Color filtering GUI using openCV
From MABL_Wiki
This article will help to set up a simple GUI for color filtering using C++ and openCV. This article was written in the assumption that you have the basic understanding of C++ and image processing.
Contents |
Installing openCV
The following link will help you to donwload and install openCV http://opencv.willowgarage.com/wiki/InstallGuide
Source Code
- Code
this is the source code for GUI openCV:
//##using C++ library##
#include <iostream>
using namespace std;
#include <stdlib.h>
//##using openCV library##
#include "cv.h"
#include "highgui.h"
#include "cxcore.h"
using namespace cv;
int main ( int argc, char **argv ) //--------------MAIN BODY---------------
{
VideoCapture webCam(0); // video source for webcam
webCam.set(CV_CAP_PROP_FRAME_WIDTH,640);
webCam.set(CV_CAP_PROP_FRAME_HEIGHT,480);
// slices matrcies that hold H,S and V
vector<Mat> slices;
// Cross Element for Erosion/Dilation
Mat cross = getStructuringElement(MORPH_CROSS, Size(5,5));
// create matrices to hold image
Mat camImage; // raw image from webcam
Mat blurImage; // blur image
Mat hsvImage; // hsv image
Mat hue; // hue channel
Mat hue1; // Hue upper bound
Mat hue2; // Hue lower bound
Mat hue3; // hue color filtering
Mat sat; // Sat channel
Mat sat1; // Sat upper bound
Mat sat2; // sat lower bound
Mat sat3; // sat color filtering
Mat val; // Val channel
Mat val1; // Val upper bound
Mat val2; // Val lower bound
Mat val3; // Val color filtering
Mat erd; // Erosion Image
Mat dia; // dialate image
Mat HnS; // sat and hue channel
Mat HSV; // HSV color fiter detected
// slide bar values
int HuethresH =0,
HuethresL =0,
SatthresL =0,
SatthresH = 0,
ValthresL =0,
ValthresH = 0,
erosionCount = 1,
blurSize = 3;
// new window
cvNamedWindow("Color Tune",CV_WINDOW_NORMAL);
// make tune bar
cvCreateTrackbar( "Hue UpperT","Color Tune", &HuethresH, 255, 0 );
cvCreateTrackbar ("Hue LowerT","Color Tune", &HuethresL,255, 0);
cvCreateTrackbar( "Sat UpperT","Color Tune", &SatthresH, 255, 0 );
cvCreateTrackbar( "Sat LowerT","Color Tune", &SatthresL, 255, 0 );
cvCreateTrackbar( "Val UpperT","Color Tune", &ValthresH, 255, 0 );
cvCreateTrackbar( "Val LowerT","Color Tune", &ValthresL, 255, 0 );
cvCreateTrackbar ("EroTime","Color Tune", &erosionCount,15, 0);
cvCreateTrackbar ("BlurSize","Color Tune", &blurSize,15, 0);
// check blurSize bound
if(blurSize == 0)
blurSize = 1; //reset blurSize
// get and display webcam image
while(1)
{
// get new image over and over from webcam
webCam >> camImage;
// check blurSize bound
if(blurSize == 0)
blurSize = 1; //reset blurSize
// blur image
//blur(camImage, blurImage, Size(11,11));
blur(camImage, blurImage, Size(blurSize,blurSize));
// conver raw image to hsv
cvtColor (camImage, hsvImage, CV_RGB2HSV);
// check blurSize bound
if(blurSize == 0)
blurSize = 1; //reset blurSize
blur(hsvImage, hsvImage, Size(blurSize,blurSize));
//blur(hsvImage, hsvImage, Size(5,5));
// split image to H,S and V images
split(hsvImage,slices);
slices[0].copyTo (hue); // get the hue channel
slices[1].copyTo(sat); // get the sat channel
slices[2].copyTo(val); // get the V channel
//apply threshold HUE upper/lower for color range
threshold (hue,hue1,HuethresL,255, CV_THRESH_BINARY); // get lower bound
threshold (hue, hue2,HuethresH,255, CV_THRESH_BINARY_INV); // get upper bound
hue3 = hue1 &hue2; // multiply 2 matrix to get the color range
// apply thresshold for Sat channel
threshold (sat,sat1,SatthresL,255, CV_THRESH_BINARY); // get lower bound
threshold (sat, sat2,SatthresH,255, CV_THRESH_BINARY_INV); // get upper bound
sat3 = sat1 & sat2; // multiply 2 matrix to get the color range
// apply thresshold for Val channel
threshold (val,val1,SatthresL,255, CV_THRESH_BINARY); // get lower bound
threshold (val, val2,SatthresH,255, CV_THRESH_BINARY_INV); // get upper bound
val3 = val1 & val2; // multiply 2 matrix to get the color range
// combine sat and hue filter together
HnS = sat3 & hue3;
// erode and dialation to reduce noise
erode(HnS,erd,cross,Point(-1,-1),erosionCount); // do erode
dilate(HnS,dia,cross,Point(-1,-1),erosionCount);// do dialate
// combine sat, val and hue filter together
HSV = sat3 & hue3 & val3;
// erode and dialation to reduce noise
erode(HSV,erd,cross,Point(-1,-1),erosionCount); // do erode
dilate(HSV,dia,cross,Point(-1,-1),erosionCount); // do dialate
// display image over and over
imshow("Webcam Orignal", camImage);
//imshow("Blur", blurImage);
//imshow("HSV Image", hsvImage);
//imshow("Hue channel",hue);
//imshow("Lower bound",hue1);
//imshow("Upper bound", hue2);
//imshow("L channel", Val);
//imshow("Color detected", hue3);
//imshow("Erosion",erd);
imshow("Hue color",hue3);
//imshow("Sat channel",sat);
imshow("Sat color",sat3);
//imshow("Val color",val3);
imshow("Sat and Hue",HnS);
imshow("HSV",HSV);
// Pause for highgui to process image painting
cvWaitKey(5);
}
//------CLEAN UP-------
cvDestroyAllWindows();
}
Using the GUI
The image bellow show the color tune bar GUI.
Adjust each channel individually. For example, you want to find the green color in the hue channel. You should adjust the hue upper thresh and lower thresh only until you see only the green color show up in the "Hue Channel" window. And do this for other channels as well.
Using the erode time and blur size to help you cancel some background noise as well. Blur size must be an odd number.
The final image will be the combination of three channels and it looks like this
As you can see I reduce a lot of noise and get the solid green color.
When not using the V channel
Notice: be really careful when you use the V channel. It depends on the light intensity so if you are in the room that has unevenly light source do not use V channel otherwise your color filtering will not work well. To eliminate the V channel just simply set the upper thresh to max and lower thresh to min that will include the whole band of this channel.
Have fun, and hoping this will help.
Download this code
Download this code: File:CameraTune2.cpp
