Image classification using SVM

asked 2016-05-17 09:03:48 -0600

sara1691362
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i'm using opencv svm and i want to know if it is possible to know which image is closer to our input image instead of the class which belongs our image.

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this might not be possible.

an SVM does not keep the train data around, all it keeps are the support vectors.

berak ( 2016-05-17 10:42:01 -0600 )edit

thank you for your answer. can you please tell me what method can i use to solve this problem?

sara1691362 ( 2016-05-17 12:50:26 -0600 )edit

it's not an answer (so far)

an SVM does classification , but your question hints, that you want something slightly different, like finding the 'closest neighbour' ? a simple 'nearest neighbour search' (e.g. comparing all of your train samples to the test one using norm(a,b), and keeping the one with lowest score) would do that, also there's flann::Index

berak ( 2016-05-17 13:01:13 -0600 )edit

is there a possible way to get the closest neighbour + the class which belongs the image (using the nearest neighbour ) ?

sara1691362 ( 2016-05-17 16:33:09 -0600 )edit

sidenote: do you really need the closest image ? or would any image from the predicted class do?

berak ( 2016-05-18 02:14:37 -0600 )edit

i need the closest image + which class it belongs

sara1691362 ( 2016-05-18 04:56:16 -0600 )edit

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void nearest(const cv::Mat &testData, const vector<cv::Mat> &trainData, int &best, double &mind) { mind=DBL_MAX; best = -1; for (size_t r=0; r<trainData.size(); r++) { double d = norm(testData, trainData[r]); if (d < mind) { mind = d; best = r; } } } vector<Mat> trainData = ... vector<int> trainLabels = ... Mat testData = ... int best; double dist; nearest(testData, trainData, best, dist); int predicted = trainLabels[best]; Mat closest = trainData[best];

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I am currently working on a project where I have to extract the facial expression from a video. I've extracted the landmarks, now i want to classify the emotions + get the closest image's landmarks. So is there a possibility to do the classification based on the facial landmarks?

sara1691362 ( 2016-05-18 05:53:07 -0600 )edit

sure, just put your landmarks into a Mat

berak ( 2016-05-18 06:43:47 -0600 )edit

can you please tell me how can i do that?

sara1691362 ( 2016-05-18 06:44:39 -0600 )edit

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Image classification using SVM

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