I try to use a different way for stitching images, but I got the following error...I try to change the format of the images or the size but nothing happens...any ideas?
error:
Error: Assertion failed (imgs.size() == imgs_.size())
in unknown function, file ......\src\opencv\modules\stitching\src\stitcher.cpp
, line 128
my code:
int main( int argc, char** argv )
{
Stitcher stitcher = Stitcher::createDefault();
Mat image11,image22;
Mat pano,output_frame;
vector<Mat> imgs,currentFrames;
// Load the images
Mat image1= imread( argv[1] );
Mat image2= imread( argv[2] );
printf("-- umwandlung works");
currentFrames.push_back(image1);
currentFrames.push_back(image2);
stitcher.estimateTransform( currentFrames );
stitcher.composePanorama(currentFrames, output_frame );
waitKey(0);
}
This is because estimateTransform() is not able to stitch all the images you have provided. You can check how many images were stitched using Stitcher::component(), it returns a vector of ints, which size is your goal.
Therefore, in your case its size should be 2 if the stitching was successful.
The question is similiar to this one:
using compose panorama without estimateTransform
I've just answered you there.
Related
I'm new in opencv and I had this problem...
Given the following Mat type (globally declarated)
Mat src_gray;
Mat dst;
I have dst being a zero grayscale Mat with this initialization
dst=Mat::zeros(src_gray.size(), CV_BGR2GRAY);
It seems I can't edit the pixels on the dst image (when I use imwrite, it gives me a black image as if I hadn't done anything).
This is the code I currently have:
for(int i=0;i<=dst.cols;i++)
for(int j=0;j<=dst.rows;j++)
{
dst.at<uchar>(j,i)=255;
}
imwrite( "img_res.png", dst );
The result Image has the dimensions it's supposed to have, but it is a black pixeled picture, shouldn't it be a white pixeled Image?
I don't know if it is relevant if I mention that I have 3 global Mats
Mat image;
Mat src_gray;
Mat dst;
Which are initialized this way:
image = imread( argv[1], 1 );
cvtColor( image, src_gray, CV_BGR2GRAY );
Then, I release them as:
image.release();
dst.release();
src_gray.release();
The other problem I get is that when I release the Mats (during execution), I get the "Segmentation fault (core dumped)" error. (I code from Linux Ubuntu distri)
Try:
dst=Mat::zeros(src_gray.size(), CV_8UC1);
When you use CV_BGR2GRAY, you are creating a Mat with 3 color channels, then, it's not possible to assign a number when you have an array of numbers (B,G,R).
With CV_8UC1, you create a Mat with 1 color channel of uchar then it should works with:
dst.at<uchar>(j,i)=255;
I need to extract L(illuminative component)from RGB frame and obtain the inverted illuminative image (L).
adding the inverted image to the original L image.
My question is how can i add two images (L channel of lab and inverted image)?
Which function can do that?
i think http://answers.opencv.org/question/81947 is your question. so i tried to revise it as far as i understand your question. hope it will help.
source :
result :
#include "opencv2/opencv.hpp"
using namespace cv;
using namespace std;
void split_lab( Mat planes )
{
Mat lab, blurredL;
cvtColor( planes, lab, CV_BGR2Lab );
vector <Mat> splits;
split(lab, splits);
medianBlur( splits[0], blurredL, 31);
blurredL = 255 - blurredL;
cvtColor( blurredL, blurredL, CV_GRAY2BGR );
planes = planes + ( blurredL * 0.5 );
}
int main(int argc, char** argv)
{
Mat src= imread( argv[1] );
split_lab(src);
imshow( "result", src );
waitKey();
return 0;
}
Does someone know of the link to BRIEF implementation with OpenCV 2.4? Regards.
PS: I know such questions are generally not welcome on SO, as the primary focus is what work you have done. But there was a similar question which was quite well received.
One of the answers to that questions suggests a generic manner for SIFT, which could be extended to BRIEF. Here is my slightly modified code.
#include <opencv2/nonfree/nonfree.hpp>
#include <opencv2/highgui/highgui.hpp>
//using namespace std;
using namespace cv;
int main(int argc, char *argv[])
{
Mat image = imread("load02.jpg", CV_LOAD_IMAGE_GRAYSCALE);
cv::initModule_nonfree();
// Create smart pointer for SIFT feature detector.
