I apply watershed segmentation to detect touching objects and it works okay doing that. Now, I would like to draw contours of each object, so I can get their length, area, moments etc.. But the objects in the result of the segmentation are still touching. So, I fail to draw contours of each one. How can I draw contours of each object?
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
using namespace std;
using namespace cv;
int main()
{
Mat src = imread("source.png");
// Create binary image from source image
Mat srcGray;
cvtColor(src, srcGray, CV_BGR2GRAY);
Mat srcThresh;
threshold(srcGray, srcThresh, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);
// Perform the distance transform algorithm
Mat dist;
distanceTransform(srcThresh, dist, CV_DIST_L2, 3);
// Normalize the distance image for range = {0.0, 1.0}
normalize(dist, dist, 0, 1., NORM_MINMAX);
// Threshold to obtain the peaks
threshold(dist, dist, 0.1, 3.5, CV_THRESH_BINARY);
// Create the CV_8U version of the distance image
Mat dist_8u;
dist.convertTo(dist_8u, CV_8U);
// Find total markers
std::vector<std::vector<Point> > contours;
findContours(dist_8u, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
int ncomp = contours.size();
// Create the marker image for the watershed algorithm
Mat markers = Mat::zeros(dist.size(), CV_32SC1);
// Draw the foreground markers
for (int i = 0; i < ncomp; i++)
drawContours(markers, contours, i, Scalar::all(i + 1), -1);
// Draw the background marker
circle(markers, Point(5, 5), 3, CV_RGB(255, 255, 255), -1);
// Perform the watershed algorithm
watershed(src, markers);
Mat wgResult = (markers.clone()) * 10000;
imshow("Watershed", wgResult);
waitKey(0);
return 0;
}
Source image:
Watershed Result:
The markers matrix returned by watershed contains the indices of the segmented regions, according to the seed. So each component will have the same seed value. You can then create a binary matrix for each seed like:
Mat1b mask = (markers == seed);
Once you have the binary mask for each component, you can easily compute its area, moments, etc...
Code:
#include <opencv2/opencv.hpp>
#include <iostream>
using namespace std;
using namespace cv;
int main()
{
Mat src = imread("D:\\SO\\img\\postit.png");
// Create binary image from source image
Mat srcGray;
cvtColor(src, srcGray, CV_BGR2GRAY);
Mat srcThresh;
threshold(srcGray, srcThresh, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);
// Perform the distance transform algorithm
Mat dist;
distanceTransform(srcThresh, dist, CV_DIST_L2, 3);
// Normalize the distance image for range = {0.0, 1.0}
normalize(dist, dist, 0, 1., NORM_MINMAX);
// Threshold to obtain the peaks
threshold(dist, dist, 0.1, 3.5, CV_THRESH_BINARY);
// Create the CV_8U version of the distance image
Mat dist_8u;
dist.convertTo(dist_8u, CV_8U);
// Find total markers
std::vector<std::vector<Point> > contours;
findContours(dist_8u, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
int ncomp = contours.size();
// Create the marker image for the watershed algorithm
Mat markers = Mat::zeros(dist.size(), CV_32SC1);
// Draw the foreground markers
for (int i = 0; i < ncomp; i++)
drawContours(markers, contours, i, Scalar::all(i + 1), -1);
// Draw the background marker
circle(markers, Point(5, 5), 3, CV_RGB(255, 255, 255), -1);
// Perform the watershed algorithm
watershed(src, markers);
for (int seed = 1; seed <= ncomp; ++seed)
{
Mat1b mask = (markers == seed);
// Now you have the mask, you can compute your statistics
imshow("Mask", mask);
waitKey();
}
return 0;
}
There are many way to do this. Depending on the current image that have been shown, you can simply do erosion and dilation operation on order to separate them. However this will not work if the elapse area is bigger.
