crackrec(crackrec)R Documentation

crackrec

Description

Finds cracks (darker areas) in an image.

Usage

crackrec(x, threshold=NULL, alpha=1, beta=1, size=0)

Arguments

x matrix representation of an image, which can be obtained by the function rbmp.
threshold threshold value. The default value is threshold=min(140,mean(x)*4/5).
alpha parameter for weight function with values in [0, 1]. This parameter is optional. The default value is alpha=1.
beta parameter for weight function with values in [0, 1]. This parameter is optional. The default value is beta=1.
size only crackclusters greater than size=n will be considered. The default value is size=0, which means that every crackcluster is considered.

Details

Here each pixel of the image with grey scale value less than the threshold value are treated as vertices of a graph. If vertice u is a direct neighbor of vertice v they are connected by an undirected edge with weight dist*(1 + alpha*(greyValue_u+greyValue_v) + beta*abs(greyValue_u-greyValue_v)). Where dist is equal to 1 if u and v coincide in one component and sqrt(2) else, alpha and beta as described above and greyValue_u means the grey scale value of u. Respectively for vertice v.

Value

a list containing:

cracks matrix containing crack length, crack size, start and endpoint of cracks
crackpaths list of crack paths
crackclusters list of connected components (maximal connected subgraphs)

Author(s)

Arne Mueller, Alexander Stepper stepper@mathematik.uni-kassel.de

See Also

rbmp, threshold.msi, shadow.remove, medianfilter, crackplot

Examples

## Not run: 
x<-rbmp("image.bmp")
crackrec(x, threshold=123, alpha=0, beta=0)
## End(Not run)

[Package crackrec version 2.1.5 Index]