Template Matching in Android using openCV

Question

I'm trying to match an image with the camera input in Android using template matching. When i try this with static 2 images like in here: OpenCV Template Matching example in Android, everything works just fine. But when I try to use the captured images from the camera, I do not get the correct result. Following is the code that I have written:

  String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath();


                Mat img = Highgui.imread(baseDir + "/mediaAppPhotos/img2.png");
                Mat templ = Highgui.imread(baseDir+ "/mediaAppPhotos/chars.png");


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

                // / Do the Matching and Normalize
                Imgproc.matchTemplate(img, templ, result, Imgproc.TM_CCOEFF);
                Core.normalize(result, result, 0, 1, Core.NORM_MINMAX, -1,
                        new Mat());

                // / Localizing the best match with minMaxLoc
                MinMaxLocResult mmr = Core.minMaxLoc(result);

                Point matchLoc;
                if (Imgproc.TM_CCOEFF == Imgproc.TM_SQDIFF
                        || Imgproc.TM_CCOEFF == Imgproc.TM_SQDIFF_NORMED) {
                    matchLoc = mmr.minLoc;
                } else {
                    matchLoc = mmr.maxLoc;
                }

                // / Show me what you got
                Core.rectangle(
                        img,
                        matchLoc,
                        new Point(matchLoc.x + templ.cols(), matchLoc.y
                                + templ.rows()), new Scalar(0, 255, 0));

                // Save the visualized detection.
                System.out.println("Writing " + baseDir+ "/mediaAppPhotos/result.png");
                Highgui.imwrite(baseDir + "/mediaAppPhotos/result.png", img);

I want to this template matching to work when the image is captured from the camera as well. Any help is greatly appreciated!

Instantaneous

It would help if you could describe what is wrong with the camera image result. – Prologue

If I cut off a part of the source image and use it as the template image to do the matching, then it works fine. But if I use the same template to match the same source image, captured with a slight height or position change, then it does not work! – Instantaneous

Make sure your template is smaller than the image you are matching. – Writer

Good point, may be a memory issue case. Anything useful in the logs ? – Gershon

@Writer : can you please provide some suggestions on this question ? – Polymeric

Answer 1

maybe is like this:

https://play.google.com/store/apps/details?id=in.mustafaak.imagematcher&hl=es_419

code available in github

Investigation