
switch( (char)c )
{
case 'c':
if( isColor )
{
cout << "Grayscale mode is set\n";
cvtColor(image0, gray, CV_BGR2GRAY);
mask = Scalar::all(0);
isColor = false;
}
else
{
cout << "Color mode is set\n";
image0.copyTo(image);
mask = Scalar::all(0);
isColor = true;
}
break;
case 'm':
if( useMask )
{
destroyWindow( "mask" );
useMask = false;
}
else
{
namedWindow( "mask", 0 );
mask = Scalar::all(0);
imshow("mask", mask);
useMask = true;
}
break;
case 'r':
cout << "Original image is restored\n";
image0.copyTo(image);
cvtColor(image, gray, CV_BGR2GRAY);
mask = Scalar::all(0);
break;
case 's':
cout << "Simple floodfill mode is set\n";
ffillMode = 0;
break;
case 'f':
cout << "Fixed Range floodfill mode is set\n";
ffillMode = 1;
break;
case 'g':
cout << "Gradient (floating range) floodfill mode is set\n";
ffillMode = 2;
break;
case '4':
cout << "4-connectivity mode is set\n";
connectivity = 4;
break;
case '8':
cout << "8-connectivity mode is set\n";
connectivity = 8;
break;
}
}

return 0;
}

點擊圖標改變圖像中的連圖區域的顏色：

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Ubuntu Linux下安裝OpenCV2.4.1所需包 http://www.linuxidc.com/Linux/2012-08/68184.htm

Ubuntu 12.04 安裝 OpenCV2.4.2 http://www.linuxidc.com/Linux/2012-09/70158.htm

CentOS下OpenCV無法讀取視頻文件 http://www.linuxidc.com/Linux/2011-07/39295.htm

Ubuntu 12.04下安裝OpenCV 2.4.5總結 http://www.linuxidc.com/Linux/2013-06/86704.htm

Ubuntu 10.04中安裝OpenCv2.1九步曲 http://www.linuxidc.com/Linux/2010-09/28678.htm

基於QT和OpenCV的人臉識別系統 http://www.linuxidc.com/Linux/2011-11/47806.htm

[翻譯]Ubuntu 14.04, 13.10 下安裝 OpenCV 2.4.9 http://www.linuxidc.com/Linux/2014-12/110045.htm

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OpenCV的詳細介紹：請點這裡
OpenCV的下載地址：請點這裡