The code below causes an exception. Why?
#include
#include
using namespace cv;
using namespace std;
void mai
How to fill Matrix with zeros in OpenCV?
To fill a pre-existing Mat
object with zeros, you can use Mat::zeros()
Mat m1 = ...;
m1 = Mat::zeros(1, 1, CV_64F);
To intialize a Mat
so that it contains only zeros, you can pass a scalar with value 0
to the constructor:
Mat m1 = Mat(1,1, CV_64F, 0.0);
// ^^^^double literal
The reason your version failed is that passing 0
as fourth argument matches the overload taking a void*
better than the one taking a scalar.
use cv::mat::setto
img.setTo(cv::Scalar(redVal,greenVal,blueVal))
If You are more into programming with templates, You may also do it this way...
template<typename _Tp>
... some algo ...
cv::Mat mat = cv::Mat_<_Tp>::zeros(rows, cols);
mat.at<_Tp>(i, j) = val;
You can choose filling zero data or create zero Mat.
Filling zero data with setTo():
img.setTo(Scalar::all(0));
Create zero data with zeros():
img = zeros(img.size(), img.type());
The img changes address of memory.
I presume you are talking about filling zeros of some existing mat? How about this? :)
mat *= 0;
You can use this to fill zeroes in a Mat object already containing data:
image1 = Scalar::all(0);
For eg, if you use it this way:
Mat image,image1;
image = imread("IMG_20160107_185956.jpg", CV_LOAD_IMAGE_COLOR); // Read the file
if(! image.data ) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
return -1;
}
cvtColor(image,image1,CV_BGR2GRAY);
image1 = Scalar::all(0);
It will work fine. But you cannot use this for uninitialised Mat. For that you can go for other options mentioned in above answers, like
Mat drawing = Mat::zeros( image.size(), CV_8UC3 );