OpenCV / SURF How to generate a image hash / fingerprint / signature out of the descriptors?

The feature data you mention (position, laplacian, size, orientation, hessian) is insufficient for your purpose (these are actually the less relevant parts of the descriptor if you want to do matching). The data you want to look at are the “descriptors” (the 4th argument): void cvExtractSURF(const CvArr* image, const CvArr* mask, CvSeq** keypoints, CvSeq** descriptors, … Read more

OpenCV: process every frame

According to the code below, all callbacks would have to follow this definition: IplImage* custom_callback(IplImage* frame); This signature means the callback is going to be executed on each frame retrieved by the system. On my example, make_it_gray() allocates a new image to save the result of the grayscale conversion and returns it. This means you … Read more

java.lang.UnsatisfiedLinkError: Native Library XXX.so already loaded in another classloader

The problem is with how OpenCV handles the initialization of the native library. Usually a class that uses a native library will have a static initializer that loads the library. This way the class and the native library will always be loaded in the same class loader. With OpenCV the application code loads the native … Read more