You need a closing operation:
http://docs.opencv.org/2.4/doc/tutorials/imgproc/opening_closing_hats/opening_closing_hats.html
threshold it.
apply closing operation.
get contours
Related
I am detecting red triangle objects in real time video using OpenCv c++. But my program is not working properly. Whether I cannot use findContours or approxPolyDP not much well. Here is my code
#include "opencv2/opencv.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
#include <raspicam/raspicam_cv.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
using namespace std;
int thresh = 100;
int number_pixels;
void drawAllTriangles(Mat&, const vector< vector<Point> >&);
int main(){
//Vectors
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
Mat canny_output,drawing;
//Initialise the image as a matrix container
Mat bgr;
raspicam::RaspiCam_Cv capture; // initialise the raspicam object
capture.open(); // activate the raspicam object
while (1)
{
capture.grab(); //grab the scene using raspicam
capture.retrieve(bgr); // retrieve the captured scene as an image and store it in matrix container
Mat gray,hsv; //Initialise the matrix container for gray color image
resize(bgr, bgr, Size(), .25, 0.25, CV_INTER_AREA);
//cvtColor(bgr, gray, COLOR_BGR2GRAY); //OpenCV code line for converting COLOR to GRAY scale image
//
cvtColor(bgr, hsv, COLOR_BGR2HSV);
//Gaussian Noice
Mat blure;
GaussianBlur(hsv,blure,Size(9,9),1.0);
//Gaussian Noice End
Mat mask1, mask2;
inRange(blure, Scalar(0,70,50), Scalar(10, 255, 255), mask1);
inRange(blure, Scalar(170, 70, 50), Scalar(180, 255, 255), mask2);
Mat mask3 = mask1 | mask2;
//Mat mask3 = mask1;
//
number_pixels = countNonZero(mask3);
Canny(mask3, canny_output, thresh, thresh*2, 3 );
findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
imshow("Original frame", bgr); //displaying original frame
imshow("Gray frame", mask3); //displaying original frame
drawAllTriangles(drawing,contours);
imshow("Triangles",drawing);
if (cvWaitKey(20) == 'q') // waitkey
break;
}
capture.release(); // release the raspicam frame grabbing
return 0;
}
void drawAllTriangles(Mat& img, const vector< vector<Point> >& contours){
vector<Point> approxTriangle;
for(size_t i = 0; i < contours.size(); i++){
approxPolyDP(contours[i], approxTriangle, arcLength(Mat(contours[i]), true)*0.05, true);
if(approxTriangle.size() == 3 and number_pixels>200){
drawContours(img, contours, i, Scalar(0, 255, 255), CV_FILLED); // fill GREEN
vector<Point>::iterator vertex;
for(vertex = approxTriangle.begin(); vertex != approxTriangle.end(); ++vertex){
circle(img, *vertex, 3, Scalar(0, 0, 255), 1);
}
printf("Triangle \n");
}
else {
printf("None \n");
}
}
}
My program should detect any red triangle shaped objects in video. Where I am going wrong. Thank you for answer
THese are the images, but it cannot detect triangles and confusing.
Im trying to detect the pallet in forklift. but find contours cant detect the rectangle in a correct way.
how can I detect the large pallet.
I have tried hough transform but it fails of detecting the forklift rectangle, so I'm using findcontours instead.
pallet
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
int main()
{
cv::Mat input = cv::imread("pallet.jpg");
// convert to grayscale (you could load as grayscale instead)
cv::Mat gray;
cv::cvtColor(input,gray, CV_BGR2GRAY);
// compute mask (you could use a simple threshold if the image is always as good as the one you provided)
cv::Mat mask;
cv::threshold(gray, mask, 0, 255, CV_THRESH_BINARY_INV | CV_THRESH_OTSU);
// find contours (if always so easy to segment as your image, you could just add the black/rect pixels to a vector)
std::vector<std::vector<cv::Point> > contours;
std::vector<cv::Vec4i> hierarchy;
cv::findContours(mask,contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
/// Draw contours and find biggest contour (if there are other contours in the image, we assume the biggest one is the desired rect)
// drawing here is only for demonstration!
