<Learning OpenCV>练习中Top Hat的处理问题

[e10101]

在<Learning OpenCV>的第五章"Image Processing"中的随章练习的第九题目:

9.Load an image of a scene and convert it to grayscale.
a.Run the morphological Top Hat operation on your image and display the results.
b.Convert the resulting image into an 8-bit mask.
c.Copy a grayscale value into the Top Hat pieces and display the results.

其中的b,c不知道题目要求是什么意思,不知道应该怎样实施.还请给为高手为小弟解答.谢谢!