object detection android opencv

Question

After taking a picture with an android phone I want to identify an object in the picture by clicking into it for example. Possible objects in most cases:
1. Ruler
2.

Answer 1

I don't know if you tried this, but usually, you can achieve better results by processing the image first.

1) Apply GuassianBlur to remove the noise

2) Apply AdaptiveThreshold -> to convert the image to black and white

3) Apply Dilate operation, to fill the cracks

By using different settings for the AdaptiveThreshold and the Dilate operation, you might be able to get closed contours...

An example I used is like this:

// 1) Apply gaussian blur to remove noise
Imgproc.GaussianBlur(mGraySubmat, mIntermediateMat, new Size(11,11), 0);

// 2) AdaptiveThreshold -> classify as either black or white
Imgproc.adaptiveThreshold(mIntermediateMat, mIntermediateMat, 255, Imgproc.ADAPTIVE_THRESH_MEAN_C, Imgproc.THRESH_BINARY, 5, 2);

// 3) Invert the image -> so most of the image is black
Core.bitwise_not(mIntermediateMat, mIntermediateMat);

// 4) Dilate -> fill the image using the MORPH_DILATE
Mat kernel = Imgproc.getStructuringElement(Imgproc.MORPH_DILATE, new Size(3,3), new Point(1,1));
Imgproc.dilate(mIntermediateMat, mIntermediateMat, kernel);