【OpenCV】使用floodfill()實現PhotoShop魔棒功能

轉自：http://blog.csdn.net/xiaowei_cqu/article/details/8987387

在OpenCV中看到一個很有意思的函式：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;
}

點選圖示改變影象中的連圖區域的顏色：

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