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2014-11-30 00:05:17 -0500 asked a question Has OpenCV built-in functions to calculate circularity, compactness etc for contours/blobs?

Compactness can be defined for example as the perimeter squared, divided by 4piarea, so that a circle has a compactness of 1.

Before writing my own function, Is there a similar function in the OpenCV Library ?

Thanks.

Ps : SimpleBlobDetector does not help me as I want to calculate circularity for existing prior extracted contours.

2014-11-27 06:50:39 -0500 commented answer Simple matrix operation not working : is it normal ?

Sorry I found the error. It was very stupid. My image is binary so a multiplication by 255 doesn't change anything (blacks pixels are 0's so remain black). I don't have an issue anymore.

2014-11-27 06:48:00 -0500 commented answer Simple matrix operation not working : is it normal ?

the image come from image = imread(argv[1], CV_LOAD_IMAGE_GRAYSCALE); So it should be CV_8UC1. I don't want the image to be white, it was just for testing the multiplication. What do you mean by passing by value instead of reference ? Normally it should be automatically be passed by reference, no ?

2014-11-23 04:42:51 -0500 asked a question Simple matrix operation not working : is it normal ?

If I write for example image=255*image, the value of image is not updated (I should get a full white image). Is this normal ? Do I have to go through inner loops to multiply each element ?

2014-11-15 05:55:11 -0500 asked a question What does that line mean, in the documentation about native android developpement ?

From : http://docs.opencv.org/doc/tutorials/introduction/android_binary_package/dev_with_OCV_on_Android.html#native-c

You can use an environment variable to specify the location of OpenCV package or just hardcode absolute or relative path in the jni/Android.mk of your projects.

What package are we talking about ? Is it the same thing as include ../../sdk/native/jni/OpenCV.mk ?

2014-11-15 05:53:52 -0500 asked a question What does that line mean in Native Android OpenCV documentation ?

From : http://docs.opencv.org/doc/tutorials/introduction/android_binary_package/dev_with_OCV_on_Android.html#native-c

You can use an environment variable to specify the location of OpenCV package or just hardcode absolute or relative path in the jni/Android.mk of your projects.

What package are we talking about ? Is it the same thing as include ../../sdk/native/jni/OpenCV.mk ?

2014-11-10 14:11:53 -0500 asked a question Is there a function to convert to IHLS space ?

in OpenCV or even written by someone else. Thanks

2014-11-10 14:09:16 -0500 commented question What exactly is a Blob in OpenCV ?

Unfortunately that doesn't answer my question, I need a correct definition of a blob, like a definition of a line or a circle.

2014-11-09 17:19:16 -0500 asked a question What exactly is a Blob in OpenCV ?

When I run the SimpleBlobDetector, it fails to detect hollow circles (like a donut) but it detects any plain object. So I am confused, what's the definition of a blob ?

2014-11-09 10:26:13 -0500 asked a question Is the OpenCV Manager (Android) useful if we want to developp natively ?
2014-11-08 00:17:21 -0500 commented question How do I threshold between two values a and b ?

Given the Matrix M, I threshold it (binary) with threshold value a, the ouput is A. Then I threshold M again (binry inverted) with value b, the output is B. Then if I multiply A and B component wise (Hadamard product) I should get what I want.

But I found the "inrange" function which does that automatically.

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2014-11-07 19:56:32 -0500 asked a question How do I threshold between two values a and b ?

Sure I can create two thresholded Mat, one for each bound a and b, and multiply them component-wise, but how do I do that ?

2014-10-21 18:05:28 -0500 asked a question Is it possible to have multithreading on Android OpenCV ?

Or will Android necessary compile the C++ functions as single threads ?