bothat

The (black) tophat operator, also known as bottom hat, is defined as closing(img) - img. Intuitively, this filter can be used to extract small black elements and details from an image.

using ImageMorphology
using TestImages
using ImageBase
using ImageShow

img = restrict(testimage_dip3e("fig1038")) # fingerprint

out1 = bothat(img) # default: all spatial dimensions, r=1, a box-shape SE
out2 = bothat(img; dims=(2,)) # only apply to the second dimension
out3 = bothat(img; r=5) # half-size r=5
out4 = bothat(img, strel_diamond((5, 5))) # generic SE -- this version doesn't accept `r` and `dims`

mosaic(img, out1, out2, out3, out4; nrow=1)

See also

To extract white small details, use the white tophat:

tophat(img) == bothat(complement.(img))

false

For a comprehensive and more accurate documentation, please check the bothat reference page.

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