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Topic: Hog descriptor
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amira ali

Posts: 160
Registered: 5/15/11
Hog descriptor
Posted: Apr 26, 2013 7:42 AM
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can anyone help me please,i use hog descriptor to descripe detected interest poins ,

hog descriptor steps:
1- take image and compute gradient of graysacle input image then descripe it.

how can i update it to compute HOF (histogram of optical flow)??as the ouput of optical flow is gradient magnitudes from optical flow fields , so really i compute gradient for opticl flow
so i don't need to compute gradient again in embeded code of HOG

keypoints = cv.FAST(im,'Threshold',30,'NonMaxSupression',1);
hog = cv.HOGDescriptor('WinSize',[16,16],'BlockSize',[8,8],'BlockStride',[4,4],'CellSize',[4,4] );
descriptors = hog.compute(im, 'Locations', {keypoints.pt});first shape decriptor


prevIm = cv.cvtColor(imread('test\img1.jpeg'),'RGB2GRAY');
nextIm = cv.cvtColor(imread('test\img2.jpeg'),'RGB2GRAY');
flow = cv.calcOpticalFlowFarneback(prevIm, nextIm);
Fx=flow(:,:,1);
Fy=flow(:,:,2);
****magnitudeImage = (Fx.^2 + Fy.^2 ).^0.5;
descriptors2 = hog.compute(im2uint8(magnitudeImage) , 'Locations', {keypoints.pt});???????????/is this true****second motion descriptor



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