Example OpenCV feature extracteor

extract_features.py

# Feature extractor
def extract_features(image_path, vector_size=32):
    image = imread(image_path, mode="RGB")
    try:
        # Using KAZE, cause SIFT, ORB and other was moved to additional module
        # which is adding addtional pain during install
        alg = cv2.KAZE_create()
        # Dinding image keypoints
        kps = alg.detect(image)
        # Getting first 32 of them. 
        # Number of keypoints is varies depend on image size and color pallet
        # Sorting them based on keypoint response value(bigger is better)
        kps = sorted(kps, key=lambda x: -x.response)[:vector_size]
        # computing descriptors vector
        kps, dsc = alg.compute(image, kps)
        # Flatten all of them in one big vector - our feature vector
        dsc = dsc.flatten()
        # Making descriptor of same size
        # Descriptor vector size is 64
        needed_size = (vector_size * 64)
        if dsc.size < needed_size:
            # if we have less the 32 descriptors then just adding zeros at the
            # end of our feature vector
            dsc = np.concatenate([dsc, np.zeros(needed_size - dsc.size)])
    except cv2.error as e:
        print 'Error: ', e
        return None

    return dsc

Hi there am getting this error while executing on multiple jpeg files

AttributeError: 'NoneType' object has no attribute 'flatten'

@AnTri

Hi there am getting this error while executing on multiple jpeg files

AttributeError: 'NoneType' object has no attribute 'flatten'

Got this too, I think because of using too small images. I fixed this by increasing the threshold in KAZE_create:

alg = cv2.KAZE_create(threshold=0.0001)

Try different thresholds until you have no failing images.