mat

Is there a simple way to set all values in a cv::Mat to a given value if they fulfill some condition. For instance, I have CV_32FC1, and I want set all values which are 0 to 20. In MATLAB I would have simply done this: M(M == 0) = 20; You can use cv::Mat mask = M == 0; M.setTo(0.5, mask); However, it includes using additional memory for creating mask, but is a solution using opencv API therefore can be applied to all matrix types. If you consider performance issues, you can always refer directly to Mat::data to optimize this solution for concrete matrix type. This is a classic case for look-up

So I make a bitmap from a blob with the next code: byte[] blob = contact.getMP(); ByteArrayInputStream inputStream = new ByteArrayInputStream(blob); Bitmap bitmap = BitmapFactory.decodeStream(inputStream); Bitmap scalen = Bitmap.createScaledBitmap(bitmap, 320, 240, false); and it gives back the next output, which is good Then I do the following to make the bitmap into a Mat, but then my colors just change... //Mat ImageMat = new Mat(); Mat ImageMat = new Mat(320, 240, CvType.CV_32F); Utils.bitmapToMat(scalen, ImageMat); I have no idea why, nor another way to make the bitmap into a Mat. What is

I need to implement a function that receives a string containing the bytes of an image (received via boost socket connection) and converts the info into an OpenCV cv::Mat . I also know the width and height of the image and its size in bytes. My function looks like this: void createImageFromBytes(const std::string& name, std::pair<int,int> dimensions, const std::string& data) { int width,height; width = dimensions.first; height = dimensions.second; //convert data to cv::Mat image std::string filepng = DATA_PATH"/" + name +".png"; imwrite(filepng, image); } Which is the best method for doing

This maybe rudimentary, but is it possible to know how many channels a cv::Mat has? For eg, we load an RGB image, I know there are 3 channels. I do the following operations, just to get the laplacian of the image, which is straight from the Opencv Documentation. int main(int argc, char **argv) { Mat src = imread(argv[1],1),src_gray,dst_gray,abs_dst_gray; cvtColor(src,src_gray,COLOR_BGR2GRAY); GaussianBlur( src, src, Size(3,3), 0, 0, BORDER_DEFAULT ); Laplacian(src_gray,dst_gray,ddepth,kernel_size,scale,delta,BORDER_DEFAULT); convertScaleAbs(dst_gray,abs_dst_gray); } After converting to

i am using opencv in android. but when i am adding Mat() in my code my application unexpectedly stops after launch. my error log is as below: FATAL EXCEPTION: main java.lang.UnsatisfiedLinkError: n_Mat at org.opencv.core.Mat.n_Mat(Native Method) at org.opencv.core.Mat.<init>(Mat.java:441) at com.example.imagepro.MainActivity.onCreate(MainActivity.java:36) at android.app.Activity.performCreate(Activity.java:4465) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) at android.app

I'm trying to set a new color value to some pixel into a cv::Mat image my code is below: Mat image = img; for(int y=0;y<img.rows;y++) { for(int x=0;x<img.cols;x++) { Vec3b color = image.at<Vec3b>(Point(x,y)); if(color[0] > 150 && color[1] > 150 && color[2] > 150) { color[0] = 0; color[1] = 0; color[2] = 0; cout << "Pixel >200 :" << x << "," << y << endl; } else { color.val[0] = 255; color.val[1] = 255; color.val[2] = 255; } } imwrite("../images/imgopti"+to_string(i)+".tiff",image); It seems to get the good pixel in output (with cout) however in the output image (with imwrite) the pixel

I tried to display an image of CV_32F type using imshow function but it showed a WHITE image . In the Documentation its given that floating point images will be mapped to 0-255 and displayed but it just showed a white image.I tried to convert it to CV_8U using Mat A=Mat::ones(300,300,CV_32FC1)*1000; do some processing - assigning float values to pixels in A ...... Mat B; A.convertTo(B,CV_8U) When I imshow 'B' i get a black & white image, there are no shades of gray . Are the float valued pixels in A properly mapped to 0-255 ? Am I doing anything wrong? Few values in A are 1000 as initialized