Adaptive thresholding

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Description

Thresholds an image using a moving rectangular window.

Usage

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thresh(x, w=5, h=5, offset=0.01)

Arguments

x

An Image object or an array.

w, h

Width and height of the moving rectangular window.

offset

Thresholding offset from the averaged value.

Details

This function returns the binary image resulting from the comparison between an image and its filtered version with a rectangular window. It is equivalent of doing {f = matrix(1, nc=2*w+1, nr=2*h+1) ; f=f/sum(f) ; x>(filter2(x, f)+offset)} but slightly faster. The function filter2 provides hence more flexibility than thresh.

Value

An Image object or an array, containing the transformed version of x.

Author(s)

Oleg Sklyar, osklyar@ebi.ac.uk, 2005-2007

See Also

filter2

Examples

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  x = readImage(system.file('images', 'nuclei.tif', package='EBImage'))
  display(x)
  y = thresh(x, 10, 10, 0.05)
  display(y)