Ptr<FeatureDetector> featureDetector = FeatureDetector::create("HARRIS"); // "BRIEF was initially written. Changed after answer."
vector<KeyPoint> keypoints;
// Detect the keypoints
featureDetector->detect(image, keypoints); // NOTE: featureDetector is a pointer hence the '->'.
//Similarly, we create a smart pointer to the SIFT extractor.
Ptr<DescriptorExtractor> featureExtractor = DescriptorExtractor::create("BRIEF");
// Compute the 128 dimension SIFT descriptor at each keypoint.
// Each row in "descriptors" correspond to the SIFT descriptor for each keypoint
Mat descriptors;
featureExtractor->compute(image, keypoints, descriptors);
// If you would like to draw the detected keypoint just to check
Mat outputImage;
Scalar keypointColor = Scalar(255, 0, 0); // Blue keypoints.
drawKeypoints(image, keypoints, outputImage, keypointColor, DrawMatchesFlags::DEFAULT);
namedWindow("Output");
imshow("Output", outputImage);
char c = ' ';
while ((c = waitKey(0)) != 'q'); // Keep window there until user presses 'q' to quit.
return 0;
}
The issue with this code is that it gives an error: First-chance exception at 0x00007FFB84698B9C in Project2.exe: Microsoft C++ exception: cv::Exception at memory location 0x00000071F4FBF8E0.
The error results in the function execution breaking. A tag says that execution will resume at the namedWindow("Output"); line.
Could someone please help fix this issue, or suggest a new code altogether? Thanks.
EDIT: The terminal now shows an error: Assertion failed (!outImage.empty()) in cv::drawKeypoints, file ..\..\..\..opencv\modules\features2d\src\draw.cpp, line 115. The next statement from where the code will resume remains the same, as drawKepoints is called just before it.
In OpenCV, BRIEF is a DescriptorExtractor, not a FeatureDetector. According to FeatureDetector::create, this factory method does not support "BRIEF" algorithm. In other words, FeatureDetector::create("BRIEF") returns a null pointer and your program crashes.
The general steps in feature matching are:
Find some interesting (feature) points in an image: FeatureDetector
Find a way to describe those points: DescriptorExtractor
Try to match descriptors (feature vectors) in two images: DescriptorMatcher
BRIEF is an algorithm only for step 2. You can use some other methods, HARRIS, ORB, ..., in step 1 and pass the result to step 2 using BRIEF. Besides, SIFT can be used in both step 1 and 2 because the algorithm provides methods for both steps.
Here's a simple example to use BRIEF in OpenCV. First step, find points that looks interesting (key points) in an image:
vector<KeyPoint> DetectKeyPoints(const Mat &image)
{
auto featureDetector = FeatureDetector::create("HARRIS");
vector<KeyPoint> keyPoints;
featureDetector->detect(image, keyPoints);
return keyPoints;
}
You can try any FeatureDetector algorithm instead of "HARRIS". Next step, compute the descriptors from key points:
Mat ComputeDescriptors(const Mat &image, vector<KeyPoint> &keyPoints)
{
auto featureExtractor = DescriptorExtractor::create("BRIEF");
Mat descriptors;
featureExtractor->compute(image, keyPoints, descriptors);
return descriptors;
}
You can use algorithm different than "BRIEF", too. And you can see that the algorithms in DescriptorExtractor is not the same as the algorithms in FeatureDetector. The last step, match two descriptors:
vector<DMatch> MatchTwoImage(const Mat &descriptor1, const Mat &descriptor2)
{
auto matcher = DescriptorMatcher::create("BruteForce");
vector<DMatch> matches;
matcher->match(descriptor1, descriptor2, matches);
return matches;
}
Similarly, you can try different matching algorithm other than "BruteForce". Finally back to main program, you can build the application from those functions:
auto img1 = cv::imread("image1.jpg");
auto img2 = cv::imread("image2.jpg");
auto keyPoints1 = DetectKeyPoints(img1);
auto keyPoints2 = DetectKeyPoints(img2);
auto descriptor1 = ComputeDescriptors(img1, keyPoints1);
