OpenCV copyTo() mask error

1
votes

I'm trying to paste a smaller image into a larger image, using masks in OpenCV 2.4 via C++.
Without a mask, I copy the small image to the larger image with the following code:

smallImage.copyTo(largeImage(cv::Rect(pt, smallImage.size()));

where pt has the type of cv::Point2f. It works perfectly. However, if I apply a mask:

smallImage.copyTo(largeImage(cv::Rect(pt, smallImage.size()), mask);

I get an error from Mat::create (see documentation): 

CV_Assert(!fixedType() || (CV_MAT_CN(type) ==
    m.channels() && ((1 << CV_MAT_TYPE(flags)) & fixedDepthMask) != 0));

If I remove the cv::Rect from my code, simplifying it to: 

smallImage.copyTo(largeImage, mask);

it works, albeit it doesn't copy to the correct location. How do I solve this?

2
c++opencvmask

2 Answers

2
votes

The following code works without any error.

    Mat large_img = imread("C:\\Koala.jpg");
    Mat small_img;
    resize(large_img,small_img,Size(100,100),1);
    small_img.copyTo(large_img (Rect(100,100,100,100)));
    imshow("Rsult",large_img);
    waitKey(0);

The small image is re-sized version of large image and it is copied in b/w (100,100) location to (200,200) in the large image. You can adopt these lines according to your requirement.

0
votes

To paste a image scaledImage to resultMat:

 scaledImage.copyTo(resultMat);

But i don't think you can select a roi in Java to copy at a particular region.