feature.py 文件源码

def calculate_feature(bin_data):
    """
    calculate the feature data of an image

    parameter :
        'bin_data' is the binary stream format of an image
    return value :
        a tuple of ( keypoints, descriptors, (height,width) )
        keypoints is like [ pt1, pt2, pt3, ... ]
        descriptors is a numpy array
    """
    buff=numpy.frombuffer(bin_data,numpy.uint8)
    img_obj=cv2.imdecode(buff,cv2.CV_LOAD_IMAGE_GRAYSCALE)
    surf=cv2.FeatureDetector_create("SURF")
    surf.setInt("hessianThreshold",400)
    surf_extractor=cv2.DescriptorExtractor_create("SURF")
    keypoints=surf.detect(img_obj,None)
    keypoints,descriptors=surf_extractor.compute(img_obj,keypoints)
    res_keypoints=[]
    for point in keypoints:
        res_keypoints.append(point.pt)
    del buff
    del surf
    del surf_extractor
    del keypoints
    return res_keypoints,numpy.array(descriptors),img_obj.shape