auto descriptor2 = ComputeDescriptors(img2, keyPoints2);
auto matches = MatchTwoImage(descriptor1, descriptor2);
and use matches vector to complete your application. If you want to check the results, OpenCV also provides functions to draw results of step 1 & 3 in an image. For example, draw the matches in the final step:
Mat result;
drawMatches(img1, keyPoints1, img2, keyPoints2, matches, result);
imshow("result", result);
waitKey(0);
#include <opencv/cv.h>
#include <opencv/highgui.h>
using namespace cv;
int main( int argc, char** argv )
{
const char* imageName = "samp.png";
Mat image;
image = imread( imageName, 1 );
Mat gray_image;
cvtColor( image, gray_image, CV_BGR2GRAY );
imwrite( "/home/Downloads/Pictures/Gray_Image.jpg",gray_image );
namedWindow( imageName, CV_WINDOW_AUTOSIZE );
namedWindow( "Gray image", CV_WINDOW_AUTOSIZE );
imshow( imageName, image );
imshow( "Gray image", gray_image );
waitKey(0);
return 0;
}
'imwrite" in the above code does not create image.Everything else works fine,and I can see the image using imshow.But I dont know why it is not creating a image.I tried 'convertTo' and replacing '/' to '\' in the path, but it does not work.I will be pleased if I get any lead.Thanks!
This is not documented clearly, but imwrite returns a boolean which is true if and only if it thinks that it could write the file successfully. You should check that value!
You'll probably find out that imwrite returns false. Most likely you do not have sufficient permissions or -- as berak pointed out -- your file path is invalid.
By the way, for proper error handling, you should also catch exceptions, in particular, if the user provides the output file URL. If OpenCV, for some reason, can't find a suitable encoder (i.e. it can't recognize which type of file you are going to write), it will throw an exception.
Markus Mayr's response helped me find out that I was getting a false when I printed the result of imwrite. The reason turned out to be, the directory in which I was trying to write, didnt exist. I was assuming it will create the directory but imwrite silently failed.After I manually created the directory it worked
I am trying to learn some basics, but I keep getting errors.
I am trying to resize a cv::Mat
Edit to clarify why I am not loading an image: I am trying to test without having access to external files.
Inside the code, though, I put int x = M.depth(); and it read 0
cv::Mat M(2,2, CV_8UC3, cv::Scalar(0,0,255));
scale = 2;
cv::Size myImageSize;
myImageSize.height = M.rows;
myImageSize.width = M.cols;
cv::Mat ImgCopy = cvCreateImage(myImageSize, M.depth(), M.channels());
..
cv::resize(M, ImgCopy, myImageSize, 0, 0, CV_INTER_LINEAR);
I am getting an error on the line cvCreateImage
Input image depth is not supported by function (Unsupported format) in unknown functio, file... \modules\core\src\array.cpp...
I have tried with other values (CV_32F...) and I get the same error.
Please help !
cvCreateImage() is for use with the C API and returns an IplImage*. To initialize a cv::Mat, use the appropriate constructor.
cv::Mat ImgCopy(M.size(), M.type());
is the most succinct way to create and allocate memory for a new cv::Mat.
However, cv::resize() makes it even easier. You just have to declare your image
cv::Mat ImgCopy
and the arguments to cv::resize() allow automatic calculation of the correct dimensions and type. The last three parameters do not need to be specified because you don't change them from the defaults.
cv::resize(M, ImgCopy, myImageSize);
Try this code :
using namespace cv;
using namespace std;
int main( int argc, char** argv )
{
IplImage *src,*dst;
src=cvLoadImage("img.png");
cvNamedWindow("SRC", CV_WINDOW_AUTOSIZE);
cvNamedWindow("DST", CV_WINDOW_AUTOSIZE);
dst = cvCreateImage(cvSize(500,500),src->depth,src->nChannels);
cvResize(src,dst);
cvShowImage("SRC",src);
cvShowImage("DST",dst);
cvWaitKey(0);
cvDestroyWindow("SRC");
cvDestroyWindow("DST");
cvReleaseImage(&dst);
cvReleaseImage(&src);
return 0;
}