Extract Larger Objects from an Image

One application of TopHatTransform is to highlight objects of different sizes in an image.

    
The source image contains washers of various sizes:
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Click for copyable input
Smaller values will extract the smaller washers:
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Click for copyable input
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Use Manipulate to interactively set the value. Larger values for TopHatTransform will select progressively larger washers in the image: