bwperim

J = bwperim(I::Union{GMTimage{<:UInt8, 2}, GMTimage{<:Bool, 2}}; hsize=3, vsize=3, sel=nothing)::GMTimage

Find perimeter of objects in binary image I.

A pixel is part of the perimeter if it is nonzero and it is connected to at least one zero-valued pixel. To detect the image’s perimeter, the structuring element should a box of size 3 x 3 (or, better, use the defaults), but a different sizes can be provided. This operation, consisting on subtracting an erosion of I from I, is alsoknown as a morphological internal gradient.

Args

  • I::Union{GMTimage{<:UInt8, 2}, GMTimage{<:Bool, 2}}: Input image.

Kwargs

  • hsize::Int=3: Horizontal size of the ‘box’ structuring element.

  • vsize::Int=3: Vertical size of the ‘box’ structuring element.

  • sel=nothing: Structuring element (See strel function). An alternative to hsize and vsize options. If equal to nothing, a structuring box of size hsize x vsize is used.

Returns

A new GMTimage of the same type as I with the perimeter.

Example

The result will look like the outline of the object.

using GMT

I = gmtread(TESTSDIR * "assets/circles.png");
J = bwperim(I);
grdimage(I, figsize=6)
grdimage!(J, figsize=6, xshift=6, show=true)

See Also

imdilate, imerode, strel