Python PIL ImageStat.Stat上的py2exe引发异常：参数2必须是ImagingCore，而不是ImagingCore

我试图使用py2exe从python程序中创建一个.exe，但当我运行该.exe时，会得到一个带有

Exception in thread Thread-1:
Traceback (most recent call last):
  File "threading.pyc", line 532, in __bootstrap_inner
  File "threading.pyc", line 484, in run
  File "webcam.py", line 66, in loop
  File "ImageStat.pyc", line 50, in __init__
  File "PIL\Image.pyc", line 990, in histogram
TypeError: argument 2 must be ImagingCore, not ImagingCore

下面是一些代码：

#webcam.py
          cam = VideoCapture.Device();
          def getImage():
            return cam.getImage();
    ...
        camshot = grayscale(getImage());
        lightCoords = [];
        level = camshot.getextrema()[1]-leniency;
        for p in camshot.getdata():
          if p>=level:
            lightCoords.append(255);
          else:
            lightCoords.append(0);
        maskIm = new("L",res);
        maskIm.putdata(lightCoords);
    ...

    64      colorcamshot = getImage();
    65      camshot = grayscale(colorcamshot);
    66      brightness = ImageStat.Stat(camshot,maskIm).sum[0]/divVal;

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在启动任何工作线程之前，请尝试在主线程中导入PIL。看起来同一个类已经被导入了两次，因此类型比较显得很奇怪