Iterative Fuzzy Clustering Regions of Interest in Skin Lesions

By R. Cucchiara, C. Grana, M. Piccardi

Presented by Mohammed Jirari October 23rd, 2002

Image Processing Lab

Introduction Definition of Skin Melanoma Systems used for Melanoma

diagnosis Recent research

Method used in paper Preprocessing Karhunen-Loeve transform Fuzzy c-means clustering Topological tree

Preprocessing Convolve the image with a

Gaussian kernel with standard deviation of one pixel.

Transform images from original RGB into CIE L*a*b* color coordinates.

Karhunen-Loeve transform Projection of the vectors to be

reduced on the eigenvectors of their covariance matrix using the following:

M

k

Txx

Tkkx

M

kkx

mmxxM

C

xM

m

1

1

1

1

Karhunen-Loeve transform (cont.) The Karhunen-Loeve transform of

vector x is defined by:

xmxAy

Fuzzy c-means clustering Use the following 2 recurrent

equations:

M

k

mik

M

kk

mik

i

mc

ijj

jk

ikik

U

xUv

vx

vxU

1

1

1

1

1

12

2

1

Topological tree Bright clusterHealthy skin Dark cluster Lesion

Topological tree (cont.) Def1:Skin region of Interest(Skin ROI)

a set of pixels of the skin image exhibiting 3 properties: uniform color, connected pixels and significant area.

Def2:Topological Tree(TT)a tree whose nodes are skin ROIs and the arcs topological inclusion relationships between skin ROIs

Pseudo-code of the algorithmAnalyzeRegion (region R, node N){if(not StopCondition (R)){

[C1,C2]=FCM(R);

[Cint,Cext]=VerifyInclusion([C1,C2]);

if(exists([Cint,Cext])){

Cres=R-Cint-Cext;

Nnew=AddNodeToTree(Cext,N);

for each C in ConnectedComponents(Cint)

AnalyzeRegion(C+Cres,Nnew);}else {

Analyzeregion(R-C1,N);

AnalyzeRegion(R-C2,N);}}

else AddNodeToTree(R,N);}