int biggestContourIdx = -1;
float biggestContourArea = 0;
cv::Mat drawing = cv::Mat::zeros( mask.size(), CV_8UC3 );
for( int i = 0; i< contours.size(); i++ )
{
cv::Scalar color = cv::Scalar(0, 100, 0);
drawContours( drawing, contours, i, color, 1, 8, hierarchy, 0, cv::Point() );
float ctArea= cv::contourArea(contours[i]);
if(ctArea > biggestContourArea)
{
biggestContourArea = ctArea;
biggestContourIdx = i;
}
}
// if no contour found
if(biggestContourIdx < 0)
{
std::cout << "no contour found" << std::endl;
return 1;
}
// compute the rotated bounding rect of the biggest contour! (this is the part that does what you want/need)
cv::RotatedRect boundingBox = cv::minAreaRect(contours[biggestContourIdx]);
// one thing to remark: this will compute the OUTER boundary box, so maybe you have to erode/dilate if you want something between the ragged lines
// draw the rotated rect
cv::Point2f corners[4];
boundingBox.points(corners);
cv::line(drawing, corners[0], corners[1], cv::Scalar(255,255,255));
cv::line(drawing, corners[1], corners[2], cv::Scalar(255,255,255));
cv::line(drawing, corners[2], corners[3], cv::Scalar(255,255,255));
cv::line(drawing, corners[3], corners[0], cv::Scalar(255,255,255));
// display
cv::imshow("input", input);
cv::imshow("drawing", drawing);
cv::waitKey(0);
cv::imwrite("rotatedRect.png",drawing);
return 0;
}
I am new to OpenCV and I am using this code to bound the text area in image. After that I am filtering contours and putting the bounded rectangle to a vector<Rect> to copy these to new image.
Mat large = img1;
Mat rgb;
// downsample and use it for processing
pyrUp(large, rgb);
Mat small;
cvtColor(rgb, small, CV_BGR2GRAY);
// morphological gradient
Mat grad;
Mat morphKernel = getStructuringElement(MORPH_ELLIPSE, Size(2, 2));
morphologyEx(small, grad, MORPH_GRADIENT, morphKernel);
// binarize
Mat bw;
threshold(grad, bw, 0.0, 255.0, THRESH_BINARY | THRESH_OTSU);
// connect horizontally oriented regions
Mat connected;
//morphKernel = getStructuringElement(MORPH_RECT, Size(7, 1));
//morphologyEx(bw, connected, MORPH_CLOSE, morphKernel);
// find contours
connected = bw;
Mat mask = Mat::zeros(bw.size(), CV_8UC1);
Mat mask2;
Mat mask3;
vector<vector<Point>> contours;
vector<Vec4i> hierarchy;
findContours(connected, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
/*drawContours(mask2, contours, -1, Scalar(255), CV_FILLED);
Mat Crop(img1.rows, img1.cols, CV_8UC3);
Crop.setTo(Scalar(0, 255, 0));
img1.copyTo(Crop, mask2);
normalize(mask2.clone(), mask2, 0.0, 255.0, CV_MINMAX, CV_8UC1);
*/
vector<Rect> rect1;
int i = 0;
//filter contours
for (int idx = 0; idx >= 0; idx = hierarchy[idx][0])
{
Rect rect = boundingRect(contours[idx]);
Mat maskROI(mask, rect);
maskROI = Scalar(0, 0, 0);
// fill the contour
drawContours(mask, contours, idx, Scalar(255, 255, 255), CV_FILLED);
// ratio of non-zero pixels in the filled region
double r = (double)countNonZero(maskROI) / (rect.width*rect.height);
if (r > .45 /* assume at least 45% of the area is filled if it contains text */
&&
(rect.height > 10 && rect.width > 10 && rect.height<150 && rect.width<150) /* constraints on region size */
/* these two conditions alone are not very robust. better to use something
like the number of significant peaks in a horizontal projection as a third condition */
)
{
//making rectangles on bounded area
rectangle(rgb, rect, Scalar(0, 255, 0), 2);
//pushing bounding rectangles in vector for new mask
rect1.push_back(rect);
}
}
Input output I am getting after bounded text ares is:
After that I am using this code to copy the bounded area only to new mask
//copying bounded rectangles area from small to new mask2
for (int i = 0; i < rect1.size(); i++){
mask2 = rgb(rect1[i]);
}
but by using this I only get this last bounded text area:
How can I get or update the mask2 rows or cols to get all the mapping of bounded text areas from rgb to mask2.
