CODEWITHSUNDEEP
javaopencvmat
arjuns
arjuns

Reputation: 382

convertTo() method for Mat is not working properly?

When I run the following code:

        Mat i = Imgcodecs.imread(inFile);
        Mat image = new Mat(i.rows(), i.cols(), CvType.CV_8U);
        i.convertTo(image, CvType.CV_8U, 1.0/255);
        System.out.println(image.type() + ", " + CvType.CV_8U);

        Mat t = Imgcodecs.imread(templateFile);
        Imgproc.Canny(t, t, 50, 200);
        Mat template = new Mat(t.rows(), t.cols(), CvType.CV_8U);
        t.convertTo(template, CvType.CV_8U, 1.0/255);
        System.out.println(template.type() + ", " + CvType.CV_8U);

        System.out.println((image.depth() == CvType.CV_8U) + ", " + (image.type() == template.type()) + ", " + image.dims());

        int result_cols = image.cols() - template.cols() + 1;
        int result_rows = image.rows() - template.rows() + 1;
        Mat result = new Mat(result_rows, result_cols, CvType.CV_32FC1);

        Imgproc.matchTemplate(image, template, result, match_method);

I get the following output and runtime error on the line with matchTemplate():

16, 0
0, 0
true, false, 2
OpenCV Error: Assertion failed ((depth == CV_8U || depth == CV_32F) && type == _templ.type() && _img.dims() <= 2) in matchTemplate, file /Users/rajs/Vision/opencv/modules/imgproc/src/templmatch.cpp, line 1062
Exception in thread "AWT-EventQueue-0" CvException [org.opencv.core.CvException: cv::Exception: /Users/rajs/Vision/opencv/modules/imgproc/src/templmatch.cpp:1062: error: (-215) (depth == CV_8U || depth == CV_32F) && type == _templ.type() && _img.dims() <= 2 in function matchTemplate

As can be seen from the output, the reason why the boolean statement is failing is due to the type of the template and that of the image not matching. But, why don't they match after I call the convertTo() method?

Upvotes: 0

Views: 771

Answers (1)

arjuns
arjuns

Reputation: 382

Nevermind, I figured it out. Apparently you have to call:

Imgproc.cvtColor(t, t, Imgproc.COLOR_BGR2GRAY);

before you convert.

Upvotes: 1

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