def removeDarkAreas img wrk np copy img areas cv2 findContours wrk cv2

def removeDarkAreas(img):
    wrk = np.copy(img)
    areas, _ = cv2.findContours(wrk, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
    rects = [ cv2.boundingRect(c) for c in areas ]
    avgs=[]
    for r in rects:
        region = img[r[1]:r[1]+r[3],r[0]:r[0]+r[2]]
        avgs.append(np.average(region[region > 0]))
    goodRects = [ avgs[i] for i in range(len(rects)) if rects[i][2] <= 15 and rects[i][3] <= 15 and rects[i][3] > 6]
    avg = np.average(goodRects)
    stddev = np.std(goodRects)
    print avg, stddev
    for i in range(len(rects)):
        r = rects[i]
        if r[2] > 30 or r[3] > 30 or r[3] == 1 or r[2]*r[3] < 8 or abs(avgs[i] - avg) > stddev * 5:           
            img[r[1]:r[1]+r[3],r[0]:r[0]+r[2]] = 0