That's because mask2 will be equal to the last rgb(rect1[i]) called.
You can easily solve this in two ways (using copyTo):
Create a mask (black initialized, same size as input image), where you draw (white) rectangles. Then you copy the original image to a black initialized image of the same size, using the obtained mask.
Copy each sub-image directly to a black initialized image.
Starting from this image, where the red rectangles will be your detected rectangles:
With first approach you'll get a mask like:
and, for both approaches, the final result will be:
Code for first approach:
#include <opencv2/opencv.hpp>
#include <vector>
using namespace std;
using namespace cv;
int main()
{
// Your image
Mat3b img = imread("path_to_image");
// Your rectangles
vector<Rect> rects{Rect(100, 100, 100, 200), Rect(300, 200, 200, 100), Rect(500, 400, 80, 130)};
// Mask for rectangles (black initializeds)
Mat1b mask(img.rows, img.cols, uchar(0));
Mat3b dbgRects = img.clone();
for (int i = 0; i < rects.size(); ++i)
{
// Draw white rectangles on mask
rectangle(mask, rects[i], Scalar(255), CV_FILLED);
// Show rectangles
rectangle(dbgRects, rects[i], Scalar(0, 0, 255), 2);
}
// Black initizlied result
Mat3b result(img.rows, img.cols, Vec3b(0,0,0));
img.copyTo(result, mask);
imshow("Rectangles", dbgRects);
imshow("Result", result);
waitKey();
return 0;
}
Code for second approach:
#include <opencv2/opencv.hpp>
#include <vector>
using namespace std;
using namespace cv;
int main()
{
// Your image
Mat3b img = imread("path_to_image");
// Your rectangles
vector<Rect> rects{Rect(100, 100, 100, 200), Rect(300, 200, 200, 100), Rect(500, 400, 80, 130)};
// Black initizlied result
Mat3b result(img.rows, img.cols, Vec3b(0, 0, 0));
Mat3b dbgRects = img.clone();
for (int i = 0; i < rects.size(); ++i)
{
img(rects[i]).copyTo(result(rects[i]));
// Show rectangles
rectangle(dbgRects, rects[i], Scalar(0, 0, 255), 2);
}
imshow("Rectangles", dbgRects);
imshow("Result", result);
waitKey();
return 0;
}
My code is the same as this tutorial.
When I see the result image after using cv::watershed(), there is a object(upper-right) that I want to find out, but it's missing.
There are indeed six marks in image after using cv::drawContours().
Is this normal because the inaccuracy of the watershed algorithm exist?
Here is part of my code:
Mat src = imread("result01.png");
Mat gray;
cvtColor(src, gray, COLOR_BGR2GRAY);
Mat thresh;
threshold(gray, thresh, 0, 255, THRESH_BINARY | THRESH_OTSU);
// noise removal
Mat kernel = Mat::ones(3, 3, CV_8UC1);
Mat opening;
morphologyEx(thresh, opening, MORPH_OPEN, kernel, Point(-1, -1), 2);
// Perform the distance transform algorithm
Mat dist_transform;
distanceTransform(opening, dist_transform, CV_DIST_L2, 5);
// Normalize the distance image for range = {0.0, 1.0}
// so we can visualize and threshold it
normalize(dist_transform, dist_transform, 0, 1., NORM_MINMAX);
// Threshold to obtain the peaks
// This will be the markers for the foreground objects
Mat dist_thresh;
threshold(dist_transform, dist_thresh, 0.5, 1., CV_THRESH_BINARY);
Mat dist_8u;
dist_thresh.convertTo(dist_8u, CV_8U);
// Find total markers
vector<vector<Point> > contours;
findContours(dist_8u, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
// Create the marker image for the watershed algorithm
Mat markers = Mat::zeros(dist_thresh.size(), CV_32SC1);
// Draw the foreground markers
for (size_t i = 0; i < contours.size(); i++)
drawContours(markers, contours, static_cast<int>(i), Scalar::all(static_cast<int>(i)+1), -1);
// Perform the watershed algorithm
watershed(src, markers);
Original image:
Result after watershed:
You can find original, intermediate and result image here:
Result images after specific process
In your example, what you consider background is given the same label (5) as the "missing" object.
