cv_utils.py 文件源码

def get_largest(im, n):
    # Find contours of the shape
    major = cv2.__version__.split('.')[0]
    if major == '3':
        _, contours, _ = cv2.findContours(im.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    else:
        contours, _ = cv2.findContours(im.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    # Cycle through contours and add area to array
    areas = []
    for c in contours:
        areas.append(cv2.contourArea(c))

    # Sort array of areas by size
    sorted_areas = sorted(zip(areas, contours), key=lambda x: x[0], reverse=True)

    if sorted_areas and len(sorted_areas) >= n:
        # Find nth largest using data[n-1][1]
        return sorted_areas[n - 1][1]
    else:
        return None