You can easily adjust this by setting a label (>0) to background, too.
You can find what is for sure background dilating and negating the thresh image.
Then, when creating a marker, you define the labels as:
0: unknown
1: background
>1 : your objects
In your output image, markers will have:
-1 : the edges between objects
0: the background (as intended by watershed)
1: the background (as you defined)
>1 : your objects.
This code should help:
#include <opencv2\opencv.hpp>
#include <vector>
using namespace std;
using namespace cv;
int main()
{
Mat3b src = imread("path_to_image");
Mat1b gray;
cvtColor(src, gray, COLOR_BGR2GRAY);
Mat1b thresh;
threshold(gray, thresh, 0, 255, THRESH_BINARY | THRESH_OTSU);
// noise removal
Mat1b kernel = getStructuringElement(MORPH_RECT, Size(3,3));
Mat1b opening;
morphologyEx(thresh, opening, MORPH_OPEN, kernel, Point(-1, -1), 2);
Mat1b kernelb = getStructuringElement(MORPH_RECT, Size(21, 21));
Mat1b background;
morphologyEx(thresh, background, MORPH_DILATE, kernelb);
background = ~background;
// Perform the distance transform algorithm
Mat1f dist_transform;
distanceTransform(opening, dist_transform, CV_DIST_L2, 5);
// Normalize the distance image for range = {0.0, 1.0}
// so we can visualize and threshold it
normalize(dist_transform, dist_transform, 0, 1., NORM_MINMAX);
// Threshold to obtain the peaks
// This will be the markers for the foreground objects
Mat1f dist_thresh;
threshold(dist_transform, dist_thresh, 0.5, 1., CV_THRESH_BINARY);
Mat1b dist_8u;
dist_thresh.convertTo(dist_8u, CV_8U);
// Find total markers
vector<vector<Point> > contours;
findContours(dist_8u, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
// Create the marker image for the watershed algorithm
Mat1i markers(dist_thresh.rows, dist_thresh.cols, int(0));
// Background as 1
Mat1i one(markers.rows, markers.cols, int(1));
bitwise_or(one, markers, markers, background);
// Draw the foreground markers (from 2 up)
for (int i = 0; i < int(contours.size()); i++)
drawContours(markers, contours, i, Scalar(i+2), -1);
// Perform the watershed algorithm
Mat3b dbg;
cvtColor(opening, dbg, COLOR_GRAY2BGR);
watershed(dbg, markers);
Mat res;
markers.convertTo(res, CV_8U);
normalize(res, res, 0, 255, NORM_MINMAX);
return 0;
}
Result:
there is very little emgu cv data on watershed.
here is my translation to this problem using c#. i know it is not the right forum but this answer kips popping up so to all the searchers:
//Mat3b src = imread("path_to_image");
//cvtColor(src, gray, COLOR_BGR2GRAY);
Image<Gray, byte> gray = smallImage.Convert<Gray, byte>();
//threshold(gray, thresh, 0, 255, THRESH_BINARY | THRESH_OTSU);
Image<Gray, byte> thresh = gray.ThresholdBinaryInv(new Gray(55), new Gray(255));
// noise removal
Mat kernel = CvInvoke.GetStructuringElement(ElementShape.Rectangle, new Size(3, 3), new Point(-1, -1));
//Mat1b opening;
//morphologyEx(thresh, opening, MORPH_OPEN, kernel, Point(-1, -1), 2);
Image<Gray, byte> opening = thresh.MorphologyEx(MorphOp.Open, kernel, new Point(-1, -1), 2, BorderType.Default, new MCvScalar(255));
//Mat1b kernelb = getStructuringElement(MORPH_RECT, Size(21, 21));
Mat kernel1 = CvInvoke.GetStructuringElement(ElementShape.Rectangle, new Size(3, 3), new Point(-1, -1));
//Mat1b background;
//morphologyEx(thresh, background, MORPH_DILATE, kernelb);
Image<Gray, byte> background = thresh.MorphologyEx(MorphOp.Dilate, kernel, new Point(-1, -1), 2, BorderType.Default, new MCvScalar(255));
background = ~background;
//// Perform the distance transform algorithm
//Mat1f dist_transform;
//distanceTransform(opening, dist_transform, CV_DIST_L2, 5);
Image<Gray, float> dist_transform = new Image<Gray, float>(opening.Width, opening.Height);
CvInvoke.DistanceTransform(opening, dist_transform, null, DistType.L2, 5);
//// Normalize the distance image for range = {0.0, 1.0}
//// so we can visualize and threshold it
//normalize(dist_transform, dist_transform, 0, 1., NORM_MINMAX);
CvInvoke.Normalize(dist_transform, dist_transform, 0, 1.0, NormType.MinMax, DepthType.Default);
//// Threshold to obtain the peaks
//// This will be the markers for the foreground objects
//Mat1f dist_thresh;
//threshold(dist_transform, dist_thresh, 0.5, 1., CV_THRESH_BINARY);
Image<Gray, float> dist_thresh = new Image<Gray, float>(opening.Width, opening.Height);
CvInvoke.Threshold(dist_transform, dist_thresh, 0.5, 1.0, ThresholdType.Binary);
//Mat1b dist_8u;
//dist_thresh.convertTo(dist_8u, CV_8U);
Image<Gray, Byte> dist_8u = dist_thresh.Convert<Gray, Byte>();
//// Find total markers
//vector<vector<Point>> contours;
//findContours(dist_8u, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint();
CvInvoke.FindContours(dist_8u, contours, null, RetrType.External, ChainApproxMethod.ChainApproxSimple);
//// Create the marker image for the watershed algorithm
//Mat1i markers(dist_thresh.rows, dist_thresh.cols, int(0));
Image<Gray, int> markers = new Image<Gray, int>(dist_thresh.Width, dist_thresh.Height, new Gray(0));
//// Background as 1
//Mat1i one(markers.rows, markers.cols, int(1));
//bitwise_or(one, markers, markers, background);
Image<Gray, int> one = new Image<Gray, int>(markers.Cols, markers.Rows, new Gray(1));
CvInvoke.BitwiseOr(one, markers, markers, background);
//// Draw the foreground markers (from 2 up)
for (int i = 0; i < contours.Size; i++)
// drawContours(markers, contours, i, Scalar(i + 2), -1);
CvInvoke.DrawContours(markers, contours, i, new MCvScalar(i + 2));
//// Perform the watershed algorithm
//Mat3b dbg;
//cvtColor(opening, dbg, COLOR_GRAY2BGR);
//watershed(dbg, markers);
Image<Bgr, byte> dbg = new Image<Bgr, byte>(markers.Cols, markers.Rows);
CvInvoke.CvtColor(opening, dbg, ColorConversion.Gray2Bgr);
CvInvoke.Watershed(dbg, markers);
//Mat res;
//markers.convertTo(res, CV_8U);
//normalize(res, res, 0, 255, NORM_MINMAX);
CvInvoke.Normalize(markers, markers, 0, 255, NormType.MinMax);
//return 0;
to find light objects on dark background replace ThresholdBinaryInv with ThresholdBinary
So I've been working on recognizing a yoga ball with Hough Circles. Now, when converted to grayscale, it works straight away. Unfortunately, I have to take a more complicated procedure due to there being multiple of these coloured balls and only wanted to detect the blue.
Unfiltered ball:
Filtered ball:
Steps of my algorithm:
convert from BGR to HSV
blur the image
filter HSV for only select values (in my case dark blue to light blue due to lighting)
invert the image
use morphology to fill in the part that was lighted
blur again
filter the blur so it's a solid shape instead of unrecognisable blurry grayscale
detect with hough-circles. The MAT is still Grayscale so that isn't the problem.
Code:
#include <iostream>
#include <string>
#include <iomanip>
#include <sstream>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace std;
using namespace cv;
int main(int argc, char *argv[])
{
// Morphology stuff
Mat element5(30, 30, CV_8U, Scalar(1));
int morph_elem = 1; // 2
int morph_size = 33;// 30
int morph_operator = 2; // 2
Mat element = getStructuringElement(morph_elem, Size(2 * morph_size + 1, 2 * morph_size + 1), Point(morph_size, morph_size));
int const max_operator = 4;
int const max_elem = 2;
int const max_kernel_size = 21;
Mat kernel;
// Display Windows Name
namedWindow("Testing Purposes", CV_WINDOW_AUTOSIZE);
Mat src; // loaded image
Mat hsv; // changed src into HSV
Mat Filtered; // filtered w/ inRange for blue ball
Mat Gray; // gray filter for src
Mat dst; // destination for canny edge
Mat detected_edges; // matrix of edges w/ canny
// thresholds for canny
int edgeThresh = 45;
int lowThreshold;
int const max_lowThreshold = 100;
src = imread(argv[1]);
cvtColor(src, Gray, CV_BGR2GRAY);
cvtColor(src, hsv, CV_BGR2HSV);
/*
// CannyEdge Testing
blur(Gray, detected_edges, Size(3, 3)); // blur the grayimage
Canny(detected_edges, detected_edges, lowThreshold, lowThreshold * ratio, kernel_size);
dst = Scalar::all(0);
src.copyTo( dst, detected_edges);
imshow(window_name,dst);
*/
// hsv blur and then thresholds
blur(hsv,hsv,Size(4, 4), Point(-1, -1));
inRange(hsv, Scalar(100, 100, 0), Scalar(200, 200, 255), Filtered); //filtering after blur
vector<Vec3f> circles; //vector for holding info on circles
// houghcircles - attempts to detect circles in the Filtered image we passed it
// morphology defintion for Kernel
bitwise_not(Filtered, Filtered);
// imwrite("/home/bjacobs/Desktop/Testing.jpg", Filtered);
imwrite("/home/bjacobs/Desktop/Testingg.jpg", Filtered);
morphologyEx(Filtered, dst, MORPH_OPEN, element);
blur(dst, dst, Size(20, 20), Point(-1, -1));
Mat baw = dst > 128;
HoughCircles(baw ,circles, CV_HOUGH_GRADIENT, 1, baw.rows/8,200,100,0,0);
imwrite("/home/bjacobs/Desktop/Testing.jpg", baw);
// Draw the circles detected onto the SRC file
for(size_t i = 0; i < circles.size(); i++)
{
Point center(cvRound(circles[i][0]), cvRound(circles[i][3]));
int radius = cvRound(circles[i][2]);
// circle center
circle(src, center, 3, Scalar(0, 255, 0), -1, 8, 0);
// circle outline
circle(src, center, radius, Scalar(0, 0, 255), 3, 8, 0);
}
imwrite("/home/bjacobs/Desktop/Test.jpg", hsv);
imshow("Testing Purposes", src);
waitKey(0);
}
I've already read as much as I possibly could online on this matter, and nothing I've found so far has helped. Forgive the sloppy commenting, and there are some failed algorithms included with using Canny Edge detection, so don't pay too much mind to them. Does anyone know of a solution to this detection issue?
Instead of using houghcircle you can do the following.
Segment the blue color.
Find contours(largest).
Minimum enclosing circle for contour.